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The African species of the water beetle genus Ochthebius Leach (1815), subgenus Aulacochthebius Kuwert (1887) are revised. Nine new species are described, based on the examination and databasing of 5,911 specimens from 101 localities. Male genitalia are illustrated, and high resolution habitus images of the holotypes and specimens of previously described species are provided. Distribution maps are provided for the sixteen species now known from Africa and Madagascar, including specimens from Angola, Benin, Botswana, Burkina Faso, Chad, Ethiopia, Gambia, Ghana, Kenya, Lesotho, Mali, Morocco, Namibia, Nigeria, Senegal, South Africa, Uganda, Zimbabwe, and Madagascar. New species of O. (Aulacochthebius) are: O. (A.) copiosus n. sp.; O. (A.) flagellissimus n. sp.; O. (A.) latissimus n. sp.; O. (A.) mpumalangicus n. sp.; O. (A.) multilineatus n. sp.; O. (A.) nigeriensis n. sp.; O. (A.) persetosus n. sp.; O. (A.) scutatus n. sp.; and O. (A.) solitarius n. sp. The morphology of O. (A.) exaratus Mulsant, including the aedeagal morphology, is presented, and consequently O. (A.) strangulatus Régimbart is removed from synonymy with O. (A.) exaratus Mulsant.

Hydraena (Hydraenopsis) turneri sp. nov. (Figs. 1C–D, 2B–C) Type locality. São Tomé, trail from Ponta Figo, seepage, 0˚17′10′′N 6˚34′8.6′′E, 629 m. Type material. Holotype (male): “ SÃO TOMÉ, Ponta Figo trail// ref: ST27, leg. C.R.Turner // 00°17′10.3”N 6°34′8.6”E, 629 m // 28 October 2016, seep on cutting by track// steep mountain slope, primary forest” (genitalia extracted and mounted on same card) and red holotype label (NHML). Paratypes (58): São Tomé: 35♁ 23♀, same data as holotype. All with red paratype labels (AMG, CDTB, CCRT, ISAM, NHML, NHMW). Description. Size: Holotype: BL 1.55 mm; EL 0.95 mm; EW 0.65 mm. Paratypes: Males BL 1.45–1.55 mm; EL 0.85–0.90 mm; EW 0.60–0.65 mm. Females BL 1.60–1.65 mm; EL 0.95–1.00 mm; EW 0.65–0.70 mm. Colour: Dorsum dark brown to black (Fig. 1C); anterior angles of pronotum and elytral margins paler; legs brown, tarsi slightly paler; maxillary palpi light brown; antennal stem segments brown, club somewhat darker; Venter dark brown to black; underside of head, pronotal hypomeron and elytral epipleurs paler brown. Head: Broadly triangular, broadest at hind margin of eyes; narrowing abruptly in front of clypeus; narrowest at apex of labrum. Compound eyes moderate, occupying approximately 1/2 of side margin of head excluding labrum, with 12 ommatidea in longest series. Labrum transverse, deeply emarginate anteromedially. Anterior and lateral margins upturned, with short, flat setae. Upper surface of labrum shining, with fine microreticulation and scattered punctures bearing short, recumbent setae. Clypeus shining with moderate, medium punctures bearing short, decumbent setae; with weakly arcuate anterior margin, anterolateral angles obtuse. Frontoclypeal suture distinct, broadly arcuate. Frons much wider than clypeus, with front angles rounded and slightly obtuse; surface shining, with moderate, large, shallow punctures, bearing fine recumbent to decumbent setae; punctures in centre spaced 0.1–4 puncture diameters apart. Maxilary palpi with segment 3 and 4 somewhat expanded. Pronotum: Transverse, weakly arched, slightly cordiform, broadest at middle. Sides dentate, with smaller, curved setae; slightly narrowing from widest point to front angles; abruptly narrowing and weakly arcuate to hind angles. Hind angles slightly acuminate and obtuse; front angles broadly rounded, obtuse. Front margin broadly emarginate in middle half, then sinuous to front angles. Hind margin almost straight, very weakly bisinuate around centre. Disc shining, devoid of microreticulation; moderate, large, shallow punctures, as on head, bearing fine recumbent to decumbent setae; punctures in centre spaced 0.5–3 puncture diameters apart. Anterolateral pronotal foveae shallow, open laterally; posterolateral pronotal foveae very shallow, slightly elongate, open posteriorly. Elytra: Arched, moderately elongate, widest close to middle. Sides weakly rounded to shallowly emarginated apex. Elytral margin explanate, from just behind shoulder to close to apex; minutely serrate. Elytra shining, with 15 non-striate rows of medium, shallow punctures, bearing fine recumbent setae, most not reaching anterior margin of next puncture in series; punctures slightly larger than on pronotum. Elytral disc flat, gradually declining to apex over posterior half. Wings: Full. Venter: Mentum slightly elongate, sharply acuminated apicomedially; anterior and lateral margins with dense, stout, erect, pointed setae; lateral angles rounded; surface shining, with sparse, fine punctures bearing short peglike setae in centre; setae longer and recumbent to decumbent close to posterior margin. Submentum shining, with transverse ridges and shallow, fine punctures bearing fine recumbent to decumbent setae. Gena shining; anterior rides weak and arcuate. Prosternal intercoxal process narrow, shining, carinate; weak triangular posterior projection over mesoventrite. Pronotal hypomera broad, weakly shining, without visible reticulation. Elytral epipleura broad, shining; continued to approx. 1/6 from apex. Mesoventrite shining, rugosely punctate, with sparse, long setose vestiture; plaques strongly developed, median, admedian and adlateral; mesoventral intercoxal process with margins slightly concave around centre, shining and rugose, lateral margins slightly raised. Metaventrite shining, shallowly, rugosely punctured with long setose vestiture and elongate posteromedian depression, opening posteriorly. Metaventral plaques narrow, linear, shining areas adjacent to posteromedian depression with sparse vestiture. Abdominal intercoxal sclerite width at arcuate posterior margin approx. 2x that of apex of mesoventral intercoxal process. Abdominal ventrites 1–4 shining, with long setose vestiture. Ventrite 5 shining, devoid of vestiture, with irregular, transverse setal row anteriorly and posteriorly; apical margin weakly arcuate. Ventrite 6 shining, with weak transverse microreticulation and irregular, transverse setal row posteriorly. Ventrite 7 with weak transverse microreticulation. Reflexed portion of tergite 9 with transverse microreticulation and short internal apodemes. Aedeagus: Elongate (Fig 1D); main piece rather straight, with dorsally reflexed apex in lateral view; gonoporebearing flagellum attaching below well-developed dorsal hood, with crenulated margin. Parameres very small, stout, attached approx. 1/3 from apex on main piece. Females: Largely as males. Differential diagnosis. Amongst known Afrotropical Hydraena the new species is best distinguished by the form of the aedeagus, with small, distally positioned parameres, and a short, curved gonopore-bearing flagellum with a dorsal hood. It differs from H. soatometerrestris sp. nov. on a number of external and aedeagal characters, particularly: darker dorsal colouration; pronotum less constricted towards front angles; elytra narrower, somewhat more parallel-sided in middle, with narrower explanate margin; metaventrite sculpture less marked and less obviously rugose, posteromedian metaventral depression more elongate, metaventral plaques narrower and more elongate; ventral vestiture shorter and denser; aedeagus smaller, with more strongly pronounced angle on right-hand side in ventral view and more well-developed hood over base of gonopore-bearing flagellum (compare Figs 1B & D). Etymology. Named for my long-time friend Clive R. Turner, who collected all known material of this species, and a significant proportion of the type series of H. saotometerrestris sp. nov. Distribution and ecology. Known only from the type locality, a seepage over rock and clay in primary forest beside a trail. Specimens were hand-picked from the surface of wet substrate, and were entirely submerged, suggesting an aquatic lifestyle. The wet substrate displayed two main forms of algal growth both covered by a thin layer of water, one a grey algal film which did not possess any Hydraena and a brown algal film on which they were all found and were well camouflaged on. Searches of other seeps, still waters & larger, flowing streams and rivers on the island by Clive Turner failed to locate any more Hydraena., Published as part of Bilton, David T., 2023, Two new species of Hydraena Kugelann, 1794 from São Tomé Island-an apparent adaptive radiation (Coleoptera, Hydraenidae), pp. 593-600 in Zootaxa 5254 (4) on pages 595-599, DOI: 10.11646/zootaxa.5254.4.11, http://zenodo.org/record/7732056

Bilton, David T. (2023): Two new species of Hydraena Kugelann, 1794 from São Tomé Island-an apparent adaptive radiation (Coleoptera, Hydraenidae). Zootaxa 5254 (4): 593-600, DOI: 10.11646/zootaxa.5254.4.11, URL: http://dx.doi.org/10.11646/zootaxa.5254.4.11

Hydraena (Hydraenopsis) saotometerrestris sp. nov. (Figs. 1A–B, 2A & C) Type locality. São Tomé, Bom Sucesso, forest close to radio tower, ca. 1320 m. Type material. Holotype (male): “ SÃO TOMÉ // Bom Sucesso // Aerial // 6–7.vi.1999 ” “Winkler// sample” “ A. Polazsek // BMNH (E) 2005-138” (genitalia extracted and mounted on same card) and red holotype label (NHML). Paratypes (14): São Tomé: 3♁ 1♀, same data as holotype; 4♁ 6♀ “ SÃO TOMÉ, Pico de São Tomé// ref: ANHRT2018-216, leg. C.R.Turner // 00°16′11.5″N 6°32′38.8″E, 1936 m // 18 Jan 2018, hand searching wet dead leaves// on forest floor” All with red paratype labels (AMG, CDTB, CCRT, NHML, NHMW). Description. Size: Holotype: BL 1.50 mm; EL 0.95 mm; EW 0.70 mm. Paratypes: Males BL 1.50–1.55 mm; EL 0.95–1.00 mm; EW 0.65–0.70 mm. Females BL 1.65–1.70 mm; EL 1.00– 1.05 mm; EW 0.70–0.75 mm. Colour: Dorsum dark reddish brown (Fig. 1A); margins of pronotum paler than disc; clypeus and labrum paler; legs reddish brown, tarsi paler; maxillary palpi yellowish brown; antennal stem segments pale yellowish brown, club somewhat darker; Venter reddish brown; pronotal hypomeron, elytral epipleurs and abdominal ventrites paler; cardo, stipes and palpifer yellow. Head: Broadly triangular, broadest at hind margin of eyes; narrowing abruptly in front of clypeus; narrowest at apex of labrum. Compound eyes moderate, occupying approximately 1/2 of side margin of head excluding labrum, with 10 ommatidea in longest series. Labrum transverse, deeply emarginate anteromedially. Anterior and lateral margins broadly upturned, with short, curved setae. Upper surface of labrum shining, with fine microreticulation and scattered punctures bearing short, recumbent setae. Clypeus shining with sparse, fine punctures bearing short, decumbent setae; with weakly arcuate anterior margin, anterolateral angles obtuse. Frontoclypeal suture distinct, broadly arcuate. Frons much wider than clypeus, with front angles sharp and slightly obtuse; surface shining, with moderate, large, shallow punctures, bearing fine recumbent to decumbent setae; punctures in centre spaced 0.2–3 puncture diameters apart. Maxilary palpi with segment 3 and 4 somewhat expanded. Pronotum: Transverse, strongly arched, slightly cordiform, broadest just behind middle. Sides dentate, with smaller, curved setae; broadly rounded at broadest point, then almost straight to hind angles and rounded to front angles. Hind angles rounded, square; front angles broadly rounded, slightly obtuse. Front margin broadly emarginate in middle half, then sinuous to front angles. Hind margin weakly bisinuate around centre. Disc shining, devoid of microreticulation; moderate, large, shallow punctures, as on head, bearing fine recumbent to decumbent setae; punctures in centre spaced 0.5–3 puncture diameters apart. Anterolateral pronotal foveae very shallow, elongate, open laterally; posterolateral pronotal foveae very shallow, slightly elongate, open posteriorly. Elytra: Broad, arched, moderately elongate, widest close to middle. Sides weakly rounded to shallowly emarginated apex. Elytral margin broadly explanate, from just behind shoulder to close to apex; minutely serrate. Elytra shining, with 15 non-striate rows of medium, shallow punctures, bearing fine recumbent setae, most not reaching anterior margin of next puncture in series; punctures slightly larger than on pronotum. Elytral disc flat, gradually declining to apex over posterior half. Wings: Full. Venter: Mentum slightly transverse, strongly acuminated apicomedially; anterior and lateral margins with dense, stout, erect to suberect, elongate setae; lateral angles broadly rounded; surface shining, with sparse, fine punctures bearing long, fine, recumbent to decumbent setae. Submentum shining, with shallow, sparse, fine punctures bearing fine recumbent to decumbent setae. Gena shining; anterior rides weak and arcuate. Prosternal intercoxal process narrow, shining, carinate; strong triangular posterior projection over mesoventrite. Pronotal hypomera very broad, weakly shining, without visible reticulation. Elytral epipleura very broad, shining; continued to approx. 1/6 from apex. Mesoventrite shining, rugosely punctate, with sparse, long setose vestiture; plaques strongly developed, median, admedian and adlateral; mesoventral intercoxal process with margins slightly concave around centre, shining and rugose, lateral margins slightly raised. Metaventrite strongly rugosely punctured with very long setose vestiture and elongate, triangular posteromedian depression, opening posteriorly. Metaventral plaques reduced to arcuate, shining areas adjacent to posteromedian depression with sparse vestiture. Abdominal intercoxal sclerite width at arcuate posterior margin approx. 3x that of apex of mesoventral intercoxal process. Abdominal ventrites 1–4 shining, with long setose vestiture. Ventrite 5 shining, vestiture restricted to basal 1/3; irregular row of fine punctures bearing elongate setae close to apical margin; apical margin broadly arcuate. Ventrite 6 somewhat shining, with strong transverse microreticulation, devoid of vestiture. Ventrite 7 with strong transverse microreticulation. Reflexed portion of tergite 9 with transverse microreticulation and short internal apodemes. Aedeagus: Elongate (Fig 1B); main piece rather straight, flattened over apical 1/ 3 in lateral view, with complex apex; base of gonopore-bearing flagellum with short dorsal hood. Parameres very small, stout, attached approx. 1/3 from apex on main piece. Females: Largely as males. Apical abdominal ventrites with more extensive vestiture. Differential diagnosis. Amongst known Afrotropical Hydraena the new species is best distinguished by the form of the aedeagus, with small, distally positioned parameres, and a short, curved gonopore-bearing flagellum with a dorsal hood. For separation from H. turneri sp. nov. see under than species below. Etymology. Named in reference to the geographical location and apparent ecology, in forest leaf litter. Distribution and ecology. Known from two high-altitude forest locations in the centre of the island, at least one of which (Pico de S„o Tomé) is within Parque Natural Ôbo. Likely widespread in suitable habitat in these mountains.At the type locality, material was collected from leaf litter with a Winker sampler. Clive Turner collected most specimens by hand searching leaf litter below tree ferns just below the summit of Pico de S„o Tomé, beetles always being found crawling in water films on wet, well-decayed leaves. Sifting in the same place only produced one specimen., Published as part of Bilton, David T., 2023, Two new species of Hydraena Kugelann, 1794 from São Tomé Island-an apparent adaptive radiation (Coleoptera, Hydraenidae), pp. 593-600 in Zootaxa 5254 (4) on pages 594-595, DOI: 10.11646/zootaxa.5254.4.11, http://zenodo.org/record/7732056

