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Aenigmatoconcha mitis (Pfeiffer, 1863) comb. nov. Figs 1, 2B, 4C–F, 6, 10B Helix mitis Pfeiffer, 1863 [1862]: 268. Type locality: Lao Mountains, Camboja [Lao Mountains, Cambodia]. Helix mitis – Pfeiffer 1868: 141. — Tryon 1886: 171. Ariophanta (Kaliella) mitis – Fischer 1891: 21. Hyalinia mitis – Fischer & Dautzenberg 1904: 396. Macrochlamys (?) mitis – Inkhavilay et al. 2019: 78, 79, fig. 37b. Material examined Syntypes CAMBODIA • 2 sh; “Lao Mountains, Camboja ” [Lao Mountains, Cambodia]; NHMUK ex. Cuming collection. Other material THAILAND • 37 sh, 16 sp; Nakhon Sawan Province, Mueang District, Limestone outcrops at Wat Tham Bo Ya; 15º43′47.3″ N, 99º56′44.7″ E; CUMZ 7708 • 30 sh, 15 sp; same collection data as for preceding; CUMZ 7885 • 8 sh, 21 sp; Nakhon Sawan Province, Krok Phra District, Limestone outcrops at Wat Khao Tham Phra; 15°33′30.2″ N, 99°57′28.1″ E; CUMZ 7849 • 3 sp; Kanchanaburi Province, Sai Yok District, Limestone outcrops at Wat Thep Thepa Satthatham; 14°03′56.6″ N, 99°11′45.7″ E; CUMZ 7913 • 21 sh, 24 sp; Kanchanaburi Province, Mueang District, Limestone outcrops at Wat Tham Charoentham; 13°55′59.1″ N, 99°27′59.9″ E; CUMZ 7687 • 3 sp; Kanchanaburi Province, Tha Muang District, Limestone outcrops at Wat Tham Faet; 13°57′52.5″ N, 99°34′56.1″ E; CUMZ 7914 • 30 sh, 1 sp; Kanchanaburi Province, Dan Makham Tia District, Limestone outcrops at Wat Tham Khao Cha Ang; 13°48′08.4″ N, 99°26′33.2″ E; CUMZ 7247 • 4 sh, 3 sp; Phetchaburi Province, Khao Yoi District, Limestone outcrops at Wat Khiri Wong; 13°20′03.2″ N, 99°45′19.0″ E; CUMZ 7917 • 1 sh, 15 sp; Phetchaburi Province, Khao Yoi District, Limestone outcrops at Wat Puang Malai; 13°18′46.0″ N, 99°47′02.2″ E; CUMZ 7921 • 9 sh; same collection data as for preceding; CUMZ 7938 • 5 sh, 14 sp; Phetchaburi Province, Tha Yang District, Limestone outcrops at Wat Khao Krachiu; 12°57′41.3″ N, 99°54′49.3″ E; CUMZ 7918 • 3 sh, 16 sp; Phetchaburi Province, Cha-am District, Limestone outcrops at Khao Nang Panthurat; 12°50′20.5″ N, 99°57′11.6″ E; CUMZ 7920 • 2 sh, 2 sp; Phetchaburi Province, Cha-am District, Limestone outcrops at Tham Chaeng Bureau of Monks; 12°49′44.3″ N, 99°56′27.1″ E; CUMZ 7919 • 4 sh, 7 sp; Prachuap Khiri Khan Province, Mueang District, Limestone outcrops at Khao Lom Muak; 11°47′03.0″ N, 99°48′56.3″ E; CUMZ 7915 • 3 sh, 8 sp; Prachuap Khiri Khan Province, Mueang District, Limestone outcrops at Khao Ta Mong Lai; 11 o 50′07.3″ N, 99 o 49′50.1″ E; CUMZ 7916. Description SHELL (Fig. 4C–F). Shell depressed to globosely depressed, medium-sized (width 12.3–18.1 mm, height 6.9–9.9 mm), rather thin, and translucent. Shell surface smooth and glossy. Shell colour whitish to very pale horny-white. Whorls: 5–5½, regularly increasing in size; varix present; suture rather wide and shallow. Spire rather elevated. Last whorl broad and well-rounded. Aperture obliquely oval-lunate in shape; peristome simple. Columellar margin simple, slightly expanded near umbilicus. Umbilicus open and deep. EXTERNAL FEATURES (Fig. 2B). Living snails with reticulated skin and pale yellowish to dark grey body. Five well-developed mantle lobes; left and right shell lobes thin, pale yellowish, spread with small whitish dots, and left shell lobe larger than right shell lobe. Three dorsal lobes broad and crescentshaped; right dorsal lobe larger than anterior and posterior left dorsal lobes. Caudal fossa present; caudal horn raised, rather large, and whitish to pale