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Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima, Sinha, Bikramjit (2022): Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya. Zootaxa 5196 (4): 511-534, DOI: https://doi.org/10.11646/zootaxa.5196.4.3

Larval key to the known species of Indian Tenuibaetis Kang & Yang, 1994 1. Posterior margin of terga IV with spines apically rounded..................................................... 2 - Posterior margin of terga IV with spines apically pointed..................................................... 3 2. Dorsal margin of femur with a row of 16–17 long simple setae.................................... T. himani sp. nov. - Dorsal margin of femur with a row of 23–25 long and blunt setae................................... T. kangi sp. nov. 3. Labrum with U-shaped marking medially; tracheae of gills distinct.................................... T. inornatus - Labrum without U-shaped marking medially; tracheae of gills absent............................................ 4 4. Dorsal margin of tibia with spatulate setae and tarsi short spine-like setae; paraproct with about 20 marginal spines; length of caudal filament vs. cerci ratio 0.6×.............................................................. T. frequentus - Dorsal margin of tibia and tarsi with only thin setae; paraproct with about 14 marginal spines; length of caudal filament vs. cerci ratio 0.75×.................................................................................... T. arduus, Published as part of Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima & Sinha, Bikramjit, 2022, Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya, pp. 511-534 in Zootaxa 5196 (4) on page 530, DOI: 10.11646/zootaxa.5196.4.3, http://zenodo.org/record/7235702, {"references":["Kang, S. - C., Chang, H. - C. & Yang, C. - T. (1994) A revision of the genus Baetis in Taiwan. Journal of Taiwan Museum, 47, 9 - 44."]}

Tenuibaetis himani Kubendran, Vasanth & Subramanian sp. nov. (Figs 1A–B, 2A–I, 3A–I) Material examined. Holotype. Larva, INDIA, Himachal Pradesh, Kinnaur district, Baspa River, Sangla Valley, 31°25′09″ N 78°16′07″ E, Alt. 2600 m. 27.IX.2017, Coll. T. Kubendran (Reg. No. HARC /I-6190). Paratypes. 3 larvae, same data as holotype (Reg. No. HARC /I-6191). Description. Mature larva (Figs 1A–B). Body length: 4.2–4.4 mm; cerci length 2.5–3.0 mm; paracercus length 1.5 mm; antenna 1.2× as long as head capsule length. Coloration. Head uniformly brown with a pair of medially pale white; brown with light yellow transverse band on the posterior half of mesonotum; base of clypeus pale yellow (Fig. 1A); dark or light brown tergal color pattern typical of the genus, with a pale-yellow transverse band on the posterior half of mesonotum; two paired pale-yellow maculae on abdominal terga IV–V and terga IX–X pale yellow; cerci light brown without a brown band at ca. ½ of cerci; thorax and abdomen ventrally brownish white, brighter than dorsally; legs light brown; femur dorsally pale and light brown apically, distomedially brown; claws distally brownish. Morphology. Antenna (Fig. 3C). Scape and pedicel sub-cylindrical, flagellum with thin and simple setae on apex of each segment. Labrum (Fig. 2A). Subrectangular with length 0.7× maximum width. Medial emargination of distal margin with a small, apically pointed process. Dorsally with many medium, fine, simple setae; submarginal arc of setae composed of 1+4 simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with two short, spine-like setae near lateral and anterolateral margin. Right mandible (Figs 2B, C). Incisors fused. Outer and inner sets of denticles with 3+3 denticles each. Prostheca slender, distolaterally denticulate. Margin between prostheca and mola without tubercle. Tuft of setae at apex of mola present. Left mandible (Figs 2D, E). Incisors fused. Outer and inner sets of denticles with 3+4 denticles each. Prostheca robust, apically with small denticles and comb-shape structure. Margin between prostheca and mola straight. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically constricted. Tuft of setae at apex of mola present. Both mandibles with lateral margins almost straight; basal half with fine, simple setae scattered over dorsal surface. Hypopharynx (Fig. 2F). Lingua approx. as long superlingua. Lingua longer than broad, distal half not expanded. Superlingua rounded, lateral margin rounded with thin setae along distal margin. Maxilla (Figs 2G, H). Maxilla apically with three canines and three dentisetae, lacinia with two rows of setae, one row with abundant thin setae ending with stout and long setae, second row with fine, long stout setae. Inner dorsal row of setae with three dentisetae, distal dentiseta tooth-like; middle dentiseta slender, bifid and serrate; proximal dentiseta slender, biserrate and with proximal furcation strongly developed and abducted. Medially with one feathered spine-like seta and 4–5 long, simple setae. Maxillary palp slightly longer than galea–lacinia; two segmented. Segment I equal in length to segment II. Apex of segment II rounded without nipple and without excavation at inner distolateral margin. Setae on maxillary palp fine and simple over surface of segments. Labium (Fig. 2I). Glossa shorter than paraglossa; inner margin with 6 spine-like setae. Most apical setae much longer than other setae; apex with one long, robust, spatulate setae and one medium, robust seta; outer margin with 4–5 spine-like setae, base with simple setae. Paraglossa subrectangular slightly curved inward; apex rounded with three rows of long robust distally pectinate setae in apical area and few simple setae in antero-medial area. Dorsally with a row of long spine-like setae near inner margin. Labial palp 3-segmented; segment I shorter than segments II and III combined. Segment II slightly produced inward to form a moderately expanded lobe at distal corner; dorsally with a row of fine medium simple setae; segment III conical, slightly asymmetrical with a small concavity at inner apex; covered with short stout spine-like setae. Segments II and III with fine simple setae scattered over dorsal surface. Hind wing pads (Fig. 3D). Present, well developed. Foreleg (Fig. 3F). Ratio of foreleg segments 1.1:1.0:0.5:0.2. Femur length ca. 3× maximum width. Dorsal margin with a row of ca 16–17 long, stout, apically rounded setae; length of setae 0.25× maximum width of femur. Apex rounded with a row of short, stout, pointed setae, many stouts lanceolate setae on lateral surface. Villopore well developed. Dorsal margin of tibia with a row of fine simple setae, stout setae absent; ventral margin with a row of 6–7 spine-like setae and a tuft of long, fine, simple setae; anterior surface scattered with stout, short, spatulate setae. Dorsal margin of tarsus with hair–like setae; ventral margin with 9–10 stout setae increasing in length towards apex. Claw (Fig. 3G) with a row of 11 denticles; distally pointed, 6–7 stripes, subapical setae absent. Terga (Fig. 3A–B). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae, with stripes and tergum IX irregular spines apically. Gills (Fig. 3H, I). Single lamellate gills present on segments I–VII. Margin with small denticles intercalating fine, simple setae. Abdominal gills I, II, VI and VII without visible trachea and III–V with poorly visible trachea. Tracheae limited to proximal part of main trunk. Paraproct (Fig. 3E). Distally not expanded, with 12–13 marginal stout spines. Surface scattered with micropores and fine simple setae, and with a patch of notched scales. Cercotractor with medium, marginal spines. Imago. Unknown. Etymology. The new species is named after the type locality located near snow (Himani meaning snow in Hindi), in the state of Himachal Pradesh, India. Distribution. North Western Himalaya (Himachal Pradesh), India. Diagnosis. Larva. Tenuibaetis himani Kubendran, Vasanth & Subramanian sp. nov. can be distinguished from all known species of Tenuibaetis by the following combination of characters: (i) dark and light brown tergal colour pattern typical of the genus with a pale yellow transverse band on the posterior half of mesonotum, two paired pale yellow maculae on abdominal terga IV–V and terga IX–X pale yellow (Figs 1A–B); (ii) labrum dorsal submarginal arc of setae composed of one plus four simple setae (Fig. 2A); (iii) right mandible: canine with 3+3 denticles, prostheca slender, apically denticulate (Figs 2B–C); (iv) left mandible: canine with 3+4 denticles (Fig. 2D); (v) maxilla: distal dentiseta slender, trifid and pectinate; middle dentiseta slender, bifid and serrate; proximal dentiseta slender, biserrate and with proximal furcation strongly developed and abducted (Fig. 2H); (vi) labial palp segment II slightly produced inward to form a moderately expanded lobe at distal corner, segment III conical, slightly asymmetrical with a small concavity at inner apex (Fig. 2I); (vii) fore femur dorsal margin with 16–17 long, stout, apically rounded setae, anterior surface with a row of robust setae with median spine-like setae (Fig. 3F); (viii) claw with a row of 11 denticles, subapical seta absent (Fig. 3G); (ix) abdominal gills I, II, VI and VII without trachea and III–V with poorly developed trachea (Figs 3H, I); (x) paraproct distally not expanded, 12–13 marginal spines, surface with a patch of notched scales (Fig. 3E). Habitat. Tenuibaetis himani sp. nov. was collected in Baspa River (Fig. 14A) (from 3.5–5 m wide and 16–17 cm depth), Sangla Valley. This river is characterized by medium temperature 15–18 ° C and relative humidity 30–33% at the time of sampling, average current velocity (0.5 m /sec) and mainly gravel and pebbles at the bottom of river., Published as part of Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima & Sinha, Bikramjit, 2022, Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya, pp. 511-534 in Zootaxa 5196 (4) on pages 512-514, DOI: 10.11646/zootaxa.5196.4.3, http://zenodo.org/record/7235702