Decarthrocerus jeanneli Orchymont, 1948 (Figs 3–4) Material studied. 1 J 1 ♀, “ MALAWI: Mt. Dedza / Dedza env., 2030 m / S14°21’42.3’’ E34°10’50.0’’ / 28.XI.2018, P.Hlaváč lgt.” (NMPC); 1 J, “ TANZANIA, Mt. Ha- / nang, S. slope, / S4.46111° E35.39741° / 2383m, 17.xii.2012, sift. 23 V. Grebennikov leg.”, “DNA specimen / E.E. IBE-AN536” (CRM). Comments. A species described from Mt Elgon, Kenya (ORCHYMONT 1948, PERKINS 2009) and not so far reported elsewhere. I have seen material apparently referable to this species from Malawi and Tanzania. Males, together with their aedeagi, are shown in Fig. 3, alongside a paratype from Mt Elgon (after PERKINS 2009). Whilst there are small differences between specimens, these are much smaller than those seen between described species of Decarthrocerus (see PERKINS 2009). As there do not appear to be any significant, consistent differences between populations, either aedeagal or external, I consider these conspecific, particularly in the absence of genetic data, despite the large geographical distances between them (Fig. 4). Similar situations have been reported in other East African mountain beetle taxa, including hydraenids (see e.g. BILTON 2021)., Published as part of Bilton, David T., 2023, New species and new records of minute moss beetles from East Africa (Coleoptera: Hydraenidae), pp. 103-110 in Acta Entomologica Musei Nationalis Pragae 63 (1) on page 109, DOI: 10.37520/aemnp.2023.004, http://zenodo.org/record/7887285, {"references":["ORCHYMONT A. D' 1948: Mission Scientifique de l'Omo. Coleoptera XV. Hydraenidae. Memoires du Museum National d'Histoire Naturelle, Nouvelle Serie 27: 29 - 62.","PERKINS P. D. 2009: Revisions of the genera Parhydraena Orchymont, Protozantaena Perkins, Decarthrocerus Orchymont, and Parhydraenopsis nomen novum, aquatic and humicolous beetles from Africa and Madagascar, and comparative morphology of the tribe Parhydraenini (Coleoptera: Hydraenidae). Zootaxa 2038: 1 - 119.","BILTON D. T. 2021: Riberazantaena, a new hydraenid genus from the Eastern Arc Mountains of Tanzania (Coleoptera, Hydraenidae). Zootaxa 4999: 573 - 581."]}

Despite much recent progress, knowledge of Afrotropical Hydraenidae remains limited, particularly in areas experiencing tropical climates, where large numbers of species likely remain undetected. Here, three new species are described from material recently col­lected from two Malawian mountains: Coelometopon dedzae sp. nov. from Mount Dedza and Hydraena (Hydraenopsis) mulanje sp. nov. and Ochthebius (Asiobates) erinaceus sp. nov. from Mount Mulanje. All specimens were sampled by sifting, and Hydraena mulanje sp. nov. and Ochthebius erinaceus sp. nov. appear to be terrestrial, in forest litter. Specimens of Decarthrocerus Orchymont, 1948 from Mount Dedza are apparently referable to D. jeanneli Orchymont, 1948, described from Mount Elgon, Kenya, as is a specimen examined from Mount Hanang in Tanzania. These represent new country records for this species, which appears to be widespread in East African Mountains.

Hydraena (Hydraenopsis) mulanje sp. nov. (Figs 1–2, 4) Type locality. Malawi, Mt. Mulanje, Ruo River Forest, 15°58′17.0″S 35°39′18.3″E, 970 m. Type material. HOLOTYPE: J, labelled:“S MALAWI. Mulanje Mts./ Ruo river Forest / S15°58’17.0’’ E35°39’18.3’’ / 18-25.xi.2018, 970 / sifting P.Hlaváč lgt.” (NMPC) with red holotype label. PARATYPES: 1 J 3 ♀♀, same data as Holotype; 1 ♀, labelled: “ MALAWI: Mt. Mulanje / Ruo river Forest, sifting, 970m / S15°58’17.0’’ E35°39’18.3’’ / 18-25.xi.2018, P.Hlaváč lgt.”, all with red paratype labels (NMPC). Description. Male. Colour. Dorsum (Fig. 1B) predominantly reddish brown; pronotum lighter than elytra except on parts of disc; head darkened posteriorly and almost black inside of compound eyes, legs light reddish brown; maxillary palpi yellowish brown; antennal stem segments pale yellowish brown, club somewhat darker; venter reddish brown to dark brown. Head broadly triangular, broadest at posterior margin of eyes; narrowing abruptly in front of clypeus; narrowest at base of labrum. Compound eyes relatively large, occupying approximately 1/2 of side margin of head excluding labrum. Labrum transverse, deeply emarginate anteromedially, creating two rounded lateral lobes; lobes widest at base, labrum distinctly narrowed behind. Anterior and lateral margins slightly thickened and upturned, with short, curved setae. Upper surface of labrum dull, with fine microreticulation and scattered punctures bearing short, curved setae. Clypeus shining, with very sparse, short, curved setae; with weakly arcuate anterior margin, anterolateral angles obtuse; lateral margins slightly thickened, minutely serrate, with small, curved setae. Frontoclypeal suture indistinct, weakly arcuate. Frons much wider than clypeus, with front angles sharp and slightly obtuse; margins minutely serrate and setose in front of compound eyes; surface shining in centre, with dense, large, shallow punctures, bearing fine recumbent to decumbent setae; punctures in centre spaced 0.1–1 puncture diameter apart; closer towards inner margins of compound eyes, where cuticle has a somewhat rugose appearance. Maxillary palpi with palpomeres 3 and 4 somewhat expanded. Pronotum transverse, cordiform, broadest just behind middle. Sides dentate, with smaller, curved setae; broadly rounded at broadest point, then weakly concave to posterior angles and weakly concave, then broadly rounded to anterior angles. Posterior angles pointed, weakly obtuse; anterior angles right angled. Anterior margin broadly emarginate in middle half, then almost straight to anterior angles. Posterior margin weakly bisinuate around centre and slightly recurved to posterior angles. Disc shining, devoid of microreticulation; with dense, large, shallow punctures bearing fine recumbent to decumbent setae; punctures larger than on head, spaced 0.1–2 puncture diameters apart. Pronotum weakly rugose towards lateral margins, particularly anteriorly. Anterolateral pronotal foveae shallow, transverse, open laterally; posterolateral pronotal foveae shallow, slightly elongate, continued to posterior margin. Elytra broad, moderately elongate, widest close to middle. Sides weakly rounded to shallowly emarginated apex. Elytral margin broadly explanate, from just behind shoulder to close to apex; minutely serrate. Elytra shining, with 15 non-striate rows of large, shallow punctures, bearing long, fine recumbent setae, many lost; punctures larger and deeper than on pronotum. Elytral disc flat, gradually declining to apex over posterior half. Venter. Mentum transverse, produced into broad triangular process apicomedially; anterior margins with dense suberect setae; lateral angles broadly rounded; surface shining, with sparse, fine punctures bearing long, fine recumbent to decumbent setae. Gena shining, without transverse ridges. Prosternal intercoxal process carinate, rugulosely sculptured. Pronotal hypomera broad, somewhat dull, with rugulose reticulation. Elytral epipleura broad, dull, isodiametrically microreticulate; continued almost to apex. Mesoventrite dull, strongly and rugulosely microreticulate, with dense setose vestiture; mesoventral intercoxal process parallel sided, lateral margins raised and shining. Metaventrite rugulosely punctured with dense vestiture and oval posteromedian depression; with short arcuate ridge on each side, extended posteriorly from margin of each mesocoxal cavity. Mesoventral plaques elongate ovals, flat, shining and slightly raised above rest of ventrite. Abdominal intercoxal sclerite width at arcuate posterior margin approx. 2× that of apex of mesoventral intercoxal process. Abdominal ventrites 1–4 slightly shining, with scale-like microreticulation and setose vestiture. Ventrite 5 shining in centre, with transverse microreticulation; vestiture restricted to anterolateral portions; apical margin broadly arcuate. Ventrite 6 shining, devoid of vestiture, with transverse reticulation; apical margin broadly arcuate. Ventrite 7 shining, with long, internal anteriorly directed processes bearing broad apical apodemes, supporting dense musculature. Last tergite with broad apicomedial notch. Aedeagus (Fig. 2B) complex; main piece with an elongate process on right-hand side in ventral view, which is arcuate and paramere-like. Parameres attached just before mid-way on main piece; left paramere relatively large, with an expanded, setose apex; right paramere smaller, setae at right angles to shaft, left paramere partly obscured by angled process of main piece. Female. Largely as males; maxillary palpi with segments 3 and 4 less expanded; abdominal ventrites 5–6 with straight apical margins; ventrite 6 with dense row of irregular puncture close to apical margin, bearing fine recumbent yellow setae. Variation. Some variation in colour amongst the type series. Measurements. Holotype BL = 1.65 mm; EL = 1.05; EW = 0.80 mm. Paratype male BL = 1.65 mm; EL = 1.10; EW = 0.80 mm. Paratype females BL = 1.65–1.70 mm; EL = 1.05–1.10 mm; EW = 0.80–0.85 mm. Differential diagnosis. There are now 146 Hydraena known from the Afrotropical Region, of which only 50 are recorded from areas of tropical Africa south of the Sahara. Thirty-three of these were recently described from Cameroon by PERKINS (2022). Amongst known Afrotropical species, H. mulanje sp. nov. is readily distinguished by its broadly explanate elytral margins and aedeagal anatomy. The form of the aedeagus would apparently place the new species in Aedeagal Species Group 3 of Hydraenopsis Janssens, 1972 in PERKINS (2022), but the process adjacent to the right paramere is much larger in H. mulanje sp. nov. than in any of the described Cameroonian species. Etymology. Named in reference to the type locality. The specific epithet is a noun in the nominative case. Distribution and ecology. Known only from Mount Mulanje, an inselberg in southeast Malawi which reaches 3200 m, making it the highest mountain in the country (Fig. 4). Specimens were collected from a forested ravine on the south side of the mountain where they were sifted from leaf litter. Apparently a terrestrial species., Published as part of Bilton, David T., 2023, New species and new records of minute moss beetles from East Africa (Coleoptera: Hydraenidae), pp. 103-110 in Acta Entomologica Musei Nationalis Pragae 63 (1) on pages 106-107, DOI: 10.37520/aemnp.2023.004, http://zenodo.org/record/7887285, {"references":["PERKINS P. D. 2022: Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae). Zootaxa 5203: 1 - 66."]}

Several field surveys at 391 freshwater localities between 1985 and 2019 were undertaken in Morocco. Altogether, our field studies identified 67 species belonging to three genera (Hydraena, Limnebius, and Ochthebius), and representing 85.89% of the Hydraenidae fauna of the country. The species Hydraena exarata Kiesenwetter, 1866 is reported for the first time from Africa, and Ochthebius (Ochthebius) thermalis Janssens, 1965 and O. (Ochthebius) grandipennis Fairmaire, 1879 are here recorded for the first time from Morocco. These findings increased the number of Moroccan Hydraenidae to 78. Ochthebius semisericeus Saint-Claire Deville, 1914 and O. viridis Peyron, 1858 are excluded from the Moroccan fauna. Furthermore, the checklist presented in this work includes 15 Moroccan endemic, 19 Ibero-Maghrebian endemic and 8 Maghrebian endemic species. A biogeographical analysis shows that the Hydraenidae from Morocco are essentially Mediterranean (89.74%), while the Palaearctic elements (7.70%) and the species with wider distributions (2.56%) are less represented, highlighting the general limited dispersion capability of Hydraenidae compared to other water beetle families. The present study can serve as the basis for future progress in the knowledge of the Moroccan Hydraenidae.

Hydraena (Hydraenopsis) bahiana sp. nov. is described from Bahia State, Northeast Brazil, based on three specimens collected in pools at the headwater of a stream, 1,705 m. asl. The new species belongs to the Hydraena scintillabella subgroup of the leechi group. Description and diagnostic characters are offered; habitus photographs and line drawings of both male and female genitalia are provided. Habitat and distributional data of the new species are also included.

This catalogue lists 46 valid species included in 7 genera and two subfamilies of the family Hydraenidae (Coleoptera), recorded from India. The subfamily Hydraeninae accommodates 24 species (5 genera), and Ochthebiinae 22 species (2 genera). We include synonyms, type localities, type depositories, and distribution of the species. The Himalayan region supports the maximum diversity (31 species), followed by Deccan Peninsula (5 species), Western-Ghats (5 species), Northeast (4 species), Gangetic Plains (4 species), Semi-Arid (2 species), and Islands (one species).