fleshy-grey in colour. GENITALIA (Fig. 6). Atrium (at) enlarged and very short. Penis (p) long, cylindrical, and with slightly thick penial sheath (ps) encircling about half of penis length. Inner sculpture of penis with very small and oblique wrinkled penial pilasters (pp), and one large longitudinal fold running the length of the entire penis chamber. Epiphallus (e1 + e2) approximately as long as penis: e1 slender and narrower than penis, and e2 shorter and bulbous shape. Inner sculpture of e1 with very small thin longitudinal folds to nearly smooth surface with one thickened longitudinal fold, and inner sculpture of e2 with large papillae arranged in oblique rows. Epiphallic caecum (ec) very short; penial retractor muscle (prm) thin and attached at tip. Flagellum (fl) small and rather short. Vas deferens (vd) very long and thin. Vagina (v) very short and enlarged. Gametolytic duct (gd) long, slender, and enlarged near vagina; gametolytic sac (gs) very large and oblong shape. Free oviduct (fo) cylindrical, long, and encircled with thick tissue near vagina. RADULA (Fig. 10B). Teeth arranged in anteriorly V-shaped rows with half row consisting of about 76– 79 teeth at middle plate. Central teeth symmetrical monocuspid, and spatulate-shaped with curved cusp. Lateral and marginal teeth undifferentiated, asymmetrical monocuspid, spatulate-shaped with curved cusp, and outermost teeth gradually reduced in size. Distribution The distribution of Aenigmatoconcha mitis is wider than all other recognised species. This species can be found in limestone areas ranging from central (Nakhon Sawan Province) to southern (Prachuap Khiri Khan Province) Thailand (Fig. 1). Remarks This species was originally described by L. Pfeiffer (1863) based on specimens in the collection of H. Cuming obtained from Henry Mouhot. The collection locality was brief: “Lao Mountains, Camboja ”. However, Mouhot’s recorded localities were generally imprecise and referred to a wide geographical area, for example “ Siam ”, “Lao Mountains, Camboja ” and “ Camboja ”. This has made it difficult to infer more precise type localities of several land snail species described from Mouhot’s specimens. No additional specimen records or literature references are available for this species until now. The most recent works on land snails from Laos and southern Cambodia confirmed the existence of A. mitis (Inkhavilay et al. 2019; Sutcharit et al. 2020c). Based on the recorded itinerary, H. Mouhot had travelled to “Pechaburi” [Petchaburi Province] in 1861, and clearly stated that he had visited caves and several hills during his four-month stay (Mouhot 1864: 57; Ashburton 1864: map). We have surveyed several limestone hills in western and peninsular Thailand and encountered numbers of empty shells and living specimens that well-matched with the type specimens of “ Helix mitis Pfeiffer, 1863 ” (Fig. 4C). Therefore, peninsular Thailand (Petchaburi Province; Fig. 1) might be the area where H. Mouhot collected this species. Aenigmatoconcha mitis exhibits a rather wide range of shell shape variation from depressed (Fig. 4F) to somewhat globose (Fig. 4C, D). However, the genitalia of these shell morphs are identical and the COI phylogeny also supports that all shell morphs are grouped together within the A. mitis clade (Fig. 2)., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2021, Systematic revision of the limestone karst-restricted land snail genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with description