Tenuibaetis inornatus (Kang & Yang, 1994) (Figs 10A–B, 11A–F, 12A–G) Baetis (Tenuibaetis) inornatus in Kang et al. n. sp. 1994: 28 Baetiella inornata Waltz & McCafferty, 1997: 136 n. comb. Tenuibaetis inornatus Fujitani, Hirowatari and Tanida 2003a: 127 n. comb. Material examined. 1 larva, INDIA, Arunachal Pradesh, West Kameng district, Chakparang stream, Dirang Valley, 27°25′20″ N, 92°17′17″ E, 13.III.2018, Coll. Bikramjit Sinha (Reg. No. I /E/540). Description. Mature larva (Figs 10A–B). Body length 5.2 mm; cerci length 2.3 mm; paracercus length 1.2 mm; antenna 1.0× as long as head capsule length. Coloration (Figs 10A–B). Head dark brown, medially pale white with a pair of dark spots; base of clypeus pale yellow (Fig. 10B). Thorax brown with bright medially, dorsal suture, mesothorax medially with bright yellowish and abdomen dorsally dark brown with two dark spots medial areas (Fig. 10A); abdominal segment IX–X pale white. Head, thorax and abdomen ventrally brownish white, somewhat brighter than dorsally. Legs light brown; femur dorsally pale and apical margin dark brown, distomedially dark brown; claws distally dark brown; caudal filaments brownish yellow. Morphology. Antenna (Fig. 10B). Scape and pedicel sub-cylindrical, flagellum with rounded spines apically and fine, simple setae on apex of segments. Labrum (Figs 11A–B). Rectangular with length 0.8× maximum width. Medial emargination of distal margin with a small, apically pointed process. Dorsally with many medium, fine, simple setae; submarginal arc of setae composed of 1+5 simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with two short, spine-like setae near lateral and anterolateral margin. Right mandible (Fig. 11D). Incisors fused. Outer and inner sets of denticles with 4+4 denticles respectively. Prostheca stick-like, apically and distolaterally denticulate. Margin between prostheca and mola straight. Tuft of setae at apex of mola present. Left mandible. Incisors fused. Outer and inner sets of denticles with 4+4 denticles respectively, plus one-minute, intermediate denticle. Prostheca robust, apically with small denticles and comb–shape structure. Margin straight between prostheca and mola. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically constricted. Tuft of setae at apex of mola present. Both mandibles with lateral margins almost straight; basal half with fine, simple setae scattered over dorsal surface. Hypopharynx (Fig. 11C). Lingua about as long as superlingua; lingua longer than wide; apically triangular with medial tuft of hair-like setae; distal half not expanded. Superlingua with distal margin straight; lateral margins angulated; fine, long, simple setae along distal margin; short, pointed setae along lateral margin. Maxilla (Fig. 11E). Galea-lacinia with two simple, robust apical setae under crown. Inner dorsal row of setae with three dentisetae, distal dentiseta tooth-like; middle dentiseta slender, biserrate and proximal dentiseta furcation strongly developed and abducted. Medially with one feathered spine-like seta and 4–5 long, simple setae. Maxillary palp 1.2× as long as length of galea-lacinia; two segmented. Segment II 1.2× longer than segment I. Apex of segment II rounded without nipple. Setae on maxillary palp fine and simple setae over surface of segments I and II. Labium (Fig. 11F). Base of glossa broad, towards narrowing apex; paraglossa shorter; inner margin with 10–11 spine-like setae increasing the length of distally; apex with three long and one medium, robust, pectinate setae; outer margin with 5–6 spine-like setae increasing in length distally, base with small medium, simple setae. Paraglossa subrectangular slightly curved inward; apex rounded, with three rows of long, simple, robust, pectinate setae in apical area and 4 medium, simple setae in antero-medial area. Dorsally with a row of five long spine-like setae near inner margin. Labial palp 3-segmented; segment I 0.9× length of segments II and III combined. Segment II only slightly produced distolaterally; inner and outer margin with short and simple setae; dorsally with a row of spinelike medium simple setae; segment III conical, slightly pointed apically; covered with short, stout, spine-like setae. Segments I, II and III with fine simple setae scattered over dorsal surface. Hind wing pads. Present, well developed. Foreleg (Fig. 12A). Ratio of foreleg segments 1.4:1.0:0.7:0.3. Femur. Length ca. 3× maximum width; dorsal margin with a row of ca 20–21 long, curved, apically rounded setae; length of setae 0.25x maximum width of femur; apex rounded with a row 4–5 short, stout, pointed setae, many stout lanceolate along ventral margin; villopore well developed. Tibia. Dorsal margin with a row of short, stout, pointed setae, fine, simple setae; ventral margin with a row of short, spine-like setae, on apex one stout pointed, simple setae; anterior surface with scattered stout setae, lanceolate; tibio-patellar suture present on basal 2/3 area. Tarsus. Dorsal margin with a row of short, stout setae; ventral margin with a row of spine-like setae. Claw distally pointed and curved with one row of 12–13 denticles (Fig. 12C). Terga (Figs 10A–B). Surface with scattered V-shaped scale bases and scattered fine, simple setae. Posterior spines of abdominal terga blunt, abdominal terga of each segment with a pair of small spots; tergum IX–X pale yellow. Gills (Figs 12D–F). Single lamellate gills present on segments I–VII. Margin with small serration, simple setae. Gill I small; tracheae distinct. Paraproct (Fig. 12G). Distally not expanded, with 11 marginal stout spines. Surface with V-shaped scale bases, microspores fine and simple, with a patch of scales. Cercotractor with medium, marginal spines. Diagnosis: Tenuibaetis inornatus can be distinguished by the following combination of characters: (i) labrum deeply cleft with “V” shaped mark medially (Figs 11A–B); (ii) spines at posterior margin of abdominal terga blunt (Fig. 10A); (iii) gill I longer (Fig. 12D); (iv) claw with 12 denticles (Fig. 12C). Distribution: Taiwan and India (Arunachal Pradesh). Remarks: This species was originally described from Taiwan based on larvae (Kang & Yang 1994). Presently, the new record of the larvae Tenuibaetis inornatus from Arunachal Pradesh is an extension of its species distributional range., Published as part of Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima & Sinha, Bikramjit, 2022, Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya, pp. 511-534 in Zootaxa 5196 (4) on pages 526-529, DOI: 10.11646/zootaxa.5196.4.3, http://zenodo.org/record/7235702, {"references":["Kang, S. - C., Chang, H. - C. & Yang, C. - T. (1994) A revision of the genus Baetis in Taiwan. Journal of Taiwan Museum, 47, 9 - 44.","Waltz, R. D. & McCafferty, W. P. (1997) New generic synonymies in Baetidae (Ephemeroptera). Entomological News, 108, 134 - 140.","Fujitani, T., Hirowatari T. & Tanida, K. (2003 a) Genera and species of Baetidae in Japan: Nigrobaetis, Alainites, Labiobaetis, and Tenuibaetis n. stat. (Ephemeroptera). Limnology 4, 121 - 129. https: // doi. org / 10.1007 / s 10201 - 003 - 0105 - 2"]}