O. (A.) exaratus Mulsant 1844 Originally described from Central France [différentes parties du midi de France ”]. I have examined specimens from England, France, Morocco, Portugal, and Spain, including the male genitalia (Fig. 3), to make certain that the specimens represent only one species, and to make certain that O. (A.) strangulatus Régimbart 1906 is a distinct species, not a junior synonym of O. (A.) exaratus Mulsant. Type specimens of O. (A.) exaratus Mulsant, including the male genitalia, should be examined to confirm my decisions. Type specimens will probably be in the Mulsant collection at the Paris Museum (MNHN)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 503, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172, {"references":["Regimbart, M. (1906) Voyage de M. Ch. Alluaud dans l'Afrique Orientale. Dytiscidae, Gyrinidae, Hydrophilidae. Annales de la Societe entomologique de France, 75, 235 - 278."]}

O. (A.) tenuipunctus Régimbart 1906 Members of the O. (A.) tenuipunctus species group are immediately recognized by the very smooth dorsum, especially the elytra (e.g., Fig. 2). O. (A.) tenuipunctus Régimbart was originally described from Kenya. Among the specimens available for this study from Kenya are two species in the O. (A.) tenuipunctus species group. Based on the description published by Orchymont (1929), one of these species has been determined to be O. (A.) tenuipunctus Régimbart. This decision needs to be verified by examining, including the male genitalia, type specimens of O. (A.) tenuipunctus Régimbart, which should be in the Régimbart collection at the Paris Museum (MNHN)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 503, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172, {"references":["Regimbart, M. (1906) Voyage de M. Ch. Alluaud dans l'Afrique Orientale. Dytiscidae, Gyrinidae, Hydrophilidae. Annales de la Societe entomologique de France, 75, 235 - 278."]}

O. (Aulacochthebius) scutatus, new species Figs. 1, 4, 10, 25 Type Material. Holotype (male): South Africa; “ S. Afr., Zululand, Mtubatuba—Dukuduku, 28°22′ S, 32°19′ E, 4.4.1974; E-Y: 319; shorewashing, pan; leg. Endrödy-Younga ” (TMSA). Paratypes (42): South Africa: KwaZuluNatal Province, Hluhluwe Game Res., (28°5′S, 32°4′E), 27.xi.1992, leg. Endrödy-Younga (#2861) (3 TMSA); As above, shorewashing, slow water, leg. Endrödy-Younga (#2862) (11 TMSA); Hluhluwe Game Reserve, (28°5′S, 32°4′E), 17.xi.1992, leg. Endrödy-Younga #2824 (#2824) (17 TMSA); Ndumu Game Reserve, (26°53′S, 32°16′E), 12.vi.1989, leg. Endrödy-Younga & Klimaszewski (#2612) (4 TMSA); Western Cape Province, Elandsdrift, (34°39′S, 19°53′E), 24.ii.1981, leg. Endrödy-Younga (#1747) (7 TMSA). Differential diagnosis. Differentiated from other members of the O. (A.) continentalis Group by the combination of the dorsum of head and pronotum microreticulate, setae sparse, and by the aedeagus. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.26/0.57; head width 0.36; pronotum length 0.29, width at base 0.25, width at hyaline border 0.50; elytra 0.75/0.57. Habitus as illustrated (Fig. 10). Dorsum dark brown except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded. Frons and clypeus microreticulate, dull, setae sparse, indistinct except longer and more numerous laterally. Labrum anterior margin arcuate in both sexes. Pronotum sparsely, finely setose, microreticulate, more distinctly so in impressions than on disc; anterior and posterior transverse impressions deep, anterior narrowly separated from shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression moderately deep, connecting anterior and posterior transverse impressions. Pronotum lateral hyaline borders wide, extended from posterior to anterior angles; sides of non-hyaline part with short, sparse, inconspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders narrow. Elytra wider than non-hyaline part of pronotum, posteriorly rounded, sides arcuate; ten seriate-punctate, punctures large, deep, intervals narrow, very finely microreticulate, dull; each puncture with granule at anterior margin, and conspicuous decumbent seta that arches over puncture, and attains base of following seta; lateral margin with row of very short, arcuate decumbent setae. Venter (Fig. 10): Mentum with sparse, moderately large setigerous punctures. Prosternum with midlongitudinal carina. Metaventrite tabella large, kite shaped, with anterior angle extended as carina; width ca. 0.56 width of metaventrite; slightly wider than long, lateral angles slightly rounded (ca. 71 degrees), anterior angle (not including carina) ca. 120 degrees), midline lengths above and below horizontal imaginary line through widest part as 3:5; surface with few random setigerious punctures, and each side with extremely shallow, non-punctate longitudinal impression, barely visible (not showing on figure), setae along posterior margins much longer than setae along anterior margins. Abdominal venter: first four ventrites bearing rather long hydrofuge pubescence; remaining ventrites glabrous, shining, with sparse setae. All tibiae with long, dense, spine-like setae, especially on mesotibiae. Etymology. Named in reference to the shield-shaped metaventral tabella. Distribution. Currently known from southern and northeastern South Africa (Fig. 25)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 520, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (A.) strangulatus Régimbart 1906 Orchymont (1929) placed O. (A.) strangulatus as a junior synonym of O. (A.) exaratus Mulsant. Although the synonymy is rejected herein, it is clear that O. (A.) strangulatus is a member of the O. (A.) exaratus species group. This species has a distinctive aedeagus (with paramere setae), and among the African study materials there are only two species that match the external morphology of the O. (A.) exaratus species group (the second species being O. (A.) copiosus n. sp.). I have examined, including the male genitalia, specimens from Kenya, collected near the type locality of O. (A.) strangulatus, in addition to specimens from Angola, Namibia, Nigeria, South Africa, Uganda, and Zimbabwe. Type specimens of O. (A.) strangulatus Régimbart, including the male genitalia, should be examined to confirm my decisions. Type specimens will probably be in the Régimbart collection at the Paris Museum (MNHN)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 503, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172, {"references":["Regimbart, M. (1906) Voyage de M. Ch. Alluaud dans l'Afrique Orientale. Dytiscidae, Gyrinidae, Hydrophilidae. Annales de la Societe entomologique de France, 75, 235 - 278."]}

O. (Aulacochthebius) tenuipunctus Régimbart Figs. 2, 4, 15, 27, 28, 29 Ochthebius tenuipunctus Régimbart 1906: 275 Type locality: Kenya: Lake Victoria, Winam Gulf [“Baie de Kavirondo ”]. Material examined (54): Benin: Dep. Atlantique, Ouidah, at sea level, (6°19′50.6′′N, 2°5′12.6′′E), 8.ii.2006, leg. Goergen, Komarek & Houngua (22) (6 NMW); Dep. Mono, Come, Dohi (village), (6°23′7.4′′N, 1°56′14.5′′E), 2.ii.2006, leg. Goergen, Komarek & Houngua (7) (42 NMW); Dep. Oueme, Porto Novo, Lopodji (village), (6°26′50.5′′N, 2°39′30.1′′E), 8.ii.2006, leg. Goergen, Komarek & Houngua (24) (2 NMW). Kenya: 10 mi. S. Nanyuki, (0°7′S, 37°5′E), 5.ii.1968, leg. P. J. Spangler (1 male NMNH). South Africa: Mpumalanga Province, Stn. VD 1, VAL 743BB, headwaters of Vaal River between Breyten & Lake Chrissie, headwater stream, marginalvegetation, 22.VII.1959, (26°17′S, 30°3′15′′E) (1 male AMG); Vaal R., Stn. V.D. 21, (26°49′10′′S, 30°08′00′′E), marginal vegetation, NIWR-VAL 884J (1 male AMG); Vaal River System, VAL Stn. 0894H (26°51′5′′S, 29°41′50′′E) (1 male AMG). Differential diagnosis. Differentiated from other members of the O. (A.) tenuipunctus Group by thecombination of the comparatively large size (ca. 1.40 mm), and by the aedeagus. Similar in size to O. (A.) plicicollis;distinguished therefrom by the shorter and shallower midlongitudinal impression of the pronotum, and by the aedeagus. Redescription. Size: specimen from Kenya (length/width, mm): body 1.40/0.63 (length to elytral apices); head width 0.37; pronotum length 0.30, width at base 0.24, width at hyaline border 0.57, width of lateral sclerotized lobes 0.44 at anterior, 0.42 at posterior; elytra 0.87/0.63. Habitus as illustrated (Fig. 15). Dorsum black, legs brown, hyaline borders of prothorax translucent to light yellowish. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow setigerouspunctures. Labrum anterior margin arcuate. Pronotal reliefs very smooth, with very sparse and very short setae; anterior and posterior transverseimpressions deep, anterior contiguous with shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression very shallow, extending from anterior transverse impression to ca. midlength. Pronotum anterior margin bisinuate. Pronotum lateral hyaline borders very wide, extended from posterior to anterior angles, outer margin markedly arcuate; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders very narrow. Elytra transversely convex, wider than hyaline part of pronotum, posteriorly acuminate, sides markedly arcuate; very smooth, with serial rows of very shallow, widely spaced punctures, each with very short seta; lateral margin with very long yellow setae, dense at and slightly behind humeral angle, sparse on remainder of margin; most of margin also with very dense, very short setae that extend outward from margin. Elytral apices truncate. Venter (Fig. 15): Tabella oval, slightly wider than long (as ca. 80:70), slightly convex; first four ventrites bearing rather long hydrofuge pubescence; remaining ventrites glabrous, shining, with sparse setae. Distribution. Currently known from Kenya and South Africa (Figs. 25, 29). Remarks. All three specimens from South Africa are dissected males. The aedeagi of these specimens do not differ significantly from that of the specimen of O. (Aulacochthebius) tenuipunctus from Kenya., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 529-530, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172, {"references":["Regimbart, M. (1906) Voyage de M. Ch. Alluaud dans l'Afrique Orientale. Dytiscidae, Gyrinidae, Hydrophilidae. Annales de la Societe entomologique de France, 75, 235 - 278."]}