of a new species, pp. 55-82 in European Journal of Taxonomy 767 on pages 66-70, DOI: 10.5852/ejt.2021.767.1487, http://zenodo.org/record/5528134, {"references":["Pfeiffer L. 1863. Descriptions of thirty-six new land shells from the collection of H. Cuming, Esq. Proceedings of the Zoological Society of London 30: 268 - 278. [Published in parts, dates follow Duncan (1937)].","Pfeiffer L. 1868. Monographia heliceorum viventium supplementum tertium: sistens descriptiones systematicas et criticas omnium hujus familiae generum et specierum hodie cognitarum, volume quintum. F. A. Brockhaus, Lipsiae.","Tryon Jr. G. W. 1886. Manual of Conchology; Structural and Systematic. With illustrations of the species. Second Series: Pulmonata. Volume II. Zonitidae. Academy of Natural Sciences, Philadelphia.","Fischer P. 1891. Catalogue et distribution geographique des Mollusques terrestres, fluviatiles & marins dune partie de lIndo-Chine (Siam, Laos, Cambodge, Cochinchine, Annam, Tonkin). Imprimerie Dejussieu Pere et Fils, Autun. https: // doi. org / 10.5962 / bhl. title. 14809","Fischer H. & Dautzenberg P. 1904. Catalogue des Mollusques terrestres et fluviatiles de lIndo-Chine orientale cites jusqu' a ce jour. Mission Pavie, Etudes diverses 3: 390 - 450. https: // gallica. bnf. fr / ark: / 12148 / bpt 6 k 8814596 [accessed 22 July 2021]","Inkhavilay K., Sutcharit C., Bantaowong U., Chanabun R., Siriwut W., Srisonchai R., Pholyotha A., Jirapatrasilp P. & Panha S. 2019. Annotated checklist of the terrestrial molluscs from Laos (Mollusca, Gastropoda). ZooKeys 834: 1 - 166. http: // doi. org / 10.3897 / zookeys. 834.28800","Tumpeesuwan C. & Tumpeesuwan S. 2017. Discovery of an overlooked helicarionid land snail (Helicarionidae: Durgellinae) from northeastern Thailand, with description of a new genus and new species, and a note on radula morphology and genital system. Raffles Bulletin of Zoology 65: 174 - 181. Tumpeesuwan C. & Tumpeesuwan S. 2018. Aenigmatoconcha sumonthai, a new helicarionid land snail from Chumphon Province, Southern Thailand (Helicarionidae: Durgellinae). Raffles Bulletin of Zoology 66: 170 - 176. http: // doi. org / 10.5281 / zenodo. 4504598","Sutcharit C., Thach P., Chhuoy S., Ngor P. B., Jeratthitikul E., Siriwut W., Srisonchai R., Ng T. H., Pholyotha A., Jirapatrasilp P. & Panha S. 2020 c. Annotated checklist of the land snail fauna from southern Cambodia (Mollusca, Gastropoda). ZooKeys 948: 1 - 46. https: // doi. org / 10.3897 / zookeys. 948.51671","Mouhot H. 1864. Travels in the Central Parts of Indo-China (Siam), Cambodia, and Laos, During the Years 1858, 1859, and 1860. Murray, London.","Ashburton J. 1864. Paper read at the Royal Geographical Society 10 th March, 1862. In: Mouhot H. (ed.) Travels in the Central Parts of Indo-China (Siam), Cambodia, and Laos, During the Years 1858, 1859, and 1860: 296 - 300. Murray, London."]}

Genus Aenigmatoconcha Tumpeesuwan & Tumpeesuwan, 2017 Aenigmatoconcha Tumpeesuwan & Tumpeesuwan, 2017: 182–184. Aenigmatoconcha – Tumpeesuwan & Tumpeesuwan 2018: 171. Type species Aenigmatoconcha clivicola Tumpeesuwan & Tumpeesuwan, 2017, by original designation. Description Shell dextral with 5–5½ convex whorls, strongly depressed to globosely depressed, medium-sized, thin to slightly solid, translucent, and pale milky to whitish-horny in colour. Shell surface smooth, glossy, and varix usually present. Body whorl well-rounded to slightly-shouldered. Suture shallow. Aperture slightly to very crescentic in shape with simple