Tenuibaetis kangi Kubendran, Vasanth & Subramanian sp. nov. (Figs 1C, 4A–G, 5A–H, 6A–E) Material examined. Holotype. Mature larva, INDIA, Himachal Pradesh, Kangra district, Baijnath, tributary of Beas River, 32°01′27″ N, 76°23′28″ E, 13.XI.2019, Alt. 998 m. Coll. T. Kubendran and Fatima Jabeen (Reg. No. HARC /I-7626). Paratypes. 1 male and 1 female imago reared from larvae, 18 larvae same data as holotype (Reg. No. HARC /I-7645). Description. Mature larva (Fig. 1C). Body length 5.3–5.8 mm; cerci length 2.8–3.2 mm; paracercus length 1.8–2.2 mm; antenna 1.5× as long as head capsule length. Coloration. Head uniformly brown, medially pale white; brown with light yellow transverse band on the posterior half of mesonotum as in (Fig. 1C). Dark or light brown tergal color pattern typical of the genus, with a pale-yellow transverse band on the posterior half of mesonotum, two paired pale-yellow maculae on abdominal terga IV–V and terga IX–X pale yellow, cerci light brown without a brown band at ca. ½ of cerci. Thorax and abdomen ventrally brownish white, brighter than dorsally. Legs light brown; femur dorsally pale and light brown apically, distomedially brown; claws distally brownish. Morphology. Antenna (Fig. 4G). Scape and pedicel sub-cylindrical, flagellum with thin and simple setae on apex of each segment. Labrum (Fig. 4A). Subrectangular with length 0.7× maximum width. Medial emargination of distal margin with a small, apically pointed process. Dorsally with many medium, fine, simple setae; submarginal arc of setae composed of 1+3 simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with three short, spine-like setae near lateral and anterolateral margin. Right mandible (Fig. 4C). Incisors fused. Outer and inner sets of denticles with 3+3 denticles each. Prostheca slender, distolaterally denticulate. Margin between prostheca and mola without tubercle. Tuft of setae at apex of mola present. Left mandible (Fig. 4D). Incisors fused. Outer and inner sets of denticles with 3+3 denticles each. Prostheca robust, apically with small denticles and comb–shape structure. Margin between prostheca and mola straight. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically constricted. Tuft of setae at apex of mola present. Both mandibles with lateral margins almost straight; basal half with fine, simple setae scattered over dorsal surface. Hypopharynx (Fig. 4B). Lingua as long as superlingua. Lingua about as broad as long covered with short, thin setae, distal half not expanded. Superlingua rounded, lateral margin rounded with thin, setae along distal margin and short, pointed setae along lateral margin. Maxilla (Fig. 4E). Galea-lacinia with two simple, robust apical setae under crown; apically with three canines, lacinia with two rows of setae, one row with abundant thin setae ending with stout and long setae, second row with fine, long stout setae. Inner dorsal row of setae with three dentisetae, distal dentiseta tooth-like; middle dentiseta slender and bifid; proximal dentiseta slender, biserrate and with proximal furcation strongly developed and abducted. Medially with one feathered spine-like seta and 4–5 long, simple setae. Maxillary palp slightly longer than galealacinia; two segmented. Segment I equal in length to segment II. Apex of segment II rounded without nipple and without excavation at inner distolateral margin. Setae on maxillary palp fine and simple over surface of segments I and II. Labium (Fig. 4F). Glossa basally broad, narrowing towards apex; shorter than paraglossa; inner margin with 10 spine-like setae increasing in length distally; apex with three robust pectinate setae; outer margin with 6 long, spine-like setae increasing in length distally; ventral surface with small medium, simple scattered setae. Paraglossa subrectangular slightly curved inward; apex rounded with three rows of long, robust distally pectinate setae in apical area and three medium simple setae in antero-medial area. Dorsally with a row of 6–7 long, spine-like setae near inner margin. Labial palp 3-segmented; segment I shorter than segments II and III combined; segment II slightly produced inward to form a moderately expanded lobe at distal corner; dorsally with a row of fine medium simple setae; segment III conical, slightly asymmetrical with a small concavity at inner apex; covered with short, stout, spine-like setae. Segments I, II and III with fine simple setae scattered over dorsal surface. Hind wing pads. Present, well developed. Foreleg (Fig. 5A). Ratio of foreleg segments 1.3:1.0:0.6:0.3. Femur length ca. 3× maximum width. Dorsal margin with a row of ca 24–25 long, stout, apically rounded setae; length of setae 0.25× maximum width of femur. Apex rounded with a row of 5–6 short, clavate setae and two groups of short, stout, pointed setae. Anterior surface with six robust setae and four small setae towards medially. Stout, lanceolate setae along ventral margin; villopore well developed. Dorsal margin of tibia with a row of fine simple setae; ventral margin with a row of short, spinelike setae, on apex one stout, pointed seta and a tuft of fine, simple setae; anterior surface scattered with stout, short, spatulate setae. Dorsal margin of tarsus with hair-like setae; ventral margin with 11–12 stout setae increasing in length towards apex, apex with one short, stout, spine-like seta. Claw (Fig. 5D) with a row of 11 denticles; distally pointed, 6–7 stripes, subapical setae absent. Middle leg (Fig. 5B). Dorsal margin with a row of ca 18–20 long, stout, apically rounded setae; length of setae 0.25× maximum width of femur. Dorsal margin of tarsus with hair-like setae; ventral margin with 11 stout setae increasing in length towards apex, apex with one short, stout, spine-like seta. Claw (Fig. 5D) with a row of 10 denticles; distally pointed, 7–8 stripes, subapical setae absent. Hind leg. Femur, tibia and tarsus same as middle leg; tarsal claw same as foreleg. Terga (Fig. 5H). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae. Posterior margin of tergum IV with apically rounded spines wider than long and with stripes. Gills (Figs 5F, G). Single lamellate gills present on segments I–VII. Margin with small denticles intercalating fine, simple setae, poorly visible trachea. Gill I as long as 2/3 of length of segment II; gill IV as long as length of segment V and ½ of segment VI combined, 2.3× length of gill I; gill VII as long as length of segment VIII. Paraproct (Fig. 5E). Distally not expanded, with 13–14 marginal stout spines.Surface scattered with microspores and fine simple setae, and with more patches of notched scales. Cercotractor with medium, marginal spines. Male imago. (Fig. 6A, C–E). Length: body 7.0– 7.2 mm; forewing 6.5 mm. Foreleg (Fig. 6A–B): femur 1.4 mm; tibia 2.2 mm; tarsi 0.3 mm. Cerci 10.5–10.8 mm. Head dark red; scape and pedicel medium to dark red; flagellum medium red; facetted surface of compound eyes reddish brown; lateral face reddish brown. Thorax: yellow to dark brown. Legs: femora, tibiae and tarsi bright yellow. Forewings (Fig. 6C) hyaline; pterostigma with 4 cross-veins generally reaching subcostal vein; double intercalary veins shorter than distance between corresponding main veins. Hind wings (Fig. 6D) with an erect costal spur at ¼ length of wing; two longitudinal veins reaching margin, none of them bifurcated. Abdomen: tergites I–VI pale yellow with a dark stripe parallel to distal margin, except VII–X light reddish without marking or pattern. Genitalia (Fig. 6E): with three-segmented gonopods, first and second segments almost fused, first segment without apophysis, abundant thin setae present on inner margin of second segment, third segment globular, forceps welldeveloped, apically flattened and without setae. Female imago (Fig. 6B). Length: body 7.8 mm; forewing 6.6 mm; foreleg: femur 1.6 mm; tibia 2.2 mm; tarsi 0.4 mm. Cerci 10.7 mm; Etymology. The new species is named after Dr. Kang (Japan), who has first established the genus Tenuibaetis. Distribution. North Western Himalaya (Himachal Pradesh), India. Diagnosis. Larva. Tenuibaetis kangi Kubendran, Vasanth & Subramanian sp. nov. can be distinguished from all known species of Tenuibaetis by the following combination of characters: (i) tergal color pattern dark brown with pale yellow transverse band on the posterior half of mesonotum, terga I–III dark brown, terga VI–VII dark brown and IX–X pale yellow (Fig. 1C); (ii) labrum dorsal submarginal arc of setae composed with 1+3 simple setae (Fig. 4A); (iii) left mandible: canine with 3+3 denticles (Fig. 4D); (iv) galea-lacinia with two simple, robust apical setae under crown (Fig. 4E); (v) outer margin of paraglossa with 6 long, spine-like setae increasing in length distally; (Fig. 4F); (vi) forefemur dorsal margin with 23–25 long, stout, apically rounded setae, anterior surface with distally 6 robust setae and 4 small setae towards medially (Fig. 5A); (vii) claw with a row of 11 denticles, subapical seta absent (Fig. 5D); (viii) gill I as long as 2/3 of length of segment II; (ix) paraproct distally not expanded, 13–14 marginal spines, with more patches of notched scales (Fig. 5E). Habitat. Tenuibaetis kangi sp. nov. collected in tributary of Beas River (Fig. 14B) (from 5.0– 5.5 m wide and 28–30 cm depth), near Baijnath village in the district of Kangra, Himachal Pradesh. This river is characterized by temperature ranges from 22–24 ° C at the time of sampling, average current velocity (0.9 m /sec) and mainly rock, gravel and pebbles at the bottom of river. The river banks covered with grasses. The new species of the larvae collected at an altitude of 998 m a.s.l. Usually specimens were collected on the surface of stones, gravel and submerged plants. Further specimens were found on surface of stones covered with filamentous green algae., Published as part of Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima & Sinha, Bikramjit, 2022, Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya, pp. 511-534 in Zootaxa 5196 (4) on pages 517-518, DOI: 10.11646/zootaxa.5196.4.3, http://zenodo.org/record/7235702