O. (A.) alienus Orchymont 1929 Based on the original description, this species, which was described from Kenya, is another member of the O. (A.) tenuipunctus species group. Among the specimens available for this study from Kenya are two species in the O. (A.) tenuipunctus species group. Based on the description published by Orchymont (original 1929, redescription 1948), one of these species has been determined to be O. (A.) alienus Orchymont. This decision needs to be verified by examining, including the male genitalia, type specimens of O. (A.) alienus Orchymont, which should be in the Orchymont collection at the Brussels Museum (RBINS)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 503, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) flagellissimus, new species Figs. 1, 4, 11, 26 Type Material. Holotype (male): South Africa: Western Cape Province, “S. Afr.: S. W. Cape, Nuweberg, 10 km NE, 34°00′ S, 19°06′ E, shore washing, 13.xi.1973, leg. Endrödy-Younga (#240)” (TMSA). Paratypes (111): Same data as holotype (54 TMSA). South Africa: Northern Cape Province, Temp pools on R27 ca 2 km E of Vanrhynspas—sandy soils, (31°23′.96′′S, 19°1′21.72′′E), 27.ix.2011, leg. D. T. Bilton (6 DTBC); Western Cape Province, Paarl Vlei on Wemmershoek road; FRW 115P, (34°4′S, 19°0′E), 14.ix.1955, leg. unknown (1 AMG); S. W. Cape, Nuweberg, 10km NE, (34°3′S, 19°6′E), 13.xi.1973, leg. Endrödy-Younga (#239) (50 TMSA). Other material: Same data as holotype (non-types in alcohol, 880 TMSA); S. W. Cape, Nuweberg, 10km NE, (34°3′S, 19°6′E), 13.xi.1973, leg. Endrödy-Younga (#239) (non-types in alcohol, 125 TMSA). Differential diagnosis. Differentiated from other similar members of the O. (A.) continentalis Group by the combination of the abdominal venter with shining large suboval glabrous area bearing sparse, rather long setae, remainder of ventrites with hydrofuge pubescence, and by the aedeagus. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.10/0.50; head width 0.33; pronotum length 0.27, width at base 0.23, width at hyaline border 0.45; elytra 0.64/0.50. Habitus as illustrated (Fig. 11). Dorsum dark brown to black except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded. Frons and clypeus moderately densely finely punctate, interstices shining. Labrum anterior margin arcuate in both sexes. Pronotum moderately densely, finely setose, shining; anterior and posterior transverse impressions deep, anterior narrowly separated from shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression narrow, shallow, connecting anterior and posterior transverse impressions. Pronotum lateral hyaline borders wide, extended from posterior to anterior angles; sides of non-hyaline part with short, sparse, inconspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders narrow. Elytra wider than non-hyaline part of pronotum, posteriorly rounded, sides arcuate; ten seriate-punctate, punctures moderately large, deep, intervals shining, ca. same width as punctures; each puncture with distinct granule at anterior margin, and decumbent seta that arches over puncture, attaining base of following seta; lateral margin with row of very short, arcuate decumbent setae. Venter (Fig. 11): Mentum with sparse, moderately large setigerous punctures. Prosternum with very low midlongitudinal carina. Metaventrite tabella large, diamond shaped, width ca. 0.6 width of metaventrite, slightly longer than wide, lateral angles sharp (ca. 68 degrees), anterior angle cariniform (anterior angle ca. 112 degrees), surface with few random setigerious punctures, mostly in anterior 0.5, setae along posterior margins longer than setae along anterior margins. Abdominal venter with shining large suboval glabrous area bearing sparse, rather long setae, remainder of ventrites with hydrofuge pubescence. Etymology. Named in reference to the incredibly long aedeagal flagellum, which is nearly twice as long as the beetle’s body. Distribution. Currently known from southern and southwestern South Africa (Fig. 26)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 520-521, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) nigeriensis, new species Figs. 2, 4, 19, 28 Type Material. Holotype (male): “ NIGERIA: Oyo Prov., Ogbomosho, 12-13.ii.1949. B. Malkin coll.”; [8°8′N, 4°15′E] (NHMUK). Paratypes: Same data as holotype (12 NHMUK). Differential diagnosis. Differentiated from other similar members of the O. (A.) tenuipunctus Group by the combination of the slightly smaller size, and by the aedeagus. Very similar in characters to O. (A.) alienus and O. (A.) solitarius; reliable determinations will require careful examination of the male genitalia. Description. Size: holotype (length/width, mm): body 1.16/0.57 (length to elytral apices); head width 0.35; pronotum length 0.30, width at base 0.22, width at hyaline border 0.55, width of lateral sclerotized lobes 0.42 at anterior, 0.41 at posterior; elytra 0.76/0.57. Habitus as illustrated (Fig. 19). Body longitudinally and transversely very convex. Dorsum brown to dark brown except hyaline borders of prothorax translucent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow setigerous punctures. Labrum anterior margin arcuate. Pronotal reliefs very smooth, with very sparse and very short setae; anterior and posterior transverse impressions deep, anterior contiguous with shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression obsolete, almost imperceptible, only present at anterior transverse impression. Pronotum anterior margin bisinuate. Pronotum lateral hyaline borders very wide, extended from posterior to anterior angles, outer margin strongly arcuate; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders very narrow. Elytra slightly wider than hyaline part of pronotum, posteriorly acuminate, sides markedly arcuate; very smooth, non-punctate, with sparse, very short, widely separated serial or subserial setae; lateral margin with very dense, very short setae that extend outward from margin in dry specimens Abdominal venter (Fig. 19): first four ventrites bearing rather long hydrofuge pubescence; remaining ventrites glabrous, shining, with sparse setae. Etymology. Named in reference to the known distribution. Distribution. Currently known only from Nigeria (Fig. 28)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 537, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) latissimus, new species Figs. 2, 4, 17, 23 Type Material. Holotype (male): South Africa; “ S. Afr., c. Transvaal, Roodeplaat Dam, 25°37′S, 28°23′E, 14.8.1974, E-Y: 359, shore washing, leg. A. Strydom ” (TMSA). Paratypes (184): South Africa: Same data as holotype (15 TMSA); Cape Prov., Wilderness NP, car catcher, (33°59′S, 22°38′E), 13-14.xi.1997, leg. B. & M. Uhlig (6 ZHMB); Eastern Cape Province, De Hoop NR; Carex sievings, (34°27.2′S, 20°24.2′E), 10.xi.1997, leg. M. Uhlig (1 ZHMB); Wilderness NP, Langvlei; Malachite bird hide, Juncus krausi and bush litter sievings, (33°59′S, 22°41′6′′E), 30.xi.1996, leg. B. & M. Uhlig (3 ZHMB); KwaZulu-Natal Province, Hluhluwe Game Res., (28°5′S, 32°4′E), 19.xi.1992, leg. Endrödy-Younga (#2832) (1 TMSA); same locality, 27.xi.1992, leg. Endrödy-Younga (#2862) (6 TMSA); same locality, 27.xi.1992, leg. Endrödy-Younga (#2861) (7 TMSA); Hluhluwe Game Reserve, (28°5′S, 32°4′E), 17.xi.1992, leg. Endrödy-Younga #2824 (#2824) (32 TMSA); Karkloof Grassveld, (29°19′S, 30°15′E), 12.ix.1989, leg. Endrödy-Younga & Klimaszewski (#2753) (1 TMSA); Mtubatuba, (28°22′S, 32°19′E), 4.iv.1974, leg. Endrödy-Younga (#318) (1 TMSA); Zululand, Dukuduku For. Sta., (28°22′S, 32°19′E), 4.iv.1974, leg. Endrödy-Younga (#323) (1 TMSA); Mpumalanga Province, Bundu Inn, (25°28′S, 28°55′E), 24.iii.1974, leg. Endrödy-Younga (#304) (8 TMSA); Nelshoogte galery forest below St., (25°51′S, 30°53′E), 2.xii.1986, leg. Endrödy-Younga (#2343) (3 TMSA); S. Transvaal, Roberts Drift, Vaal R., (27°2′S, 29°2′E), 8.x.1973, leg. EndrödyYounga (#190) (3 TMSA); Western Cape Province, 8 mi. E. Wilderness, (33°58′S, 22°43′E), 13.iii.1968, leg. P. J. Spangler (3 NMNH); De Hoop Nat. Res., (34°27′S, 20°24′E), 17.xi.1993, leg. M. Uhlig (2 ZHMB); SW Cape, Verlorevlei Farm, (32°19′S, 18°22′E), 28.viii.1981, leg. Endrödy-Younga (#1857) (90 TMSA). Differential diagnosis. Differentiated from most other members of the O. (A.) tenuipunctus Group by the combination of the small size and wide body form, and by the aedeagus. Differentiated from the similarly wide and small species O. (A.) perlaevis by the very irregular elytral serial rows of punctures, and by the aedeagus. Description. Size: holotype (length/width, mm): body 1.19/0.55 (length to elytral apices); head width 0.34; pronotum length 0.30, width at base 0.22, width at hyaline border 0.60, width of lateral sclerotized lobes 0.45 at anterior, 0.22 at posterior; elytra 0.67/0.55. Habitus as illustrated (Fig. 17). Dorsum dark brown to black except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow setigerous punctures. Labrum anterior margin arcuate in both sexes. Pronotal reliefs very smooth, with very sparse and very short setae; anterior and posterior transverse impressions deep, anterior contiguous with shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression absent. Pronotum lateral hyaline borders very wide, extended from posterior to anterior angles, outer margin strongly arcuate; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior hyaline border moderately wide; posterior hyaline border narrow. Elytra slightly wider than non-hyaline part of pronotum, posteriorly acuminate, sides markedly arcuate; very smooth, non-punctate, with sparse, very short, random setae; lateral margin with dense, very long setae that extend outward from margin in dry specimens. Venter (Fig. 17): Tabella oval to suboval, very slightly angulate anteriorly, very slightly wider than long, slightly convex; first four ventrites bearing rather long hydrofuge pubescence; remaining ventrites glabrous, shining, with sparse setae. Males slightly smaller than females: males ca. 1.10–1.25 mm; females ca. 1.15–1.30 mm. Etymology. Named in reference to the very wide lateral hyaline border of the pronotum, and the long and numerous lateral setae of the elytra. Distribution. Currently known from southern and eastern South Africa (Fig. 23)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 535-536, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) copiosus, new species Figs. 1, 3, 8, 22 Type Material. Holotype (male): South Africa; “ S. Afr., S. Transvaal, Roberts Drift: Vaal R., 27°2′ S, 29°2′ E, 8.10.1973, E-Y: 190, sifted flood debris, leg. Endrödy-Younga ” (TMSA). Paratypes (2,217 card mounted paratypes) (3,194 non-types in alcohol = “nta” below). Same data as holotype (50 + 1694 nta TMSA). Angola: 20 km. E. Luanda, Luanda-Catete Highway, (8°50′S, 13°22′E), 9.x.1949, leg. B. Malkin (5 BMNH); Namibia: East Caprivi: Katima Mulilo, lux, (17°29′S, 24°17′E), 3-8.iii.1992, leg. M. Uhlig (3 ZMHB). South Africa: Eastern Cape Province, 11 mi. W. Komga, (32°36′S, 27°43′E), 20.iii.1968, leg. P. J. Spangler (2 NMNH); 16 mi. N. Grahamstown, (33°18′S, 26°32′E), 17.iii.1968, leg. P. J. Spangler (3 NMNH); Btwn. Lady Frere & Cala, farm dam, elev. 1067 m (31°40′3.72′′S, 27°3′21.24′′E), 26.iii.1954, leg. J. Balfour-Browne (Stn. No. 100) (1 BMNH); Grahamstown, (33°18′S, 26°32′E), 1-30.v.1939, leg. J. Omer-Cooper (1 BMNH); Grahamstown, Teafontein Farm, (33°18′S, 26°32′E), 5.viii.1939, leg. J. Omer-Cooper (4 BMNH); Little Karroo, Baviaanskloof N vally, (33°37′S, 24°15′E), 28.x.1993, leg. Endrödy-Younga (#2917) (13 TMSA); Albany, Gowies Kloof, 6.viii.1939, leg. Omer-Cooper (2 BMNH); Free State Province, Vredefort, nr. Homing Spruit, (27°1′S, 27°23′E), 29.viii.1949, leg. J. Omer-Cooper (1 BMNH); KwaZulu-Natal Province, Hluhluwe Game Res., (28°5′S, 32°4′E), 27.xi.1992, leg. Endrödy-Younga (#2861) (3 TMSA); Hluhluwe Game Reserve, (28°5′S, 32°4′E), 17.xi.1992, leg. Endrödy-Younga #2824 (#2824) (2 TMSA nta); Mtubatuba, (28°22′S, 32°19′E), 24–25.iii.1968, leg. P. J. Spangler (1 NMNH); same locality, 4.iv.1974, leg. Endrödy-Younga (#324) (7 TMSA); same locality, 4.iv.1974, leg. Endrödy-Younga (#318) (5 TMSA nta); same locality, 4.iv.1974, leg. Endrödy-Younga (#319) (8 TMSA); Ndumu Game Reserve, (26°53′S, 32°16′E), 12.vi.1989, leg. Endrödy-Younga & Klimaszewski (#2612), shore washing, fresh water (170, + 72 nta TMSA;); same locality, 12.vi.1989, leg. Endrödy-Younga & Klimaszewski (#2613), shore washing, salty water (124 + 984 nta TMSA); St. Lucia iSimangaliso Wetland Eastern Shores, (28°20′59.02′′S, 32°25′50.59′′E), D. T. Bilton leg (2 DTBC); iSimangaliso Wetland Park, False Bay site 3, 31/i/2015, (27°57′31.33′′S, 32°21′42.15′′E), D. T. Bilton leg (1 DTBC); Zululand, Dukuduku For. Sta., (28°22′S, 32°19′E), 4.iv.1974, leg. Endrödy-Younga (#323) (25 + 224 nta TMSA); Limpopo Province, N. Transvaal, Mmabolela estate, (22°40′S, 28°15′E), 6.iii.1973, leg. Endrödy-Younga (#13) (9 TMSA); Mpumalanga Province, Albany Museum catalog; Vaal River System (VAL): 267N, 344B, 407CD, 411A, 443T, 496E, 506J, 511U, 552V, 680K, 680R, 750B, 753R, 822E, 825H, 889C, 894H, 894H X3, 1126 N, 1212E, 1296L, 1.i.-29.xii.1960, collr. unknown (26 AMG); c. Transvaal, Roodeplaat Dam, (25°37′S, 28°23′E), 14.viii.1974, leg. Endrödy-Younga (#359) (34 TMSA); Kruger Nat. Park, Pafuri, (22°25′S, 31°17′E), 12.ii.1994, leg. EndrödyYounga (#2998) (32 TMSA); Kruger Nat. Pk., Letaba River below dam, (23°46′S, 31°30′E), 1.iii.1995, leg. Endrödy-Younga (#3122) (18 TMSA); Kruger National Park, Pafuri, around, (22°25′S, 31°12′E), 1.ii.1994, leg. Endrödy-Younga (#2969) (6 TMSA); Kruger National Park, Skukuza, Sabie River, (24°57′S, 30°42′E), 22.ii.1995, leg. Endrödy-Younga (#3110) (4 TMSA); Mathlakusapan, (22°37′S, 31°22′E), 4.ii.1997, leg. Endrödy-Younga (#2991) (32 + 113 nta TMSA); nr. Standerton, (26°58′S, 29°13′E), 8.iv.1954, leg. J. Balfour-Browne (161) (14 BMNH); Natal Prov., Ngagane River, marginal vegetation, 1.vi.-29.viii.1974, leg. CSIR Water Research (16 AMG); Northern Cape Province, Richtersveld N.P., Richterberg Camp, (28°15′2′′S, 17°12′48′′E), 9.ix.2004, leg. M. & B. Uhlig (1 ZMHB); Western Cape Province, Little Karroo, Raubenheimer Dam, (33°25′S, 22°19′E), 21.x.1993, leg. EndrödyYounga (#2889) (4 TMSA); Stream beside R339 road in Prince Alfred’s Pass, ca. 10 km S of Avontuur, (33°45′S, 23°10′E), 20.ix.2009, leg. D. T. Bilton (2 DTBC). Zimbabwe: Gwai River, (18°40′S, 27°13′E), 3.iv.1968, leg. P. J. Spangler (1 NMNH). Differential Diagnosis. Similar externally to O. (A.) exaratus and O. (A.) strangulatus. In addition to the differences in the aedeagus of the three species (given below), O. (A.) copiosus differs in the following characters: 1) slightly larger body size (ca. 1.40 mm vs. 1.10 to 1.30); 2) setae on margins of pronotum and elytra distinctly denser, longer, and extend outward more prominently; 3) elytral punctures more widely separated one from the other, and lacking minute granules at the anterior margin of the punctures. The aedeagi of the three species differ as follows (Fig. 3): 1) the distal ½ of the main-piece is shaped differently in the three species; 2) the apex of the main-piece is truncate in O. (A.) exaratus, but rounded in the other two species; 3) the flagellum, especially the shape of the first fold, and the length of the flagellum, differ in the three species. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.38/0.62; head width 0.35; pronotum 0.29/0.48; elytra 0.86/0.62. Habitus as illustrated (Fig. 8). Dorsum dark brown except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow finely setigerous punctures. Labrum apicomedially produced in male, rounded in female. Pronotal reliefs very smooth, with very sparse and very short indistinct setae; anterior and posterior transverse impressions deep, anterior narrowly separated from transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression deep, extended from anterior to posterior impression. Pronotum lateral hyaline borders moderately wide, present only in angulation behind lateral lobes; sides of lateral lobes with conspicuous long setae that extend outward from cuticle in dry specimens; anterior hyaline border moderately wide; posterior hyaline border narrow. Elytra smooth, ten seriate-punctate, punctures small, each with fine decumbent seta, setae longer and more conspicuous laterally and apically than on disc; setae on lateral margins dense and long, extending outward from cuticle in dry specimens. Venter (Fig. 8): Mentum with sparse, small setigerous punctures. Prosternum with very low midlongitudinal subcarina. Metaventrite tabella large, angulate anteriorly and laterally, length slightly less than width (ratio ca. 5:6); ratio of length above and below horizontal imaginary line through greatest width ca. 6:7; lateral angles slightly rounded; surface with very few, very fine punctures; tabella bordered by moderately long setae. Abdominal venter: first two ventrites and antero-lateral margin of third with hydrofuge pubescence, remainder of ventrites shining, with very sparse setae. Distribution. Currently known from Angola, Namibia, South Africa, and Zimbabwe (Fig. 22). Etymology. Named in reference to the copious number of specimens., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 517-518, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) exaratus Mulsant Figs. 1, 3, 6 Ochthebius exaratus Mulsant 1844: 67 Discussion. Refer to the discussion of O. (A.) copiosus n. sp. Differential Diagnosis. Refer to the differential diagnosis of O. (A.) copiosus n. sp. Redescription. Size: specimen from Portugal (length/width, mm): body (length to elytral apices) 1.28/0.57; head width 0.34; pronotum 0.27/0.43; elytra 0.78/0.57. Habitus as illustrated (Fig. 6). Dorsum dark brown except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow finely setigerous punctures. Labrum apicomedially produced in male, rounded in female. Pronotal reliefs very smooth, with very sparse and very short indistinct setae; anterior and posterior transverse impressions deep, anterior narrowly separated from transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression moderately deep, extended from anterior to posterior impression.Pronotum lateral hyaline borders wide, present only in angulation behind lateral lobes; sides of lateral lobes with short setae that extend outward from cuticle in dry specimens; anterior hyaline border moderately wide; posterior hyaline border narrow. Elytra smooth, ten seriate-punctate, punctures small; each puncture with very fine very short seta, which lies flat on cuticle; minute granule at anterior margin of each puncture, more obvious on disc; setae on lateral margins only moderately dense and only moderately long, recumbent in dry specimens. Venter (Fig. 6): Mentum with sparse, small setigerous punctures. Prosternum with very low midlongitudinal subcarina. Metaventrite tabella large, angulate anteriorly and laterally, length slightly less than width (ratio ca. 5:6); ratio of length above and below horizontal imaginary line through greatest width ca. 3:4; lateral angles slightly rounded; surface with very few, very fine punctures; tabella bordered by moderately long setae. Abdominal venter: first two ventrites and antero-lateral margin of third with hydrofuge pubescence, remainder of ventrites shining, with very sparse setae. Distribution. Palearctic., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 507-516, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) libertarius Aguilera, Ribera and Hernando Figs. 1, 14, 30 Aulacochthebius libertarius Aguilera, Ribera and Hernando 1998: 630. Material examined: Ethiopia: Oromia, 5 km SW Addis Alem, 44 km W Addis Abeba, named Berga River, 2140 m a.s.l., (9°1′27.64′′N, 38°21′7.82′′E), 25.ii.2014, leg. M. A. Jäch (27) (6 NMW). Morocco Aït-Baha 20.vii.1997 / Oued Aït Baha 30°03′45′′N 9°06′93′′W / leg. Aguilera, Ribera & Hernando (paratype male, NMW). Senegal: Village Sare Sara, 21 km ESE Kolda, 19.00–21.00, 6.iii.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (2 LUM). O. (Aulacochthebius) libertarius was originally described from Morocco. I have examined specimens, including males for each locality, from Morocco (a male paratype), Ethiopia, and Senegal. This species is clearly a member of the O. (A.) continentalis Group. It has the basic pronotal shape and the strongly punctate elytral series present in the group. The aedeagus of O. (A.) libertarius as figured in Aguilera et al. (1998) is unfortunately very inaccurate: it is depicted as being sharply pointed at the distal end of the main-piece, and the main-piece is drawn as being symmetrical. High magnification shows that the distal end is in fact truncate, and the main-piece, like others in the subgenus, is asymmetrical and more complicated in details (Fig. 14). The aedeagus is somewhat similar to that of O. (A.) solitarius n. sp., but differs in details, and the habitus of the two species (Figs. 14, 18) are quite different from one another; the two species are in different species groups. Differential diagnosis. Differentiated from other similar members of the O. (A.) continentalis Group by the combination of the dorsum of head and pronotum with very sparse, very fine setae, the pattern of the hydrofuge pubescence on the abdominal ventrites, and by the aedeagus (Fig. 14)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 528-529, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172, {"references":["Aguilera, P., Ribera, I. & Hernando, C. (1998) Notes on the Palaearctic species of Aulacochthebius, with a description of A. libertarius sp. n. from the Moroccan Anti Atlas (Coleoptera: Hydraenidae). European Journal of Entomology, 95, 629 - 637."]}

O. (Aulacochthebius) solitarius, new species Figs. 2, 4, 18, 29 Type Material. Holotype (male): South Africa: Western Cape Province, “Cape T. Raffray” [Cape Town, 33°55′S, 18°25′E] (NHMUK). Differential Diagnosis. Differentiated from other similar members of the O. (A.) tenuipunctus Group by the combination of the slightly smaller size, and by the aedeagus. Very similar in characters to O. (A.) alienus and O. (A.) nigeriensis; reliable determinations will require careful examination of the male genitalia. Description. Size: holotype (length/width, mm): body 1.25/0.65 (length to elytral apices); head width 0.39; pronotum length 0.31, width at base 0.24, width at hyaline border 0.59, width of lateral sclerotized lobes 0.48 at anterior, 0.44 at posterior; elytra 0.85/0.65. Habitus as illustrated (Fig. 18). Body longitudinally and transversely very convex. Dorsum brown to dark brown except hyaline borders of prothorax translucent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow setigerous punctures. Labrum anterior margin arcuate. Pronotal reliefs very smooth, with very sparse and very short setae; anterior and posterior transverse impressions deep, anterior contiguous with shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression absent. Pronotum anterior margin bisinuate. Pronotum lateral hyaline borders very wide, extended from posterior to anterior angles, outer margin strongly arcuate; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders narrow. Elytra slightly wider than hyaline part of pronotum, posteriorly acuminate, sides markedly arcuate; very smooth, non-punctate, with sparse, very short, widely separated serial or subserial setae; lateral margin with very dense, very short setae that extend outward from margin in dry specimens Venter (Fig. 18): Tabella oval to suboval, very slightly angulate anteriorly, slightly wider than long, slightly convex; first four ventrites bearing rather long hydrofuge pubescence; remaining ventrites glabrous, shining, with sparse setae. Etymology. Named in reference to the very restricted known distribution. Distribution. Currently known only from the type locality, Cape Town (Fig. 29)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 536-537, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) continentalis Orchymont Figs. 1, 4, 5, 9, 24, 27 O. (Aulacochthebius) continentalis Orchymont 1929: 196 Type locality: “ Afrique Orientale Anglaise ” [i.e., Kenya] Material examined (175): Angola: Pediva, ca. 30 mi. E. of Porto Alexandre, (16°17′4.2′′S, 12°33′46.8′′E), 26- 27.iv.1954, leg. J. Balfour-Browne (302) (22 NHMUK); same locality, 27.iv.1954, leg. J. Balfour-Browne (303) (2 NHMUK); Tampa, elev. 1219 m (15°30′S, 13°27′E), 15.vi.1954, leg. J. Balfour-Browne (274) (8 NHMUK); Vana e Lombe, near Tampa, (15°30′S, 13°30′E), 14.vi.1954, leg. J. Balfour-Browne (269) (3 NHMUK); Giraul, 5 mi. N. Mocamedes, sea level, in small sandy pools above beach, Stn. No. 282, (15°11′52.08′′S, 12°9′27.36′′E), 20.vi.1954, leg. J. Balfour-Browne (282) (12 NHMUK). Kenya: Kilifi Co., Kaloleni, 1.7km W of along road C107, KEN 16-33, 3.8148S 39.6149E, 181m, 29.I.2016, Large pond with sedge at edges as part of stream, 29.i.2016, leg. J. Bergsten & O. Bistrom (1 male KNM); Kaloleni, road C107, KEN 16-32, 3.8155S 39.6229E, 174m, 29.i.2016, leg. J. Bergsten & O. Bistrom (1 male, 2 females KNM); Taita _ Taveta Co., Gimba village, W side of Sagalla, Taita Hills, KEN 16-35, 3.4421S 38.55.77E, 653m, 30.I.2016, Partly dry streambed with pools and hygropetric sites over bedrock, 30.i.2016, leg. J. Bergsten & O. Bistrom (1 female KNM). Namibia: Kaokoveld, Kunene River, Swartbooisdrift, (17°19′S, 13°49′E), 10.ii.1975, leg. Endrödy-Younga (#645) (3 TMSA). South Africa: Eastern Cape Province, Transkei: Qora River, (32°16′S, 28°47′E), 2.iii.1985, leg. Endrödy-Younga (#2179) (2 TMSA); KwaZulu-Natal Province, Hluhluwe Game Res., (28°5′S, 32°4′E), 19.xi.1992, leg. Endrödy-Younga (#2832) (10 TMSA); same locality, 27.xi.1992, leg. Endrödy-Younga (#2861) (3 TMSA); same locality, 27.xi.1992, leg. Endrödy-Younga (#2862) (9 TMSA); Hluhluwe Game Reserve, (28°5′S, 32°4′E), 17.xi.1992, leg. Endrödy-Younga #2824 (#2824) (23 TMSA); Mtubatuba, (28°22′S, 32°19′E), 4.iv.1974, leg. Endrödy-Younga (#318) (4 TMSA); Ndumu Game Reserve, (26°53′S, 32°16′E), 12.vi.1989, leg. Endrödy-Younga & Klimaszewski (#2612) (2 TMSA); Limpopo Province, N. Transvaal, Waterberg, Farm 223, Mogol River, (24°11′S, 27°50′E), 13.ii.1976, leg. A. Strydom, Endrödy-Younga (#1039) (17 TMSA); Mpumalanga Province, Bundu Inn, (25°28′S, 28°55′E), 24.iii.1974, leg. Endrödy-Younga (#304) (8 TMSA); c. Transvaal, Roodeplaat Dam, (25°37′S, 28°23′E), 14.viii.1974, leg. Endrödy-Younga (#359) (20 TMSA); Kruger Nat. Pk., Letaba River below dam, (23°46′S, 31°30′E), 1.iii.1995, leg. Endrödy-Younga (#3122) (4 TMSA); Nelshoogte galery forest below St., (25°51′S, 30°53′E), 2.xii.1986, leg. Endrödy-Younga (#2343) (1 TMSA). Differential diagnosis. Differentiated from other members of the O. (A.) continentalis Group by the combination of the metaventral tabella surface on each side with slightly oblique longitudinal shallow groove with setigerous punctures, and by the aedeagus. Redescription. Size: specimen from South Africa (length/width, mm): body (length to elytral apices) 1.30/0.62; head width 0.38; pronotum length 0.30, width at base 0.27, width at hyaline border 0.54; elytra 0.78/0.62. Habitus as illustrated (Fig. 9). Dorsum dark brown to black except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded. Frons and clypeus densely punctate, rugulose, densely setose. Labrum anterior margin arcuate in both sexes. Pronotum densely setose, moderately coarsely punctate except finely punctate on disc; anterior and posterior transverse impressions deep, anterior narrowly separated from shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression deep, connecting anterior and posterior transverse impressions. Pronotum lateral hyaline borders wide, extended from posterior to anterior angles; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders narrow. Elytra wider than non-hyaline part of pronotum, posteriorly rounded, sides arcuate; ten seriate-punctate, punctures large, deep, intervals narrow; each puncture with granule at anterior margin, and conspicuous decumbent seta that arches over puncture; lateral margin with row of short, arcuate setae that extend outward from margin in dry specimens. Venter (Fig. 9): Mentum with sparse, moderately large setigerous punctures. Prosternum with very low midlongitudinal carina. Metaventrite tabella large, crown shaped, width ca. 0.56 width of metaventrite, slightly wider than long (ratio ca. 48:43), lateral angles slightly rounded, anterior angle prolonged as distinct carina that attains mesoventral intercoxal process; surface on each side with slightly oblique longitudinal shallow groove with setigerous punctures, area between grooves with few random setigerious punctures; setae along posterior margins longer than setae along anterior margins.Abdominal venter: first two ventrites and anterior margin and lateral areas of third with hydrofuge pubescence, remainder of ventrites dull, microreticulate, with sparse setae; setae longer on last ventrite (male). Remarks. The specimen imaged (Fig. 9) has the following locality data: Kruger Nat. Pk., Letaba River below dam, (23°46′S, 31°30′E), 1.iii.1995, leg. Endrödy-Younga (#3122). Distribution. Currently known from Angola, Kenya, Namibia, and South Africa (Figs. 23, 26)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 518-519, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

O. (Aulacochthebius) strangulatus Régimbart, new status Figs. 1, 3, 7, 27, 28 Ochthebius strangulatus Régimbart 1906: 274 O. (Aulacochthebius) exaratus Mulsant; Orchymont 1948. Misidentification. Type locality: Kenya (Maji ya Chumvi [“ Maji-Chumvi ”]; Samburu). Material examined (51): Benin: Dep. Mono, Come, Dohi (village), (6°23′7.4′′N, 1°56′14.5′′E), 2.ii.2006, leg. Goergen, Komarek & Houngua (7) (1 NMW); Dep. Mono, Lakossa, Doukonta (village), ca. 40 m a.s.l., (6°40′21.3′′N, 1°41′33.5′′E), 2.ii.2006, leg. Goergen, Komarek & Houngua (9) (1 NMW); Dep. Zou, Zogbodome, Lokoli (forest), Hianzoun riv., (7°3′N, 2°15′E), 3.ii.2006, leg. Goergen, Komarek & Houngua (14) (2 NMW). Burkina Faso: Obire, UV light trap, 15.ii.1995, leg. J. F. Cornell (7 NMW). Gambia: Outside Abuko Nature Reserve at Water Works, 18.30–21.00, 4.xi.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (1 LUM); River Tanji, 3 km SW Brufut, 19.00–21.00, 28.ii.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (2 LUM). Ghana: Northern region, Nabogo, 40 km N of Tamale, 21.i.1970, leg. S. Endrödy-Younga (Nr. 410) (6 HNHM); Nyankpala, 10.ii.1970, leg. S. Endrödy-Younga (3 TMSA). Kenya: Kilifi Co., Kaloleni, road C107, KEN 16-32, 3.8155S 39.6229E, 174m, 29.I.2016, Pools in dry streambed, in open landscape, 29.i.2016, leg. J. Bergsten & O. Bistrom (1 KNM); Killfi Co., Tributary to Galana river, elev. 6 m (3°8′15.72′′S, 40°5′53.16′′E), 28.i.2016, leg. J. Bergsten & O. Bistrom (KEN 16-30) (8 KNM). Mali: Mopti, Niger river, (14°30′N, 4°12′W), 21.ii.2000, leg. Komarek & Mayer (21-1) (2 NMW); San, Bani River, (13°18′N, 4°54′W), 22.ii.2000, leg. Komarek & Mayer (22-1) (2 NMW). Nigeria: Argungu, NW State, 22.xii.1974, leg. J. T. Medler (6 NMNH); Oyo Provence, Ogbomosho, (12-13)- II-1949, B. Malkin, (8°8′N, 4°15′E) (9 NHMUK). Senegal: 3 km SSW Toubakouta, 10 km S Ziguinchor, 19.00–22.00, 4.iii.1977, leg. Cederholm — Danielsson — Hammarstedt — Hedquist — Samuelsson (2 LUM). Uganda: Queen Elizabeth National Park, (0°8′14′′S, 30°2′28′′E), 2.v.1968, leg. P. J. Spangler (1 NMNH). Discussion. Orchymont (1929) suggested that O. (A.) strangulatus was a junior synonym of O. (A.) exaratus, under the section on O. (A.) exaratus in a “Tableau des Espèces” including the phrase [“(? strangulatus Reg.)”]. Later, Orchymont (1948) effectively removed the “?” by expressing the view that there is a transition in dorsal characters from O. (A.) exaratus to O. (A.) strangulatus, and cited a male from Nairobi as being “un exemplaire formant passage à strangulatus.” The catalogue of Hansen (1998) included strangulatus as one of the synonyms of O. (A.) exaratus. As is discussed in the O. (A.) exaratus section on types, the aedeagi of O. (A.) exaratus and (A.) strangulatus clearly differ, and represent two species. There are also external differences, mostly pertaining to the distributions and lengths of setae. Differential Diagnosis. Refer to the differential diagnosis of O. (A.) copiosus n. sp. Redescription. Size: specimen from Kenya (length/width, mm): body (length to elytral apices) 1.12/0.54; head width 0.32; pronotum 0.23/0.40; elytra 0.70/0.54. Habitus as illustrated (Fig. 7). Dorsum dark brown except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded, smooth. Clypeus with very few, very shallow finely setigerous punctures. Labrum apicomedially produced in male, rounded in female. Pronotal reliefs very smooth, with very sparse and very short indistinct setae; anterior and posterior transverse impressions deep, anterior narrowly separated from transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression deep, extended from anterior to posterior impression. Pronotum lateral hyaline borders moderately wide, present only in angulation behind lateral lobes; sides of lateral lobes with short setae that extend outward from cuticle in dry specimens; anterior hyaline border moderately wide; posterior hyaline border narrow. Elytra smooth, ten seriate-punctate, punctures small; on disc each puncture with very fine very short almost imperceptible seta, which lies flat on cuticle, setae more conspicuous and longer laterally and at elytral apices; minute granule at anterior margin of each puncture, more obvious on disc; setae on lateral margins only moderately dense and only moderately long, in dry specimens extending outward from cuticle on in anterior ¼ to 1/3, otherwise mostly lying flat on cuticle. Venter (Fig. 7): Mentum with sparse, small setigerous punctures. Prosternum with very low midlongitudinal subcarina. Metaventrite tabella large, angulate anteriorly and laterally, length slightly less than width (ratio ca. 7:9); ratio of length above and below horizontal imaginary line through greatest width ca. 3:4; lateral angles slightly rounded; surface with very few, very fine punctures; tabella bordered by moderately long to long setae. Abdominal venter: first two ventrites and antero-lateral margin of third with hydrofuge pubescence, remainder of ventrites shining, with very sparse setae. Distribution. Currently known from Kenya, Nigeria, and Uganda (Figs. 26, 27)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 516-517, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172, {"references":["Regimbart, M. (1906) Voyage de M. Ch. Alluaud dans l'Afrique Orientale. Dytiscidae, Gyrinidae, Hydrophilidae. Annales de la Societe entomologique de France, 75, 235 - 278.","Hansen, M. (1998) World Catalogue of Insects. Vol. 1. Hydraenidae (Coleoptera). Apollo Books, Stenstrup, 168 pp."]}