Tenuibaetis arduus (Kang & Yang, 1994) (Figs 7A–C, 8A–F, 9A–G) Baetis (Tenuibaetis) arduus in Kang et al n. sp. 1994: 29 Baetiella ardua Waltz & McCafferty, 1997: 136 n. comb. Tenuibaetis arduus Fujitani, Hirowatari & Tanida, 2003a: 127 n. comb. Material examined. 1 larva, INDIA, Arunachal Pradesh, West Kameng district, Chakparang stream, Dirang Valley, 27°25′20″N, 92°17′17″E, 11.III.2018, Coll. Bikramjit Sinha (Reg. No. I /E/331); 2 larvae, INDIA, Arunachal Pradesh, Tawang district, Nuranang falls, Jang, 27°35′23″ N, 91°58′54″E, 07.III.2018, Coll. Bikramjit Sinha (Reg. No. I /E/539). Description. Mature larva (Figs 7A–C). Body length 5.3–5.6 mm; cerci length 2.5–2.7 mm; paracercus length 1.5–1.8 mm; antenna 1.1× as long as head capsule length. Coloration (Figs 7A–C). Head dark brown medially pale with a pair of dark spots; base of clypeus pale yellow. Thorax brown with bright median, dorsal suture, mesothorax medially with bright striation and abdomen dorsally dark brown with two dark spots in medial area, abdominal segment IX with U-shaped pale white striation, segment X brownish white. Head, thorax and abdomen ventrally brown, somewhat brighter than dorsally. Legs light brown; femur dorsally pale and apical margin dark brown, distomedially dark brown; claws distally dark brown; caudal filaments brown. Morphology. Antenna (Fig. 8A). Scape and pedicel sub-cylindrical, flagellum with rounded spines apically and fine, simple setae on apex of segments. Labrum (Fig. 8B). Subrectangular with length 0.7× maximum width. Medial emargination of distal margin with a small, apically pointed process. Dorsally with many medium, fine, simple setae; submarginal arc of setae composed of 1+3 simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with two short, spine-like setae near lateral and anterolateral margin. Right mandible (Fig. 8D). Incisors fused. Outer and inner set of denticles with four denticles respectively. Prostheca stick-like, apically and distolaterally denticulate. Margin between prostheca and mola straight. Tuft of setae at apex of mola present. Left mandible. Incisors fused. Outer and inner set of denticles with three denticles respectively, plus one-minute, intermediate denticle. Prostheca robust, apically with small denticles and comb–shape structure. Margin straight between prostheca and mola. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically slender. Apex of mola tuft of setae present. Both mandibles with lateral margins almost straight; basal half with fine, simple setae scattered over dorsal surface. Hypopharynx (Fig. 8C). Lingua about as long as superlingua; lingua longer than wide; apically triangular with medial tuft of stout setae; distal half not expanded. Superlingua with distal margin straight; lateral margins rounded; fine, long, simple setae along distal margin; short, pointed setae along lateral margin. Maxilla (Fig. 8E). Galea-lacinia with one simple, robust apical seta under the crown. Inner dorsal row of setae with three dentisetae, distal dentiseta, tooth-like; middle dentiseta biserrate and proximal dentiseta, furcation strongly developed and abducted. Medially with one feathered spine-like seta and 4–5 long, simple setae. Maxillary palp 1.5× as long as length of galea-lacinia; two segmented. Segment I equal in length to segment II. Apex of segment II rounded without nipple. Setae on maxillary palp fine and simple setae over surface of segments I and II. Labium (Fig. 8F). Base of glossa broad, towards narrowing apex; paraglossa shorter; inner margin with eight spine-like setae increasing the length of distally; apex with three long and one medium, robust, pectinate setae; outer margin with five long, spine-like setae; ventral surface with fine, short setae. Paraglossa subrectangular, slightly curved inward; apex rounded, with three rows of long, simple, robust, pectinate setae apically; dorsally with three medium, simple setae; ventrally long setae near inner margin. Labial palp 3 segmented; segment I 0.7× of length of segments II and III combined. Segment II slightly produced inward to form a moderately expanded lobe at distal corner, dorsally with a row of 5–6 long, simple setae; Segment III conical, slightly pointed apically; covered with short, spine-like simple setae. Segments I, II and III with fine simple setae scattered over dorsal surface. Hind wing pads. Present, well developed. Foreleg (Fig. 9A). Ratio of foreleg segments 1.4:1.0:0.8:0.2. Femur. Length ca. 2.5× maximum width. Dorsal margin with a row of ca 21–22 long, curved, apically rounded setae; length of setae 0.22× maximum width of femur. Apex rounded with a row of short, stout, pointed setae, many stout lanceolate setae on lateral surface. Villopore well developed. Dorsal margin of tibia with a row of fine simple setae; ventral margin with a row of 6–9 spine-like setae and a tuft of long, fine, simple setae; anterior surface scattered with stout, spatulate setae. Tibia. Anterior surface with scattered stout setae, lanceolate. Tibio-patellar suture present on basal 2/3 area. Tarsus. Dorsal margin with a row of short, stout setae. Inner margin with a row of spine-like setae. Claw distally pointed and curved (Fig. 9C) with one row of 11 denticles and 5–6 stripes apically. Terga (Fig. 7A). Surface with scattered V-shaped scale bases and scattered fine, simple setae. Posterior margin of each segment a pair of small spots; tergum IX pale white with row of V- shaped spines. Gills (Figs 9D–F). Single lamellate gills present on segments I–VII. Margin with small denticles intercalating fine, simple setae. Tracheae obscure. Paraproct (Fig. 9G). Distally not expanded, with 13–14 marginal stout spines. Surface scattered with V-shaped scale bases, micropores fine, simple setae, with a patch of notched scales. Cercotractor with medium, marginal spines. Diagnosis: Tenuibaetis arduus can be differentiated by the following combination of characters: (i) labrum deeply cleft without “V” shaped marking medially (Fig. 8B); (ii) abdominal posterior marginal spines blunt (Fig. 7A); (iii) color pattern of thorax and abdomen distinct (Figs 7A–C); (iv) tracheation of gills obscure (Figs 9D–F); (v) claw with one row of 11 denticles (Fig. 9C). Distribution: Taiwan and India (Arunachal Pradesh). Remarks: This species was originally described from Taiwan based on larvae (Kang &Yang 1994). Present new record of the larvae Tenuibaetis arduus from Arunachal Pradesh is an extension distributional range of the species., Published as part of Kubendran, T., Vasanth, M., Subramanian, K. A., Gattolliat, Jean-Luc, Selvakumar, C., Jabeen, Fatima & Sinha, Bikramjit, 2022, Two new species and two new records of the genus Tenuibaetis Kang & Yang, 1994 (Ephemeroptera: Baetidae) from Indian Himalaya, pp. 511-534 in Zootaxa 5196 (4) on pages 522-526, DOI: 10.11646/zootaxa.5196.4.3, http://zenodo.org/record/7235702, {"references":["Kang, S. - C., Chang, H. - C. & Yang, C. - T. (1994) A revision of the genus Baetis in Taiwan. Journal of Taiwan Museum, 47, 9 - 44.","Waltz, R. D. & McCafferty, W. P. (1997) New generic synonymies in Baetidae (Ephemeroptera). Entomological News, 108, 134 - 140.","Fujitani, T., Hirowatari T. & Tanida, K. (2003 a) Genera and species of Baetidae in Japan: Nigrobaetis, Alainites, Labiobaetis, and Tenuibaetis n. stat. (Ephemeroptera). Limnology 4, 121 - 129. https: // doi. org / 10.1007 / s 10201 - 003 - 0105 - 2"]}

Larval key to the known species of subgenus Choroterpes in India 1. Gill 1 single (Fig. 13).................................................................................. 2 - Gill 1 double (Fig. 17; Selvakumar et al. 2015)........................................... Choroterpes (C.) petersi 2. Upper and lower lamellae of gills 2–7 broad (Figs 13–16; Selvakumar et al. 2017)............... Choroterpes (C.) kaegies - Upper and lower lamellae of gills 2–7 not broad (Figs 14–16)..................... Choroterpes (C.) andamanensis n. sp.