O. (Aulacochthebius) persetosus, new species Figs. 1, 4, 12, 26 Type Material. Holotype (male): “ SOUTH AFRICA: Transvaal Prov., Nelshoogte galery for. below St., (25°51’S, 30°53′E), 2 xii 1986, coll. Endrödy-Younga #2343, shore washing” (TMSA). Paratypes (50): Same data as holotype (13 TMSA). South Africa: KwaZulu-Natal Province, Umlaas River, marginal vegetation, NAT 173M, (29°44′S, 30°31′E), 6.vii.1973, leg. Unknown (1 AMG); Mpumalanga Province, Kruger National Park, Skukuza, Sabie River, (24°57′S, 30°42′E), 22.ii.1995, leg. Endrödy-Younga (#3110) (36 TMSA). Differential diagnosis. Differentiated from other members of the O. (A.) continentalis Group by the combination of the dorsum of head and the pronotum with very dense, very prominent setae, the hydrofuge pubescence pattern of the abdominal ventrites (described below), and by the aedeagus. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.15/0.56; head width 0.35; pronotum 0.28/0.49; elytra 0.70/0.56. Habitus as illustrated (Fig. 12). Dorsum dark brown to black except hyaline borders of prothorax transparent. Eyes with moderately coarse, convex facets. Frons with deep impressions, borders of impressions rounded. Frons and clypeus densely setose, densely punctate. Labrum anterior margin arcuate in both sexes. Pronotum densely setose, moderately coarsely punctate; anterior and posterior transverse impressions deep, anterior narrowly separated from shallow transverse impression immediately behind anterior margin of lateral lobe; median longitudinal impression moderately deep, narrow, connecting anterior and posterior transverse impressions. Pronotum lateral hyaline borders moderately wide, extended from posterior to anterior angles; sides of non-hyaline part with long conspicuous setae immediately above and resting on hyaline border; anterior and posterior hyaline borders narrow. Elytra wider than non-hyaline part of pronotum, posteriorly rounded, sides arcuate; ten seriate-punctate, punctures moderately large, deep, intervals narrow; each puncture with minute granule at anterior margin, and conspicuous decumbent seta that arches over puncture, attaining base of following seta; lateral margin with row of short, arcuate setae that extend outward from margin in dry specimens. Venter (Fig. 12): Mentum with sparse, moderately large setigerous punctures. Prosternum with very low midlongitudinal carina. Metaventrite tabella large, crown shaped, width ca. 0.6 width of metaventrite, slightly wider than long (ratio ca. 25:20), lateral angles slightly rounded, anterior angle prolonged as distinct carina that attains mesoventral intercoxal process; surface with few very sparse very fine punctures; row of setae along posterior margins very short, other margins without row of setae. Abdominal venter: ventrites 1–2 entirely hydrofuge pubescent; ventrite 3 with hydrofuge pubescence absent in ca. median 1/5; ventrite 4 with hydrofuge pubescence absent in ca. median 1/3; ventrite 5 with hydrofuge pubescence present only narrowly laterally; remaining ventrites glabrous, shining, with sparse setae. Etymology. Named in reference to the densely setose dorsum. Distribution. Currently known from northeastern South Africa (Fig. 26)., Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on pages 521-522, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/7543172

Data from previous literature were used to compile a checklist of the of north African hydraenid beetles. Members of Hydraenidae are mostly 0.5-3 mm in length and genitalia of different species under the same taxonomic group are almost indistinguishable. The external morphology of several taxa, e.g., Ochthebiinae, is largely variable. Mostly all the described genera or subgenera are with uncertain relationships in addition to the presence of many assigned but undescribed species. Here we summarize the recorded species of family Hydraenidae in the north Africa. The species distribution in the Palearctic region is provided. According to the analysis of literature a total of 15, 15, 61, 39 species were recorded in Algeria, Egypt, Morocco, Tunisia respectively. The genus Ochthebius was represented by 15, 13, 36, 16 species, while Hydraena by19, 1, 15, 12 species, and Limnebius species was represented by 3,1, 12, 6 species in Algeria Egypt, Morocco, Tunisia respectively.

Hydraena cameroancylis, new species Figs. 4, 19 (habitus), 19 (aedeagus), 41 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. NW Yaounde, Isali River nr. Nouma, 2.i.1983, leg. P. D. Perkins ” (MCZ). Paratype: Same data as holotype (1 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the anterolateral pronotal foveae large and deep, posterolateral pronotal foveae absent, the brown to dark brown dorsum, and the aedeagus (Fig. 19). Similar in dorsal habitus to H. cameropalmula and H. millenaria; reliable determinations will require examination of the aedeagus. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.35/0.60; head width 0.36; pronotum 0.33/0.48, PA 0.40, PB 0.43; elytra 0.85/0.60. Habitus as illustrated (Fig. 19). Dorsum brown to dark brown, frons and diffusely margined pronotal disc darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately sparcely moderately coarsely punctulate, more sparsely punctulate on pronotal disc than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1–2xef, interstices ca. 1–2xpd or slightly larger; punctures of clypeus very fine, very dense, dull. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal foveae large and deep, posterolateral pronotal foveae absent, posterosubmedial foveae very shallow. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; punctures moderately coarse, on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming moderate angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/2.5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques narrow, short, slightly converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. All tibiae slender, straight. Abdominal apex symmetrical, with apicomedian notch. Distribution. Currently known only from the type locality (Fig. 41). Etymology. Named in reference to the known distribution, and to the strong hook-shaped process of the aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 17-18, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocompacta, new species Figs. 4, 20 (habitus), 20 (aedeagus), 40 (map) Type Material. Holotype (male): “ Cameroon: N. W. Prov., 7 km. E. Bamenda, stream, 30.i.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (12 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the relatively large body size (ca. 1.60 mm), the broad body form, the antero- and posterolateral pronotal foveae moderately deep, shallowly confluent, the wide lateral explanate margins of the elytra, and the aedeagus (Fig. 20). Somewhat similar to H. camerocontinua in body size and form, but differing therefrom in denser dorsal punctation, ventral morphology, and aedeagus. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.59/0.71; head width 0.40; pronotum 0.40/0.55, PA 0.45, PB 0.48; elytra 0.93/0.71. Habitus as illustrated (Fig. 20). Dorsum brown to dark brown or black, frons and diffusely margined pronotal disc darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately sparcely moderately coarsely punctulate, more sparsely punctulate on pronotal disc than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1–2xef, interstices ca. 2–3xpd or slightly larger; punctures of clypeus very fine. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae moderately deep, shallowly confluent, posterosubmedial foveae very shallow. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; punctures moderately coarse, on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/3/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques narrow, very slightly arcuate, converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. Protibia slender, very slightly arcuate. Meso- and metatibiae slender, straight. Abdominal apex asymmetrical, with off-center deep notch. Distribution. Currently known only from the type locality (Fig. 40). Etymology. Named in reference to the known distribution, and to the compact body form., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 18, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameroovala, new species Figs. 1, 10 (habitus), 10 (aedeagus), 41 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. S. Mbalmayo, Nyong River, ex. leaves at margin, 22.v.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (4 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the oval body form, the small body size (ca. 1.18 mm), the posterosubmedial foveae moderately deep, confluent medially forming U-shaped impression, and the aedeagus (Fig. 10). Similar in habitus to some other members of Aedeagal Group 1; reliable determinations will require dissection of males. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.18/0.56; head width 0.34; pronotum 0.31/0.44, PA 0.36, PB 0.39; elytra 0.70/0.56. Habitus as illustrated (Fig. 10). Body form quite oval. Dorsum generally brown to dark brown, maxillary palpi, labrum and clypeus testaceous, pronotum with diffusely margined weakly defined macula. Dorsum of head and pronotum moderately coarsely, often very densely punctulate, frons punctures distinctly finer and less dense than pronotal punctures, interstices shining; punctures of frons disc and pronotal disc ca. 2–3xef, interstices ca. 1xpd or less; punctures of clypeus very fine, very dense, dull. Labrum apicomedially excised, free margins rounded, weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae deep, posterolateral absent, posterosubmedial foveae moderately deep, confluent medially forming U-shaped impression. Elytra with summit of posterior declivity at about posterior 1/3; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect very slightly separately rounded, in posterior aspect margins forming strong angle with one another. Venter: Mentum sparsely finely punctulate, shining; postmentum very finely densely micropunctulate, surrounding areas smooth, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2/3. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques moderately narrow posteriorly, tapering to point anteriorly, slightly converging toward one another anteriorly, weakly raised, located at sides of shallow median depression. AIS width at straight posterior margin ca. 2x P2. All tibiae slender, straight. Abdominal apex asymmetrical, with deep off-center notch. Distribution. Currently known only from the type locality (Fig. 41). Etymology. Named in reference to the known distribution, and to the oval body form., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 11-12, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameroclandestina, new species Figs. 3, 12 (habitus), 12 (aedeagus), 40 (map) Type Material. Holotype (male): “ Cameroon: N. W. Prov., 7 km. E. Bamenda, stream, 30.i.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (5 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the moderately coarsely, very densely punctulate head and pronotum, and the aedeagus (Fig. 12). The dorsal habitus is very similar to that of H. camerocrebrata and H. cameropetila; all three species are in Aedeagal Species Group 2. H.cameroclandestina is larger in body size than H. cameropetila (ca. 1.32 vs. 1.20 mm); also, the P2 is wider than that of the two compared species. Reliable determinations of all three species will require examination of the male genitalia, which distinctly differ from one another. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.32/0.58; head width 0.33; pronotum 0.32/0.47, PA 0.38, PB 0.40; elytra 0.79/0.58. Habitus as illustrated (Fig. 12). Dorsum dark brown to black, pronotum without macula, maxillary palpi brown. Dorsum of head and pronotum moderately coarsely, very densely punctulate, each puncture with short, distinctive whitish seta, interstices dull; punctures of frons disc and pronotal disc ca. 2xef, interstices ca. 1xpd or less; punctures of clypeus fine, dense. Labrum apicomedially excised, free margins rounded, weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral, posterolateral and posterosubmedial foveae shallow. Elytra with summit of posterior declivity at about midlength; lateral explanate margins narrow to moderately wide; on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with short and fine conspicuous whitish seta. Intervals not raised, width ca. 0.5–1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum and postmentum very densely very finely punctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques moderately narrow, parallel, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 2x P2. All tibiae moderately stout. Protibia very slightly arcuate. Meso- and metatibiae straight. Abdominal apex symmetrical, with very small and shallow apicomedian notch. Distribution. Currently known only from the type locality (Fig. 40). Etymology. Named in reference to the known distribution, and to the close dorsal similarity to H. camerocrebrata n. sp. and H. cameropetila n. sp., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 13, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameropalmula, new species Figs. 4, 24 (habitus), 24 (aedeagus), 43 (map) Type Material. Holotype (male): Cameroon: Northwest Province. “ BRITISH CAMEROONS / Matute, / Tiko Plantation / 5.v.1949, B. Malkin ” (UKNHM). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the pronotum with a macula, the absence of posterosubmedial pronotal foveae, and the aedeagus (Fig. 24). Reliable determinations to distinguish this species from other similar members in Aedeagal Species Group 3 will require dissection of males. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.58; head width 0.34; pronotum 0.34/0.47, PA 0.38, PB 0.38; elytra 0.82/0.58. Habitus as illustrated (Fig. 24). Dorsum testaceous to dark brown, head, pronotal macula and elytra dark brown, pronotum rather widely margined in light brown to testaceous, palpi testaceous, tip of last palpomere not darker. Dorsum of head finely sparsely punctulate, pronotum moderately coarsely, densely punctate, punctures much larger than those of frons, interstices shining, ca. 1–2xpd. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae moderately deep, posterolateral foveae very shallow, posterosubmedial foveae absent. Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1xpd or less, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very weak angle with one another. Venter: Mentum and postmentum finely punctulate, shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/4/4. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques narrow, straight, parallel or nearly so, not raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. 2.5x P2. All tibiae slender, protibia very slightly arcuate, meso- and metatibiae straight. Abdominal apex with apicomedian shallow notch in tergite, into which minute apical process of ventrite fits. Distribution. Currently known only from the type locality (Fig. 43). Etymology. Named in reference to the known distribution and the palmate shape of the aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 21, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameroarida, new species Figs. 5, 28 (habitus), 28 (aedeagus), 39 (map) Type Material. Holotype (male): “ Cameroon: N. Prov., 22 km. N. Maroua, desert stream, 14.i.1982, leg. P. D. Perkins ” (MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the brown to dark brown or black dorsum, the deep anterolateral pronotal foveae, and the aedeagus (Fig. 28). Similar in habitus and size to H. camerocontinua, but differing therefrom in denser dorsal punctation, ventral morphology, and aedeagal characters. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.37/0.57; head width 0.34; pronotum 0.32/0.45, PA 0.38, PB 0.40; elytra 0.80/0.57. Habitus as illustrated (Fig. 28). Dorsum brown to dark brown or black, frons and pronotal disc darker, maxillary palpi light brown, tip of last palpomere not darker. Frons finely moderately densely punctulate, ca. 1xef, interstices ca. 1–2xpd, interstices shining. Pronotum moderately coarsely moderately densely punctate, ca. 2xpd of frons punctures; interstices ca. 1xpd or slightly greater, shining. Clypeus medially very finely sparsely punctulate, shining; laterally very finely densely punctulate, dull. Labrum apicomedially excised, free margins not upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal foveae deep, posterolateral shallow, posterosubmedial moderately deep. Elytra with summit of posterior declivity at or very near posterior 1/3; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very weak angle with one another. Venter: Mentum sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques narrow, straight or very slightly arcuate, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. Protibia very slender, straight. All tibiae slender, straight. Abdominal apex symmetrical, with deep apicomedian notch. Distribution. Currently known only from the type locality (Fig. 39). Etymology. Named in reference to the known distribution, and to the arid area., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 23-24, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerosemicordata, new species Figs. 4, 27 (habitus), 27 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: 35 km N. Ngaoundere, stream, 1.v.1982, P. D. Perkins collector” (MCZ). Paratypes: Same data as holotype (6 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the chordate and convex pronotum, the very narrow metaventral plaques, and the aedeagus (Fig. 27). Differentiated from H. camerocarinata n. sp., a species which also has a semichordate pronotum, by the more convex and more chordate pronotum, the deeper pronotal foveae, the area between the antero- and posterolateral pronotal foveae more strongly convex, the more acuminate elytra, and the different proportions of the ventral characters (P2/w/l/s ca. 1/0.2/2/2 vs. 1/0.15/0.15/2). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.37/0.54; head width 0.31; pronotum 0.37/0.44, PA 0.35, PB 0.31; elytra 0.81/0.54. Habitus as illustrated (Fig. 27). Pronotum semicordiform, anterior margin much wider than posterior margin. Dorsum brown except head and pronotal fascia black, palpi light brown to testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately punctulate, more sparsely punctulate on fascia than on surrounding areas, interstices effacedly microreticulate, weakly shining; punctures of frons disc fine and sparse, 1xef or less; punctures of pronotal disc ca. 1–2xef, interstices ca. 1–3xpd; punctures of clypeus fine, moderately dense. Labrum apicomedial excision deep and wide, free margins weakly upturned, angulate laterally and medially. Pronotum distinctly convex, especially transversely, anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae deep, posterosubmedial foveae deep, area between antero- and posterolateral foveae distinctly convex. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures 1–2xpd and deeper than largest pronotal punctures, punctures becoming gradually slightly smaller toward posterior. Intervals not raised, width ca. 1xpd, interstices between punctures of a row ca. 2–3xpd, each puncture with very short and very fine seta. Apices in dorsal aspect conjointly rather sharply rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum and postmentum densely micropunctulate, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.2/2/2. P1 laminate; median carina weakly sinuate in profile. P2 l/w ca. 2.5/1, sides almost parallel, apex blunt. Plaques very small, very narrow, lines, straight, convergent anteriorly, very weakly if at all raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS weakly concave, width at straight posterior margin ca. 2x P2. Pro-, meso- and metatibiae slender, straight. Abdominal apex symmetrical, with apicomedian notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution and the semi-chordate pronotum., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 22-23, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocubita, new species Figs. 3, 15 (habitus), 15 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: 35 km N. Ngaoundere, stream, 1.v.1982, P. D. Perkins collector” (MCZ). Paratypes: 12 km. N. Ngaoundere, lake margin, 1.v.1982, P. D. Perkins collector (2 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the small size (ca. 1.26 mm), the metaventral plaques that are very small, very narrow, subcarinate lines, and the aedeagus (Fig. 15). The dorsal habitus is similar to that of H. cameroconfinis n. sp., but the present species is much smaller (ca. 1.26 vs. 1.66 mm), and has different ventral proportions (P2/w/l/s ca. 1/0.15/0.15/2 vs. 1/0.25/1.5/1). The aedeagi of the two species are markedly dissimilar. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.26/0.52; head width 0.33; pronotum 0.30/0.41, PA 0.33, PB 0.37; elytra 0.76/0.52. Habitus as illustrated (Fig. 15). Dorsum brown to light brown, head and pronotal macula dark brown to black, palpi light brown to testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately densely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of frons disc slightly smaller than 1xef, on pronotal disc slightly larger than 1xef, interstices ca. 2–3xpd or slightly larger; punctures of clypeus obsolete. Labrum apicomedially excised. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae moderately deep, posterolateral pronotal foveae very shallow, posterosubmedial foveae very shallow. Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect slightly separately rounded, in posterior aspect margins forming very shallow angle with one another. Venter: Mentum and postmentum densely micropunctulate, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.15/0.15/2. P1 laminate; median carina weakly sinuate in profile. P2 l/w ca. 2.5/1, sides almost parallel, apex blunt. Plaques very small, very narrow, subcarinate lines, straight, convergent anteriorly, very weakly if at all raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS weakly concave, width at straight posterior margin ca. 2x P2. Pro-, meso- and metatibiae slender, straight. Abdominal apex symmetrical, with apicomedian notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution and the arm-like shape of the gonopore bearing process of the aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 15, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameroconvexa, new species Figs. 5, 32 (habitus), 32 (aedeagus), 41 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. NW Yaounde, Isali River nr. Nouma, 2.i.1983, leg. P. D. Perkins ” (MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the large body size (ca. 1.74 mm, largest known in Cameroon), the pronotum with sides markedly arcuate over middle 1/3, the oval, transversely quite convex elytra, the very wide P1 and P2, the plaques widely separated carinate lines, and the aedeagus (Fig. 32). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.74/0.79; head width 0.42; pronotum 0.42/0.58, PA 0.47, PB 0.48; elytra 1.05/0.79. Habitus as illustrated (Fig. 32). Pronotum with sides markedly arcuate over middle 1/3, sides more strongly sinuate posterior to middle than anterior to middle. Frons finely and moderately sparsely punctulate, punctures ca. 1xef, interstices ca. 1–3xpd, shining. Pronotum coarsely densely punctate in anterior and posterior 1/3, interstices ca. 1xpd, shining; disc convex, very finely very sparsely punctulate, interstices ca. 3–6xpd, shining. Punctures of clypeus very fine, sparse on disc, interstices shining, very dense, dull laterally. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin emarginate over middle 1/2; anterolateral pronotal foveae deep; posterolateral and posterosubmedial pronotal foveae very shallow. Elytra oval, transversely quite convex, posterior declivity abrupt, summit of at or very near midlength; lateral explanate margins wide; punctures coarse, on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, each puncture with very short and very fine seta. Intervals not raised, width ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum finely sparsely punctulate, shining. Postmentum densely micropunctulate, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.2/1/1. P1 and P2 very wide. P2 l/w ca. 1/1, sides parallel, apex blunt. Plaques widely separated carinate lines, located at sides of deep median depression. AIS very wide, width at straight posterior margin ca. 1.2x P2. All tibiae slender. Protibia very slightly arcuate. Meso- and metatibiae straight. Abdominal apex asymmetrical, with deep apicomedian notch. Distribution. Currently known only from the type locality (Fig. 41). Etymology. Named in reference to the known distribution, and to the convex dorsum., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 26, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocontinua, new species Figs. 5, 31 (habitus), 31 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: N. Prov., 35 km N. Ngaoundere, stream, 1.v.1982, leg. P. D. Perkins ” (MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the relatively wide and short P2, l/w ca. 1/1, sides slightly diverging toward apex, apex very indistinct, fused with and at same level as mesoventral intercoxal process., the anterolateral pronotal foveae moderately deep, posterolateral pronotal foveae very shallow or absent, and the aedeagus (Fig. 31). Somewhat similar in habitus to H. cameroarida, but differing in finer, sparser dorsal punctation, ventral characters, and aedeagal morphology. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.47/0.67; head width 0.39; pronotum 0.37/0.52, PA 0.42, PB 0.47; elytra 0.91/0.67. Habitus as illustrated (Fig. 31). Dorsum brown to dark brown or black, frons and diffusely margined pronotal macula darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum sparcely moderately finely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd or slightly larger; punctures of clypeus obsolete. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal foveae moderately deep, posterolateral pronotal foveae very shallow or absent, posterosubmedial foveae very shallow. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; punctures fine, on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very weak angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.3/1/1.3. P1 laminate; median carina sinuate in profile. P2 relatively wide and short, l/w ca. 1/1, sides slightly diverging toward apex, apex very indistinct, fused with and at same level as mesoventral intercoxal process. Plaques narrow, slightly converging toward one another anteriorly, very weakly raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.3x P2. Protibia slender, arcuate. Meso- and metatibiae slender, straight. Abdominal apex symmetrical, with apicomedian notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution, and to the fused intercoxal processes of the meso- and metaventrites., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 25-26, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerodigita, new species Figs. 5, 35 (habitus), 35 (aedeagus), 40, 42 (maps) Type Material. Holotype (male): “ Cameroon: N. Prov., 35 km N. Ngaoundere, stream, 1.v.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (2 MCZ); N. W. Prov., Bamenda, stream nr. Skyline Hotel, 1.ii.1982, leg. P. D. Perkins (4 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the narrow P2 (l/w ca. 4/1), the very small, short and narrow plaques, the deep anterolateral pronotal foveae, and the aedeagus (Fig. 35). Similar in habitus to H. camerosetosa, but differing therefrom in ventral and aedeagal characters. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.25/0.56; head width 0.34; pronotum 0.32/0.43, PA 0.37, PB 0.38; elytra 0.76/0.56. Habitus as illustrated (Fig. 35). Dorsum brown to dark brown, frons and pronotal disc often darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately finely and moderately sparsely punctulate, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–2xpd; clypeus dull, punctures very fine and dense. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal foveae deep, posterolateral and posterosubmedial pronotal foveae moderately deep Elytra with posterior declivity very gradual, summit of at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd or slightly greater, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/ w/l/s) ca. 1/0.5/1/1.5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 4/1, sides parallel, blunt apex raised slightly above mesoventral intercoxal process. Plaques very small, short, narrow, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. All tibiae slender, straight. Abdominal apex symmetrical, with apicomedian notch. Distribution. Currently known only from the type locality and a site at Bamenda (Figs. 40, 42). Etymology. Named in reference to the known distribution, and to the finger-like main-piece of the aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 28, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameroflagellata, new species Figs. 5, 36 (habitus), 36 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. S. Mbalmayo, Nyong River, ex. leaves at margin, 22.v.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (2 MCZ); Akonolinga, moist secondary forest and plantation, at light, 7.i.1978, leg. Gardensforhall & Samuelson (1 LUM). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the small size (ca. 1.05 mm, smallest species in Cameroon), the very narrow, very short, carinate or subcarinate, and widely separated plaques (P2/w/l/s ca. 1/0.2/2/2), and the male genitalia (Fig. 36). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.05/0.45; head width 0.27; pronotum 0.27/0.37, PA 0.31, PB 0.33; elytra 0.77/0.45. Habitus as illustrated (Fig. 36). Dorsum light brown to brown, head, pronotal macula and elytra dark brown, pronotum rather widely margined in light brown to testaceous, palpi testaceous, tip of last palpomere not darker. Dorsum of head finely moderately sparsely punctulate, pronotum moderately finely, moderately densely punctate, punctures ca. 1xpd of largest punctures of frons, interstices shining, ca. 1–3xpd. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae moderately deep, posterolateral shallow or absent, posterosubmedian foveae shallow, medially confluent forming U-shaped impression. Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1xpd or less, as are interstices between punctures of a row.Apices in dorsal aspect separately rounded, in posterior aspect margins forming weak angle with one another. Venter: Mentum moderately sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.2/2/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques very narrow, slightly arcuate, slightly converging toward one another anteriorly, raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. Protibia slender, very weakly arcuate. Meso- metatibiae slender, straight. Abdominal apex symmetrical, with very small apicomedian notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution, and to the very long aedeagal flagellum., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 28-29, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocorona, new species Figs. 1, 8 (habitus), 8 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon, Akonolinga, moist secondary forest and plantation, at light, 7.I.1978, Loc. #17 // Gardenforhall—Samuelson ” (LUM). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the very fine and widely spaced elytral punctures, the comparatively wide lateral explanate margins of the elytra, the pronotal macula, and the aedeagus (Fig. 8). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.26/0.56; head width 0.34; pronotum 0.31/0.4, PA 0.37, PB 0.38; elytra 0.75/0.56. Habitus as illustrated (Fig. 8). Dorsum brown to dark brown or black, frons and diffusely margined pronotal macula darker, frons almost black, contrasting with light brown clypeus, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum sparcely finely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd or slightly larger; punctures of clypeus obsolete. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae moderately deep, shallowly confluent, posterosubmedial foveae very shallow. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; punctures fine, on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 3–4xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very weak angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely punctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.7/4/4. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques moderately wide, slightly converging toward one another anteriorly, weakly raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. 2x P2. Tibiae slender, protibial very slightly arcuate, meso- and metatibiae straight. Abdominal apex symmetrical; last tergite with slightly off-center apical notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution, and the wide lateral explanate margins of the elytra., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 10-11, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerojocula, new species Figs. 1, 9 (habitus), 9 (aedeagus), 41 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. S. Mbalmayo, Nyong River, ex. leaves at margin, 22.v.1982, leg. P. D. Perkins ” (MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the posterosubmedian foveae moderately deep, medially confluent forming U-shaped depression, the metaventral plaques moderately narrow posteriorly, tapering to point anteriorly, and the aedeagus (Fig. 9). Dorsal habitus similar to other species in Aedeagal Group 1; reliable determinations will require examination of the male genitalia. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.35/0.60; head width 0.36; pronotum 0.32/0.46, PA 0.37, PB 0.41; elytra 0.82/0.60. Habitus as illustrated (Fig. 9). Dorsum generally dark brown, except labrum, clypeus and anterolateral angles of pronotum lighter, palpi testaceous, tip of last palpomere not darker. Frons moderately finely and moderately densely punctulate, pronotum moderately coarsely, moderately densely punctate, punctures much larger than those of frons, interstices shining, ca. 1–2xpd. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae deep, posterolateral foveae very shallow, posterosubmedian foveae moderately deep, medially confluent forming U-shaped depression. Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1xpd or slightly greater, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming moderately strong angle with one another. Venter: Mentum sparsely finely punctulate, shining; postmentum very finely densely micropunctulate, surrounding areas smooth, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques moderately narrow posteriorly, tapering to point anteriorly, slightly converging toward one another anteriorly, weakly raised, located at sides of shallow median depression. AIS width at straight posterior margin ca. 2x P2. All tibiae slender, straight. Abdominal apex asymmetrical, with deep off-center notch. Distribution. Currently known only from the type locality (Fig. 41). Etymology. Named in reference to the known distribution, and to the smile shaped pronotal fovea., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 11, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Thirty-three new species of Cameroonian water beetles in the genus Hydraena Kugelann are described, based on the examination and databasing of 355 specimens from 19 localities/events. Male genitalia are illustrated, and high resolution habitus images of the holotypes are provided, as are distribution maps. The following new species of Hydraena are described: H. cameroancylis, H. cameroarida, H. camerobuloba, H. camerocameola, H. camerocarinata, H. cameroclandestina, H. camerocompacta, H. camerocomplexa, H. camerocompressa, H. cameroconcava, H. cameroconfinis, H. camerocontinua, H. camerocontrasta, H. cameroconvexa, H. camerocordata, H. camerocorona, H. camerocrebrata, H. camerocubita, H. camerocurvata, H. camerodidacta, H. camerodigita, H. cameroflagellata, H. camerofoveata, H. camerojocula, H. camerolatula, H. cameroovala, H. cameropalmula, H. cameropetila, H. cameroradiata, H. camerosemicordata, H. camerosetosa, H. camerosicula, and H. millenaria.