Megaglena agasthiya Vasanth, Subramanian & Selvakumar n. sp. (Figs 38���56) Material examined: Holotype: male larva, INDIA, Kerala, Trivandrum district, Peppara Wildlife Sanctuary, Pandipath stream, 8.67741�� N, 77.19390�� E; Alt. 1326 m; 19.i.2019, coll. M. Vasanth (Reg. No. I /E/436). Paratypes: 5 larvae, same data as holotype (Reg. No. I /E/437). Mature larva. Length: body 12.5���13.5 mm; antennae 2.6���3.0 mm; cerci 6.5���7.0 mm; paracercus 7.2���7.5 mm. General coloration yellowish brown (Figs 38���39). Head. Brown, washed with yellow. Upper portion of eyes conspicuously large and red (Fig. 38). Antennae pale yellow. Labrum (Figs 41���42): deep ���U��� shaped cleft on anteromedian emargination with blunt crenation on either side; dorsum with two rows of setae; length of labrum �� times of width. Hypopharynx (Fig. 43): lingua with well developed lateral processes, with anterior margin cleft; superlingua with row of setae on anterior margin. Mandibles (Figs 44���45): translucent, incisors and molars dark brown; scattered setae and tuft of setae laterally, inner incisor longer than outer one. Maxilla (Fig. 46): Segment I of maxillary palp longer than segment II, segment II shorter than segment III, segments I and III subequal in length, segment III with long setae at apex; outer margin of segment II with long setae; inner margins of segments II and III with short setae. Labium: palps 3-segmented, segment I broader with thick lateral setae, segments II and III subequal in length, segment III tapering at apex with a row of 5 conspicuous setae on the dorsal surface (Fig. 47). Thorax. Pale yellowish brown, irregularly washed with dark brown; lateral margins of pronotum pale yellow with diffuse black markings (Fig. 38). Legs pale yellow; coxae brown; all femora with large mesal macula dorsally. Foreleg (Fig. 48): outer surface of femur with rows of thick and scattered hair-like setae; inner surface with two rows of small stout setae, four prominent stout setae directed towards the distal end; inner surface of tibia with thick setae. Midleg (Fig. 49): dorsal surface of femur with 3 rows of short thick setae; row of short stout setae on midline; inner surface with two rows of small stout setae; tibia with rows of short setae. Hindleg (Fig. 50): femur with median brown macula on outer surface, with rows of thick and scattered hair-like setae; dorsal surface with 3 rows of short setae; inner surface with two rows of small setae; inner surface of tibia with thick setae; outer surface with few hairlike setae. Claws with 7���10 denticles which progressively increase in size apically (Fig. 51). Abdomen. Terga I���X yellowish brown with black posterior margins; terga I���X with yellowish stripe medially; posterolateral spines on abdominal segments IV���IX progressively larger posteriorly, segments VII���IX with pointed spines (Fig. 39���40). Gills on segments I���VII; gill I slender, lanceolate and bifid without branched tracheae; gills IV��� VI broader from the base to middle, tapering distally (Figs 52���53). Subanal plate deeply cleft (Figs 55���56). Terminal filament longer than cerci; caudal filaments with setae of each segment, shorter than length of corresponding segment. Adult: Unknown. Etymology: This species is named after the mythological Hindu sage Agasthya, who is believed to reside in the hills of the Southern Western Ghats from where the type specimens were collected. Treat as noun in apposition. Distribution: Peppara wildlife sanctuary, Kerala, India. Diagnosis: Megaglena agasthiya n. sp. can be differentiated from the only species, M. brincki Peters & Edmunds (1970) from Sri Lanka by the following character: (i) hind femur with dark band at mid length (Fig. 50), in contrast to M. brincki, which has dark band subapically (Peters & Edmunds 1970). Habitat: Larvae of Megaglena agasthiya n. sp. inhabit a small (from 2���3 m wide) mountain stream (Pandipath stream) which is typical in the upper mountain zone (up to 1320 m a.s.l.) of the Peppara Wildlife Sanctuary, Trivandrum District, Kerala (Fig. 60). The stream is characterized by medium water temperature (18���20��С at the time of sampling), average current velocity and sandy bottom with leaf litter. The new species were found with the larvae of the Choroterpes sp., Baetis sp. and Dudgeodes sp. Discussion: Genus Megaglena was established by Peters & Edmunds (1970) based on collections of larvae and adults from several localities in Sri Lanka during Swedish Ceylon expedition from Lund University Sweden in 1962. Peters & Edmunds (1970) has given diagnostic generic features of Megaglena Peters & Edmunds 1970 based on study of larvae and respective adults collected from the same locality. The present description of Megaglena agasthiya n. sp. from southern Western Ghats streams in Kerala state of India is extension of the generic range north of Sri Lanka in adjacent southern India. Interestingly, presence of a row of setae interspersed with spines on the outer margins of fore femora is a character shared with Edmundsula Sivaramakrishnan 1985 of southern India and Sangpradubina Boonsoong & Sartori 2016 of Thailand. The phylogenetic relationships of Gondwanan atalophlebiid genera can be understood only when integrated morphological and molecular studies of this cluster of genera are undertaken as pointed already., Published as part of Vasanth, M., Subramanian, K. A., Selvakumar, C., Kubendran, T. & Sivaramakrishnan, K. G., 2021, Three new species of Atalophlebiinae (Ephemeroptera: Leptophlebiidae) of India with a new record of the genus Megaglena Peters and Edmunds, 1970, pp. 56-70 in Zootaxa 5076 (1) on pages 64-68, DOI: 10.11646/zootaxa.5076.1.7, http://zenodo.org/record/5763329, {"references":["Peters, W. L. & Edmunds, G. F. Jr. (1970) Revision of the generic classification of the Eastern Hemisphere Leptophlebiidae (Ephemeroptera). Pacific Insects, 12 (1), 157 - 240.","Sivaramakrishnan, K. G. (1985) New genus and species of Atalophlebiinae (Ephemeroptera: Leptophlebiidae) from southern India. Annals Entomological Society of America, 78, 235 - 239.","Boonsoong, B. & Sartori, M. (2016) Sangpradubina, an astonishing new mayfly genus from Thailand (Ephemeroptera: Leptophlebiidae: Atalophlebiinae). Zootaxa, 4169 (3), 587 - 599. https: // doi. org / 10.11646 / zootaxa. 4169.3.11"]}

Edmundsula meghamalaiensis Vasanth, Subramanian & Selvakumar n. sp. (Figs 17–37) Material examined: Holotype: ♀ immature larva, INDIA, Tamil Nadu, Theni district, Suruli colony, Upper Manalar stream; 09.59167 N, 077.34261 E; Alt. 1530 m; 03.iii.2019, coll. M. Vasanth (Reg. No. I /E/433). Paratypes: 10 larvae (Reg. No. I /E/434), same data as holotype; 14 larvae, Kerala, Trivandrum district, Peppara Wildlife Sanctuary, Pandipath stream; 08.67741 N, 077.19390 E, Alt. 1326 m; 19.i.2019, coll. M. Vasanth (Reg. No. I /E/435). Mature larva. Length: body 8.5–9.0 mm; antennae 3.2–3.5 mm; cerci 6.5–7.0 mm; paracercus 7.2–7.5 mm. General coloration dark brownish yellow (Fig. 17). Head. Dark brown, washed with pale yellow. Upper portion of male compound eye reddish, lower portion black. Antennae white. Labrum (Figs 18–19): dorsum with two rows of thin, long setae; anterior region with a row of feather like setae ventrally; anteromedian emargination with moderate ‘V’ shaped cleft and without denticles. Hypopharynx (Fig. 20): lingua with well developed lateral process; anterior margin deeply cleft; superlingua with a row of setae on anterior margin. Mandibles: (Figs 21–22) translucent, with dark brown incisors and molars; lateral margins with scattered setae, inner incisor slightly longer than outer one. Maxilla (Fig. 23): segments I– III of palp equal in length, apical segment not tapering at apex. Labium (Figs 24–25): palps 3-segmented, segments II – III narrower, with row of thick setae on dorsal margin of third segment; outer and inner margins of palp with row of long and pointed setae; segment I slightly longer than segment II, segment III shorter than segment II, tapering at apex. Thorax. Pale yellowish brown, irregularly washed with dark brown; pronotum with lateral margins white; dark brownish with diffuse hypodermal markings. Legs: brownish yellow; coxae brown; outer surface of all femora with long, thick and thin setae; dorsal surface of foreleg with short stout setae as a group in the distal region; pale macula on distal end (Fig. 26); femur of midleg moderately developed with numerous short stout setae on dorsal surface (Fig. 27); dorsal surface of hindfemora with numerous short stout setae (Figs 28–29). Fore and mid tibia with thick feathered setae and long stout setae; hind tibia with thick feathered setae (Fig. 30). Claws with denticles, progressively larger from the middle, apical denticle much larger (Fig. 31). Abdomen. Terga I–X dark yellowish brown with diffuse hypodermal markings; terga I– VI with yellowish streaks laterally; terga IV–IX with posteriolateral spines, progressively larger posteriorly, spines on terga VII–IX pointed (Fig. 36). Gills on segments I–VII; gill I slender and lanceolate with branched tracheae; dorsal and ventral portions of lamellae of gills II –VII wider, long and smoothly tapered at apex (Figs 32–35). Subanal plate deeply cleft in male and female larva (Figs 36–37). Paracercus longer than cerci; caudal filaments with whorl of setae on alternate segments, setae shorter than length of corresponding segment. Adult. Unknown. Etymology. This species is named after the type locality, Meghamalai WLS, Theni District, Tamil Nadu, India. Distribution. Southern Western Ghats, India (Tamil Nadu and Kerala). Diagnosis. Edmundsula meghamalaiensis n. sp. can be distinguished from the previously described species, E. lotica Sivaramakrishnan 1985 by the following combination of larval characters: (i) anteromedian emargination of labrum with moderate ‘V’ shaped cleft and without denticles (Figs 18–19); (ii) segment I–III of maxillary palps shorter and apical segment not tapering at apex (Fig. 23); (iii) segment II–III of labial palp narrower and with a row of thick setae on the dorsal margin of third segment (Figs 24–25); (iv) distal region of dorsal surface of the foreleg with a group of short spines (Fig. 26). Habitat: Larvae of Edmundsula meghamalaiensis n. sp. inhabit first order (from 2–3 m wide) mountain stream (Manalar stream, 1530 m a.s.l.) of the Meghamalai Wildlife Sanctuary, Theni District, Tamil Nadu (Figs 58–59). The stream is characterized by medium water temperature (18–22°С at the time of sampling) and average current velocity. Larvae were collected from cobbles and pebbles where the new species was found with the larvae of the Baetis sp., Afronurus sp., Choroterpes sp. and Dudgeodes sp. Discussion: With an array of several plesiomorphic character states, Edmundsula is a genus of Gondwanian origin, presently the genus is endemic to southern peninsular India, which may have phylogenetic links with genera disjunctly distributed in Sri Lanka, Madagascar, South Africa and Australia. However, this requires in depth study through further exploration in respective areas. Furthermore, Sivaramakrishnan (1985) suggested a tenuous link of Edmundsula Sivaramakrishnan 1985 with Neozephlebia Penniket 1961 from New Zealand due to the dorsolateral expansion of the glossae in both the genera. Dense rows of setae on the outer margins of fore and middle legs in Edmundsula Sivaramakrishnan 1985 and in Indialis Peters & Edmunds 1970, another genus endemic to southern India apparently show relationship established the genus Sangpradubina from Thailand as pointed out by Boonsoong & Sartori (2016); Kluge (2020) recognized to given the morphological notes of femoral and tibial setation of genus Thraulodes Ulmer 1920 from Panama and Peru. These phylogenetic riddles can only be solved when combined morphological and molecular studies of both larval and respective alate stages of all these Gondwanan genera with intensified international collaboration.

Choroterpes (Choroterpes) andamanensis Vasanth, Subramanian & Selvakumar n. sp. (Figs 1–16) Material examined: Holotype: male larva, INDIA, Andaman and Nicobar Islands, Botanical Garden, Nayachaar; N 11.5738°, E 92.6741°; Alt. 54m.; 16.xi.2018, coll. K. A. Subramanian (Reg. No. I /E/438). Paratypes: 3 larvae (Reg. No. I /E/439), same data as holotype. Mature larva. Length: body, 4.3–5.0 mm; antennae, 2.8–3.0 mm; cerci, 5.2–5.5 mm; paracercus, 5.8–6.0 mm. General coloration yellowish brown (Figs 1–2). Head. Dark brown, washed with yellow. Upper portion of male compound eye reddish black. Antennae whitish yellow (Fig. 1). Labrum (Fig. 3): dark brown; anteromedian emargination shallow, broad with five blunt denticles. Hypopharynx (Fig. 4): lingua with well developed lateral process, with cleft anterior margin. Mandibles (Figs 5–6): translucent, dark brown and pale brown medially; lateral margins with scattered setae, inner incisor slightly longer than outer one. Second segment of maxillary palp subequal in length of segment I, segment III approximately ¾ length of segment II (Fig. 7). Labium (Fig. 8): glossae with plate-like thick setae on ventral surface and dense row of fewer setae on dorsal surface; paraglossae with denser but thinner setae on dorsal surface; first segment of labial palp with thick setae on lateral margins, second segment with hair-like setae on lateral margin, apical segment with thick and fine setae and small tufts; length of segment I subequal to segment II, segment III approximately ¾ length of segment II. Thorax. Yellowish brown, irregularly washed with dark brown; pronotum dark yellowish brown with diffuse black markings medially. Meso- and metathorax yellowish brown tinged with dark brown or black laterally. Legs (Figs 9–11): yellowish brown; each femur with a brown macula on middle and distal region; forefemur with thick setae on the dorsal surface, mid and hind femora with several well developed thick setae on dorsal surface; each femur with thick and thin setae on outer margin; fore and mid tibiae with fine and thick setae on inner margin, and very sparse and thin setae on inner and outer margin; hind tibiae with thick and few feathered setae on surface; tarsi of all legs with several thin setae on inner margin and sparse setae on outer margins. Claws apically hooked with a row of 8–9 denticles (Fig. 12). Abdomen. Terga I–X pale yellowish brown with diffuse black markings and spines on posterior margins; posterolateral margins of abdominal terga I– III with blunt denticles and IV–IX with pointed denticles, size of denticles progressively larger posteriorly. Sterna I–VII white and VIII–IX yellowish (Figs 1–2). Gills I–VII, well-tracheated, slender, gills II –VII with dorsal lamella larger than ventral (Figs 13–16). Sternum IX of male with deep apical cleft, sternum IX of female with apex entire and without emargination (Fig. 2). Caudal filaments pale yellow-brown; with a whorl of setae on alternate segments; setae shorter than length of corresponding segment. Adult. Unknown Etymology. The species named after the type locality, Andaman Islands. Distribution. Andaman Island (India). Diagnosis. Choroterpes (Choroterpes) andamanensis n. sp. can be distinguished from all known species of subgenus Choroterpes by the following characters: (i) anteromedian emargination of labrum broad with five blunt denticles (Fig. 3); (ii) gills II–VII with dorsal lamella larger than ventral (Figs 14–16). (iii) femur with brown macula on middle and distal region (Figs 9–11); and (iv) claw with a row of 8–9 denticles (Fig. 12). Habitat: Larvae of Choroterpes (Choroterpes) andamanensis n. sp. inhabit small (from 1.5–2 m wide) stream (Nayachaar) (Fig. 57) (up to 54 m a.s.l.) of the Port Blair district, Andaman Island. This stream is characterized by medium water temperature (25°С at the time of sampling), average current velocity and bottom substrate predominantly with pebbles, sand, leaf litter and silt particles. The new species was found with Baetis sp. Discussion. Presently, three species are recorded from the subgenus Choroterpes s. str. in India viz., Choroterpes (C.) petersi Tong and Dudgeon, 2003 from southern Western Ghats by Selvakumar et al., (2015) which was originally described from Hong Kong, Choroterpes (C.) kaegies Selvakumar, Subramanian & Chandra, 2017 described from Himachal Pradesh and Meghalaya and the present new species, Choroterpes (Choroterpes) andamanensis Vasanth, Subramanian & Selvakumar n. sp. from the Andaman and Nicobar Islands. The distribution of Choroterpes (C.) petersi Tong and Dudgeon, 2003 appears to be disjunct in its geographical range. Choroterpes (C.) kaegies Selvakumar, Subramanian & Chandra, 2017 is widely distributed in North and North-East India. Choroterpes (C.) andamanensis n. sp. is only known from Andaman Islands. However, extensive field surveys are required to explore the distribution of this subgenus in the Indian subcontinent.