Hydraena camerocurvata, new species Figs. 3, 16 (habitus), 16 (aedeagus), 40 (map) Type Material. Holotype (male): “ Cameroon: N. W. Prov., 7 km. E. Bamenda, stream, 30.i.1982, leg. P. D. Perkins ” (MCZ). Paratype: Same data as holotype (1 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the ovate body form, the transversely convex pronotum, the posterosubmedial foveae shallow, confluent medially forming U-shaped impression, the very narrow P2, and the aedeagus (Fig. 16). Differentiation from other similarly shaped members of Aedeagal Species Group 2 will require careful examination of the aedeagus. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.30/0.57; head width 0.34; pronotum 0.31/0.49, PA 0.39, PB 0.41; elytra 0.80/0.57. Habitus as illustrated (Fig. 16). Body form ovate. Dorsum generally brown to dark brown, maxillary palpi, labrum and clypeus testaceous, pronotum with diffusely margined weakly defined macula. Dorsum of head and pronotum moderately coarsely, moderately densely punctulate, frons punctures distinctly finer and less dense than pronotal punctures, interstices shining; punctures of frons disc and pronotal disc ca. 1–2xef, interstices ca. 1–2xpd; punctures of clypeus fine, moderately dense, interstices shining medially, dull laterally. Labrum apicomedially excised, free margins rounded, weakly upturned. Pronotum transversely convex, anterior margin weakly emarginate over middle 1/2; anterolateral and posterolateral foveae shallow, posterosubmedial foveae shallow, confluent medially forming U-shaped impression, anteromedial fovea moderately deep. Elytra with summit of posterior declivity at about posterior 1/3; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum and postmentum sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/3/3. P1 laminate; median carina sinuate in profile. P2 very narrow, l/w ca. 4/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques narrow, very slightly arcuate, tapering anteriorly and slightly converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 3x P2. All tibiae stout. Protibia widened near midlength, very slightly arcuate. Meso- and metatibiae straight. Abdominal apex symmetrical, last tergite rounded, without apicomedian notch, last ventrite emarginate. Distribution. Currently known only from the type locality (Fig. 40). Etymology. Named in reference to the known distribution, and to the ovate body form and very curvaceous aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 15-16, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocrebrata, new species Figs. 3, 14 (habitus), 14 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: Yaounde: Mt. Febe, 950 m., hygropetric, 10.iv.1982, P. D. Perkins collector” (MCZ). Paratypes (120): Same data as holotype (28 MCZ); same data except 7.iv.1982 (5 MCZ); same data except 18.vi.1983 (64 MCZ); same data except 14.vi.1983 (12 MCZ); Yaounde, Mt. Mbankolo, 900m, hygropetric microhabitat, 20.v.1982, P. D. Perkins collector (11 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the very densely punctate dorsum, the very narrow P2 (l/w ca. 4/1) and the aedeagus (Fig. 14). Also refer to the diagnosis of H. camerocompressa. Although the aedeagi of H. camerocrebrata and H. cameropetila distinctly differ in several characters, a relationship of the two species is indicated by the shapes of the parameres: large, wide and with similar clusters of setae (Figs. 14, 18). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.57; head width 0.31; pronotum 0.33/0.48, PA 0.41, PB 0.42; elytra 0.85/0.57. Habitus as illustrated (Fig. 14). Dorsum dark brown to black, pronotum without macula, palpi brown. Dorsum of head and pronotum moderately coarsely, very densely punctulate, each puncture with short, distinctive whitish seta, interstices dull; punctures of frons disc and pronotal disc ca. 2–3xef, interstices ca. 1xpd or less; punctures of clypeus fine, dense. Labrum apicomedially excised, free margins rounded, weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral, posterolateral and posterosubmedial foveae moderately deep. Elytra with summit of rather abrupt posterior declivity at about posterior 1/3; lateral explanate margins narrow to moderately wide; on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 0.5xpd or less, as are interstices between punctures of a row. Apices in dorsal aspect very slightly separately rounded, in posterior aspect margins forming very weak angle with one another. Venter: Mentum and postmentum nitid, dull. Genae very slightly raised, very weakly shining, with posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/6/6. P1 laminate; median carina weakly sinuate in profile. P2 very narrow, l/w ca. 4/1, sides parallel, apex blunt. Plaques narrow, straight or very slightly arcuate, slightly convergent anteriorly, weakly raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS weakly concave, width at arcuate posterior margin ca. 2.5x P2. Pro- meso- and metatibiae straight, moderately stout.Abdominal apex symmetrical, without apicomedian notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution and to the very densely punctate dorsum., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 14-15, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocomplexa, new species Figs. 3, 13 (habitus), 13 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: Yaounde: Mt. Febe, 950 m., hygropetric, 10.iv.1982, P. D. Perkins collector” (MCZ). Paratype: Same data as holotype (1 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the small size (ca. 1.16 mm), the relatively large and wide pronotum (length/width ratio ca. 17/25), the moderately deep pronotal foveae, and the aedeagus (Fig. 13). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.16/0.54; head width 0.33; pronotum 0.31/0.46, PA 0.39, PB 0.41; elytra 0.81/0.54. Habitus as illustrated (Fig. 13). Dorsum light brown, head and pronotal macula darker (holotype is teneral), palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum densely moderately finely punctulate, interstices weakly shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–2xpd; punctures of clypeus very fine and dense. Labrum apicomedially excised, free margins rounded, weakly upturned. Pronotum relatively large and wide, length/width ratio ca. 17/25. Pronotum with anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae shallow, posterosubmedial foveae moderately deep. Elytra with posterior declivity very gradual, summit slightly beyond midlength; lateral explanate margins moderately wide; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1xpd or less, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very weak angle with one another. Venter: Mentum and postmentum finely sparsely punctulate, weakly shining. Genae very slightly raised, shining, with weak posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/2. P1 laminate; median carina weakly sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt. Plaques moderately narrow, straight, slightly convergent anteriorly, weakly raised, located at sides of moderately deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS weakly concave, width at straight posterior margin ca. 1.5x P2. Pro- meso- and metatibiae moderately stout, straight. Abdominal apex symmetrical, without apicomedian notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution and the very complex aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 13-14, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocordata, new species Figs. 5, 33 (habitus), 33 (aedeagus), 41 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., Etoug Ebe, stream with dead leaves, 22.iv.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (2 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the large body size (ca. 1.53 mm), the markedly cordiform pronotum, the very wide P1 and P2, and the aedeagus (Fig. 33). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.53/0.69; head width 0.36; pronotum 0.38/0.52, PA 0.41, PB 0.38; elytra 0.90/0.69. Habitus as illustrated (Fig. 33). Pronotum markedly cordiform, width at midlength much wider than anterior and posterior margins. Dorsum dark brown to black, except labrum, clypeus, and maxillary palpi light brown to testaceous, tip of last palpomere not darker. Frons moderately finely moderately sparsely punctate, punctures ca. 1xef. Pronotum coarsely densely punctate, especially anterior and posterior to moderately convex disc, interstices in densely punctate areas narrow walls; interstices on disc ca. 1xpd, shining; punctures laterally much smaller and sparser. Punctures of clypeus very fine, moderately dense on disc, very dense laterally. Labrum apicomedian excision deep and wide, free margins weakly upturned, angulate laterally and medially. Pronotum anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae deep, shallowly confluent; posterosubmedial foveae deep, area between antero- and posterolateral foveae distinctly convex. Elytra with posterior declivity rather abrupt, summit at or very near midlength; lateral explanate margins wide; on basal 1/3 punctures 1xpd or slightly larger and deeper than largest pronotal punctures, punctures becoming gradually slightly smaller laterally and toward posterior. Intervals not raised, width on disc ca. 1xpd, much wider laterally and posteriorly, interstices between punctures of a row ca. 1–6xpd, each puncture with very short and very fine seta. Apices in dorsal aspect conjointly rather sharply rounded, in posterior aspect margins forming shallow angle with one another. Venter: Mentum finely sparsely punctulate, shining. Postmentum densely micropunctulate, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.1/0.2/1.5. P1 and P2 very wide. P2 l/w ca. 1/1, sides parallel, apex blunt. Plaques very small, very short, widely separated carinate lines, located at sides of deep median depression. AIS very wide, weakly concave, width at straight posterior margin ca. 1.2x P2. Tibiae slender, straight. Protibia very slightly widened and bearing short spine at ca. distal 2/3. Mesotibia slightly widened at ca. distal 2/3. Abdominal apex symmetrical, with rather wide and deep apicomedian notch. Distribution. Currently known only from the type locality (Fig. 41). Etymology. Named in reference to the known distribution, and to the markedly cordiform pronotum., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 26-27, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena cameroradiata, new species Figs. 5, 37 (habitus), 37 (aedeagus), 41 (map) Type Material. Holotype (male): “ Cameroon: C. S. Prov., Yaounde: Bastos, puddle, 12.xii.1981, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (10 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the very sparcely and very finely punctulate head and pronotum, interstices strongly shining, the anterolateral pronotal foveae moderately deep, posterolateral and posterosubmedial foveae absent, the absence of metaventral plaques, and the aedeagus (Fig. 37). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.59; head width 0.34; pronotum 0.35/0.47, PA 0.38, PB 0.43; elytra 0.80/0.59. Habitus as illustrated (Fig. 37). Dorsum brown to light brown, frons and diffusely margined pronotal macula slightly darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum sparcely finely punctulate, pronotum more finely sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of pronotal disc ca. 1xef, interstices ca. 3–5xpd or slightly larger; punctures of frons disc slightly larger and more closely spaced than those of pronotal disc; punctures of clypeus very fine, nearly obsolete. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal foveae moderately deep, posterolateral and posterosubmedial foveae absent. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins narrow; punctures fine, on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 2–4xpd, as are interstices between punctures of a row. Apices in dorsal aspect separately rounded, in posterior aspect margins forming moderately strong angle with one another. Venter: Mentum and postmentum sparsely finely punctulate, shining. Genae raised, shining, without posterior ridge. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques absent, median depression deep. AIS width at straight posterior margin ca. 2x P2. All tibiae slender. Pro- and mesotibiae very slightly arcuate, metatibia straight. Abdominal apex symmetrical, with shallow apicomedian notch. Distribution. Currently known only from the type locality (Fig. 41). Etymology. Named in reference to the known distribution, and to the highly reflective dorsum., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on page 29, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerodidacta, new species Figs. 5, 34 (habitus), 34 (aedeagus), 40 (map) Type Material. Holotype (male): “ Cameroon: N. W. Prov., 7 km. E. Bamenda, stream, 30.i.1982, leg. P. D. Perkins ” (MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the comparatively large body size (ca. 1.65 mm), the finely sparsely punctulate frons and pronotum, punctures very consistent in size throughout, interstices shining, the anterolateral foveae moderately deep, posterolateral and posterosubmedian foveae very shallow or absent, the very narrow plaques, with margins very ill-defined, and the aedeagus (Fig. 34). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.65/0.69; head width 0.38; pronotum 0.38/0.53, PA 0.42, PB 0.48; elytra 0.98/0.69. Habitus as illustrated (Fig. 34). Dorsum brown to dark brown, head, pronotal fascia and elytra dark brown, pronotum rather widely bordered anteriorly and posteriorly in light brown, maxillary palpi testaceous, tip of last palpomere not darker. Frons and pronotum finely sparsely punctulate, punctures of pronotum slightly larger than those of frons, very consistent in size throughout, interstices shining, ca. 1–3xpd. Clypeus medially very finely sparsely punctulate, shining; laterally densely micropunctulate, dull. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae moderately deep, posterolateral and posterosubmedian foveae very shallow or absent. Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals shining, not raised, width ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect rather sharply conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely very densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.3/1.3/1.3. P1 laminate; median carina sinuate in profile. P2 moderately wide, l/w ca. 2/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques very narrow, margins very ill-defined, slightly arcuate, slightly converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1x P2.All tibiae slender. Protibia and mesotibia very weakly arcuate. Metatibia straight. Abdominal apex symmetrical, with deep, narrow apicomedian notch. Distribution. Currently known only from the type locality (Fig. 40). Etymology. Named in reference to the known distribution, and to the two finger-like processes of the aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 27-28, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerosicula, new species Figs. 1, 11 (habitus), 11 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: N. Prov., 35 km N. Ngaoundere, stream, 1.v.1982, leg. P. D. Perkins ” (MCZ). Paratypes: Same data as holotype (3 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the comparatively large body size (ca. 1.49 mm), the deep pronotal impressions, the comparatively wide P2, the narrow median depression between the metaventral plaques, and the aedeagus (Fig. 11). Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.49/0.69; head width 0.39; pronotum 0.37/0.51, PA 0.41, PB 0.46; elytra 0.93/0.69. Habitus as illustrated (Fig. 11). Dorsum brown to dark brown, frons and pronotal macula darker, maxillary palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately finely moderately sparsely punctulate, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd; clypeus dull, punctures very fine and dense. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae deep, confluent with shallow posterolateral; posterosubmedial pronotal foveae moderately deep, markedly punctate. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd or less, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/1. P1 laminate; median carina sinuate in profile. P2 comparatively wide, l/w ca. 2/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques moderately narrow, slightly arcuate, parallel, tapering anteriorly, weakly raised, located at sides of moderately deep, narrow median depression. AIS width at straight posterior margin ca. 1.5x P2. Protibia very slender, straight. All tibiae slender, straight. Abdominal apex asymmetrical, with deep off-center notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution, and to the dagger-shaped process of the aedeagus., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 12-13, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841

Hydraena camerocompressa, new species Figs. 4, 21 (habitus), 21 (aedeagus), 42 (map) Type Material. Holotype (male): “ Cameroon: 35 km N. Ngaoundere, stream, 1.v.1982, P. D. Perkins collector” (MCZ). Paratypes: Same data as holotype (6 MCZ). Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the very narrow P2 (l/w ca. 4/1), the unusual ratios of P2 width and plaque shape (P2/w/l/s ca. 1/1/6/5), and the aedeagus (Fig. 21). Although the P2 is very narrow, as is that of H. camerocrebrata n. sp., the habitus and aedeagi of the two species markedly differ. H. cameropetila (CAM13) also has a very narrow P2, but lacks metaventral plaques. Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.40/0.61; head width 0.33; pronotum 0.33/0.48, PA 0.37, PB 0.39; elytra 0.83/0.61. Habitus as illustrated (Fig. 21). Dorsum brown to light brown, head and pronotal macula darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately densely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd or slightly larger; punctures of clypeus obsolete. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae shallow, posterosubmedial foveae very shallow. Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd or less, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Venter: Mentum and postmentum nitid, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/6/5. P1 laminate; median carina weakly sinuate in profile. P2 narrow, l/ w ca. 4/1, sides parallel, apex blunt. Plaques narrow, straight, parallel, weakly raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS weakly concave, width at straight posterior margin ca. 1.5x P2. Pro- meso- and metatibiae slender, straight. Abdominal apex with deep asymmetrical slightly off-center notch. Distribution. Currently known only from the type locality (Fig. 42). Etymology. Named in reference to the known distribution and the very narrow mesoventral intercoxal process (P2)., Published as part of Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), pp. 1-66 in Zootaxa 5203 (1) on pages 18-19, DOI: 10.11646/zootaxa.5203.1.1, http://zenodo.org/record/7284841