Epeorus (Caucasiron) suspicatus Braasch, 2006b Diagnosis: This species could be distinguished by the following combination of characters: in larva (i) gills II–VII without papillae; and (ii) presence of spines on posterior margin of abdomen. Distribution: India (Himachal Pradesh) and Nepal. Remarks: The larva of this species was insufficiently described from Kulu-Valley, Himachal Pradesh (India) and Nepal by Braasch (2006b). Adult stages are unknown., Published as part of Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2021, Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India, pp. 499-522 in Zootaxa 4991 (3) on page 519, DOI: 10.11646/zootaxa.4991.3.4, http://zenodo.org/record/5042522, {"references":["Braasch, D. (2006 b) Iron suspicatus n. sp. (Ephemeroptera, Heptageniidae) aus Nepal und aus dem Kulu-Valley des Himalaja in Indien. Entomologische Nachrichten und Berichte, 50 (3), 125 - 128."]}

Epeorus (Epeorus) gilliesi Braasch, 1981 (Figs 68–84) Material examined: 1 larva, INDIA, Karnataka, Sharavathi river, below Jog falls, 26.xi.1928 [Reg. No. 7348/H13, ZSI, Kolkata]; 1 larva, Goa, Tambdi Surla, 17.ix.2017; coll. K. A. Subramanian [ZSI/ SRC-I /E-334]. Description: Mature larva: Body length 13.5 mm; length of caudal filaments 12 mm. Body generally brown (Fig. 68). Head: Length 1.7 mm, width 3.6 mm; brown (Fig. 68); subquadrangular; anterior and lateral margins convex, with rows of dense hair-like setae directed medially-dorsally-backward and pressed to head; posterior margin slightly concave. Compound eyes grayish black. Antennal scape, pedicels and flagellum brown. Labrum wide, dark brown, anterior margin with 14–15 denticles; long hair-like setae laterally (Fig. 71). Hypopharynx as in Fig. 72. Mandible with scattered setae along molar area; incisors well developed; outer incisor longer than inner incisor (Figs 73–74). Maxilla as in Fig. 75. Labium broad, glossae with V-shaped separation, subtriangular; paraglossae slightly expanded laterally; apical segment of palp acutely pointed, dorsal surface with dense row of comb setae (Fig. 76). Thorax: Pronotum pale brown; mesonotum darker brown with paramedian pair of darker spots anteriorly and pair of lateroparapsidal sutures curved inside posteriorly (Fig. 68). Legs (Figs 78–80): Femora brown; hypodermal spot on dorsal surface; dense row of long setae on outer margin; scattered stout setae on dorsal surface (Fig. 77); margin of tibia with dense hair-like setae. Claw with 5 denticles (Fig. 81). Abdomen: Abdominal terga brown, a row of spines on posterior margin of segment I–X, terga III–VIII with a pair of brown spots (Figs 68, 70); posterior margin of terga with rather short spines; segments II–VII with long posterolateral extensions; sterna pale with pair of brown color marking on each segments (Fig. 69). Gill I elongated, somewhat extended beneath of abdomen, middle pairs large widely rounded (Fig. 68); Gills II–VII without arched anal ribs (Figs 82–84). Cerci with row of hair-like setae dorsally. Diagnosis: Epeorus gilliesi can be distinguished from closely related species E. petersi by the following combination of characters: in larva (i) abdominal terga III–VIII with pair of brown spot (Figs 68–70); (ii) a row of spine on posterior margin of segment I–X (Figs 68–70); (iii) posterior edge of the gill 1 elongated (Fig. 82); and (iv) anterior margin of labrum with 14–15 denticles (Fig. 71). Distribution: India (Karnataka, Goa and Maharashtra). Remarks: The larva of this species was described from Khandala (Maharashtra), India by Braasch (1981); we provide a supplementary larval description based on our material from south India. Adult stages are unknown., Published as part of Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2021, Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India, pp. 499-522 in Zootaxa 4991 (3) on pages 508-513, DOI: 10.11646/zootaxa.4991.3.4, http://zenodo.org/record/5042522

Epeorus (Epeorus) aculeatus Braasch, 1990 (Figs 1–17) Material examined: 1 larva, INDIA, Arunachal Pradesh, Lower Subansiri district, Duskilo stream, 27.62776 N, 93.8437 E, 1662 m, 16.vi.2017, colls. K. A. Subramanian and M. Vasanth [ZSI/ SRC-I / E 289]; 6 larvae, Arunachal Pradesh, West Kameng district, Dirang, Showda village, Dirang river, 27.32675 N, 92.23180 E, 1877 m, 13.iii.2018, coll. Bikramjit Sinha [ZSI/ SRC-I / E 298]. Description: Larva: Body length 9.5 mm; length of cerci 11.5 mm. Body generally dark brown (Fig. 1). Head: Length 1.7 mm, width 2.4 mm; brown, (Fig. 1); subquadrangular; anterior and lateral margins convex, with rows of dense hair-like setae directed anteriorly; posterior margin slightly concave. Compound eyes black. Antennal scape and pedicel brown, flagellum pale. Labrum dark brown, deeply cleft with median notch on anterior margin; long hair-like setae laterally (Fig. 5). Hypopharynx: Lingua with anterolateral lobes; superlinguae slightly expanded, laterally with rows of dense hair-like setae (Fig. 6). Mandible without scattered setae along the molar; incisors serrated, outer incisor longer than inner incisor (Figs 7–8). Maxilla with row of hair-like setae medially, apical segment of palp with dense row of hair-like setae, basal segment of palp broad (Fig. 9). Labium broad, glossae with U-shaped separation, subtriangular; paraglossae slightly expanded laterally; apical segment of each palp pointed, dorsal surface with dense row of comb setae (Fig. 10). Thorax: Pronotum brown without clear marks; mesonotum somewhat darker brown with paramedian pair of darker spots anteriorly (Fig. 1). Legs: Femur brown; hypodermal spot on dorsal surface, outer margin with long setae; distal end with blunt spine (Figs 11–13); short stout blunt setae scattered on dorsal surface (Fig. 11a), tibia brown with long hair-like setae on outer margin; tarsi dark brown. Claw small with 3 denticles (Fig. 14). Abdomen: Abdominal terga dark brown, terga II–IX with pair of long, acute, submedian spines (Fig. 2); posterior margin of tergum with hair-like setae medially and with numerous minute spines on segments II–IX (Fig. 4); segments II–VII with long posterolateral extensions (Fig. 3); sterna pale yellowish without markings. Lamellae of gill I somewhat extended beneath of abdomen (Fig. 15). Gills II–VII with costal ribs arched and anal rib straight (Figs 16–17). Cerci with hair-like setae dorsally. Diagnosis: The larva of Epeorus (E.) aculeatus can be distinguished from other species of this genus by the following combination of characters: (i) posterior margin of abdominal terga II–IX each with pair of long, acute, submedian spines (Figs 1–2); (ii) anterior margin of labrum with deep median notch (Fig. 5); (iii) femur with short stout blunt setae scattered on dorsal surface (Fig. 11a). Distribution: Thailand and India (Arunachal Pradesh). Remarks: The larva of this species was described from Thailand by Braasch (1990) and male adult was described by Webb & McCafferty (2006); we provide a supplementary larval description based on our material, which represents the first record of the species for India., Published as part of Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2021, Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India, pp. 499-522 in Zootaxa 4991 (3) on pages 500-503, DOI: 10.11646/zootaxa.4991.3.4, http://zenodo.org/record/5042522, {"references":["Braasch, D. (1990) Neue Eintagsfliegen aus Thailand, nebsteinigen Bemerkungen zuderen generischem Status (Insecta, Ephemeroptera, Heptageniidae). Reichenbachia, 28 (2), 7 - 14.","Webb, J. M. & McCafferty, W. P. (2006) First description of the adult male of Epeorus aculeatus Braasch (Ephemeroptera: Heptageniidae). Zootaxa, 1277, 65 - 68. https: // doi. org / 10.11646 / zootaxa. 1277.1.5"]}

Epeorus lahaulensis Kapur & Kripalani, 1963 Diagnosis: The species Epeorus lahaulensis can be identified by the following combination of characters: in subimago (i) abdominal tergites brownish, each tergum darker posteriorly, sterna much paler; (ii) gonostyli 3 segmented, first segment longest, second segment slightly longer than third; (iii) margin of genital base convex; and (iv) penis long, broad apically and slightly divergent laterally, spines present ventrally just below the apex. Distribution: Known only from the type locality, Sissu, Lahaul Valley, Himachal Pradesh. Remarks: The subimago of this species was described from Himachal Pradesh by Kapur & Kripalani (1963). Adult and larval stages are unknown. Therefore, any subgeneric attribution is not possible., Published as part of Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2021, Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India, pp. 499-522 in Zootaxa 4991 (3) on page 516, DOI: 10.11646/zootaxa.4991.3.4, http://zenodo.org/record/5042522, {"references":["Kapur, A. P. & Kripalani, M. B. (1963) The mayflies (Ephemeroptera) from the north - western Himalaya. Records of the Indian Museum, 59, 183 - 221."]}

Epeorus (Epeorus) bifurcatus Braasch & Soldán, 1979 (Figs 18–34) Material examined: 2 larvae, India, Arunachal Pradesh, West Kameng, Dirang, Showda village, Dirang river, 27.3267528 N, 92.2318027 E, 1877 m, 13.iii.2018, coll. Bikramjit Sinha [ZSI/ SRC-I /E/297]; 1 larva, India, Arunachal Pradesh, Upper Dibang Valley, Mipi, Mipi river, 28.96643 N, 95.8061 E, 1455 m, 31.x.2017, coll. Anil Kumar & Party [ZSI/ SRC-I /E/312]; 15 larvae, India, Arunachal Pradesh, West Kameng district, Sangti valley, Khechalu, Khendo Rong (stream), 27.420841 N, 92.269538 E, 1790 m, 12.iii.2018. coll. Bikramjit Sinha [ZSI/ SRC-I /E/320]. Description: Larva: Body length 9.8 mm; length of cerci 10.4 mm. Body generally dark brown (Fig. 18). Head: Length 1.7 mm, width 2.9 mm; light brown (Fig. 18); subquadrangular; anterior and lateral margins convex, with rows of hair-like setae directed anteriorly. Compound eyes black. Antennae with scape, pedicels and flagella light brown (Fig. 22). Labrum brown with deep median notch on anterior margin, long hair-like setae laterally (Fig. 23). Hypopharynx as in Fig. 24. Mandibles without scattered setae along the molar area; incisors serrated, outer incisor longer than inner incisor (Figs 25–26). Maxilla as in Fig. 27. Labium (Fig. 28) as in the previous species. Thorax: Pronotum pale brown with indistinct band in middle and pair of dark spots; mesonotum brown (Fig. 18). Legs (Figs 29–31): Femora light brown, hypodermal spot on middle, outer margin with long setae and dark brown maculae medially; distal end with blunt spine; dorsal surface with scattered stout short thickened setae (Fig. 31a); tibia pale brown with long hair-like setae on outer margin; claw with 3 small denticles (Fig. 32). Abdomen: Abdominal terga light brown, terga II–IX with pair of short submedian spines (Figs 18, 20); tergum II yellowish, terga III and IV with indistinct pale patches on middle, terga V–VIII with light middle band; terga II–IX with small setae along midline (Fig. 21); segments II–VII with long postero-lateral extensions; sterna light yellowish without markings (Fig. 19). Gill I triangular (Fig. 33); gills II–VII oval (Fig. 34). Cerci with row of hairlike setae dorsally. Diagnosis: The larva of Epeorus (E.) bifurcatus can be distinguished from other species of this genus by the following combination of characters: (i) posterior margin of abdominal terga II–IX with pair of short submedian spines (Figs 18 & 20); terga II–IX with small setae along midline (Fig. 21); and (iii) gill I larger than others (Fig. 33). Distribution: Vietnam, Thailand and India (Arunachal Pradesh). Remarks: The larva of this species was described from Vietnam by Braasch & Soldán (1979). Subsequently, Nguyen & Bae (2004) redescribed the larva of E. bifurcatus based also on specimens from Vietnam. Braasch & Boonsoong (2010) reported this species from Thailand; we provide a supplementary larval description based on our material, which represents the first record of the species for India., Published as part of Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2021, Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India, pp. 499-522 in Zootaxa 4991 (3) on page 503, DOI: 10.11646/zootaxa.4991.3.4, http://zenodo.org/record/5042522, {"references":["Nguyen, V. V. & Bae, Y. J. (2004) Larvae of the heptageniid mayfly genus Epeorus (Ephemeroptera: Heptageniidae) from Vietnam. Journal of Asia-Pacific Entomology, 7, 19 - 28. https: // doi. org / 10.1016 / S 1226 - 8615 (08) 60197 - 1","Braasch, D. & Boonsoong, B. (2010) A contribution to the Heptageniidae (Insecta, Ephemeroptera) of Thailand and Malaysia. Zootaxa, 2610, 1 - 26. https: // doi. org / 10.11646 / zootaxa. 2610.1.1"]}

Epeorus (Epeorus) unicornutus Braasch, 2006a (Figs 35–49) Material examined: 2 larvae, INDIA, Arunachal Pradesh, Lower Subansiri district, Pa stream 27.74791 N, 94.0346 E, 284.2 m, 14.vi.2017, colls. K. A. Subramanian and M. Vasanth [ZSI/ SRC-I / E 287]; 2 larvae, INDIA, Arunachal Pradesh, West Kameng district, Dirang, Showda village, Dirang river, 27.3267528 N, 92.231802 E, 1877 m, 13.iii.2018, coll. Bikramjit Sinha [ZSI/ SRC-I / E 296]; 2 larvae, INDIA, Arunachal Pradesh, Lower Dibang valley district, Roing, Iphipani river, 28.18728 N, 95.84094 E, 488 m, 04.iv.2016, coll. Santabala & Party [ZSI/ SRC-I / E 309]. Description: Mature larva: Body length 11.8 mm; length of cerci 12 mm. Body generally pale brown. (Fig. 35). Head: Length 1.9 mm, width 2.8 mm; pale brown (Fig. 35); subrectangular; anterior and lateral margins convex, with rows of dense hair-like setae directed anteriorly; posterior margin slightly concave. Compound eyes blackish, antennal scape, pedicels and flagellum pale brown. Labrum wide, dark brown, anterior margin with 11–12 denticles, long hair-like setae laterally (Fig. 39). Hypopharynx as in Fig. 40. Mandible brown with scattered setae along the molar area; incisor serrated; outer incisor longer than inner incisor (Figs 41– 42). Maxilla as in Fig. 43. Labium: glossae broad with V-shaped separation, subtriangular; paraglossae slightly expanded laterally; apical segment of palp pointed, dorsal surface with dense row of comb setae (Fig. 44). Thorax: Pronotum pale brown; mesonotum light brown (Fig. 35). Femora light brown with distinct patches; dorsal surface of all femora with two brown maculae medially (Fig. 45) and stout setae (Fig. 45A); femora of distal end with a prominent pointed spine on all legs (Fig. 45). Claw with 4 denticles (Fig. 46). Abdomen: Abdominal terga pale brown without special marks (Fig. 35); posterior margin of abdominal terga I–X each with a row of spines (Figs 37– 38); terga II–X with a single acute median and medially prominent pointed spine (Fig. 35); tergum X with short spines with minute hair-like setae on posterior margin (Fig. 38); terga II–VII with long posterolateral extensions (Fig. 36); sterna pale with brown markings of oblique stripes medially and medio-lateral stripes laterally. Lamellae of gill I somewhat extended beneath of abdomen (Fig. 47). Gills II–VII with anal rib straight (Figs 48–49); gill faces with exception of marginal parts brownish tinged with black. Cerci with row of small hair-like setae dorsally. Diagnosis: The larva of Epeorus (E.) unicornutus can be distinguished from other species of this genus by the following combination of characters: (i) posterior margin of abdominal terga I–X each with a row of spines (Fig. 35); (ii) terga II–IX each with acute median and medially prominent pointed spine (Figs 35–38); (iii) tergum X with short spines with minute hair-like setae on posterior margin (Fig. 38) and (iv) anterior margin of labrum with 11–12 denticles (Fig. 39). Distribution: Nepal, Thailand and India (Arunachal Pradesh). Remarks: The larva of this species was described from Nepal by Braasch (2006a) and reported from Thailand by Boonsoong and Braasch (2013); we provide a supplementary larval description based on our material, which represents the first record of the species for India., Published as part of Vasanth, M., Selvakumar, C., Subramanian, K. A., Sivaramakrishnan, K. G. & Sinha, Bikramjit, 2021, Contribution to the study of Epeorus Eaton, 1881 (Ephemeroptera: Heptageniidae) from India, pp. 499-522 in Zootaxa 4991 (3) on pages 503-508, DOI: 10.11646/zootaxa.4991.3.4, http://zenodo.org/record/5042522, {"references":["Braasch, D. (2006 a) Neue Eintagsfliegen der Gattungen Epeorus und Iron aus dem Himalaja (Ephemeroptera, Heptageniidae). Entomologische Nachrichten und Berichte, 50 (1 - 2), 79 - 88.","Boonsoong, B. & Braasch, D. (2013) Heptageniidae (Insecta, Ephemeroptera) of Thailand. ZooKeys, 272, 61 - 93. https: // doi. org / 10.3897 / zookeys. 272.3638"]}