lip. Umbilicus open and deep. Animal with reticulated skinand whitish, yellowish, pale fleshy grey to dark brown body with tiny whitish dots irregularly scattered over entire body. Mantle lobes well-developed (two shell lobes and three dorsal lobes; see Figs 3, 5A). Shell lobes can cover most, if not all of the shell and are retracted when disturbed. Left and right shell lobes very thin, translucent, ovate to triangular in shape; right shell lobe (rsl) smaller than left shell lobe (lsl). Dorsal lobes enlarged, crescent-shaped, covering body, and smaller than shell lobes. Anterior left dorsal lobe (ant-ldl) and posterior left dorsal lobe (post-ldl) smaller than right dorsal lobe (rdl). Sole tripartite, lateral foot margin, caudal fossa, and caudal horn present. Genitalia with moderately long to very long penis, thick penial sheath, short to long epiphallus, small flagellum, and short vagina. Gametolytic organ with short gametolytic duct and bulbous gametolytic sac. Oviduct with large lobules; prostate gland running alongside oviduct. Radular teeth arranged in anteriorly V-shaped or wide-angle U-shaped rows; central tooth symmetrical monocuspid and spatulate or oblong in shape; lateral and marginal teeth undifferentiated, asymmetrical monocuspid and spatulate or oblong in shape, and outermost teeth gradually reduced in size. Distribution Species of Aenigmatoconcha exhibit allopatric distributions and are restricted to limestone karsts in Thailand (Fig. 1)., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2021, Systematic revision of the limestone karst-restricted land snail genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with description of a new species, pp. 55-82 in European Journal of Taxonomy 767 on pages 62-64, DOI: 10.5852/ejt.2021.767.1487, http://zenodo.org/record/5528134, {"references":["Tumpeesuwan C. & Tumpeesuwan S. 2017. Discovery of an overlooked helicarionid land snail (Helicarionidae: Durgellinae) from northeastern Thailand, with description of a new genus and new species, and a note on radula morphology and genital system. Raffles Bulletin of Zoology 65: 174 - 181. Tumpeesuwan C. & Tumpeesuwan S. 2018. Aenigmatoconcha sumonthai, a new helicarionid land snail from Chumphon Province, Southern Thailand (Helicarionidae: Durgellinae). Raffles Bulletin of Zoology 66: 170 - 176. http: // doi. org / 10.5281 / zenodo. 4504598"]}

Aenigmatoconcha eunetis Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act: 98AD360F-93A3-4A8E-BE1A-5C991DBC358F Figs 1, 2F–H, 7E–F, 9, 10D Diagnosis Shell medium-sized and pale yellowish white. Aperture ovate-lunate in shape and vertically open. Genitalia with very long and slender penis with many tiny conical penial pilasters inside. Radular teeth arranged in wide-angle U-shaped row, teeth with oblong shape, monocuspid. Etymology The specific name ʻ eunetis ʼ is from the Greek word meaning ʻspousesʼ, honouring the authors of genus Aenigmatoconcha, who are married. Material examined Holotype THAILAND • 1 sh (width 13.9 mm, height 7.4 mm); Uthai Thani Province, Lan Sak District, Limestone outcrops at Tham Namthip Bureau of Monks; 15°26′00.3″ N, 99°35′18.7″ E; CUMZ 7931. Paratypes THAILAND • 1 sh, 7 sp; same collection data as for holotype; CUMZ 7933 • 12 sp; same collection data as for holotype; CUMZ 7932 • 2 sh; same collection data as for holotype; NHMUK. Other material THAILAND • 1 sp; Uthai Thani Province, Lan Sak District, Limestone outcrops at Hup Pa Tat; 15°22′36.5″ N, 99°37′49.5″ E; CUMZ 7934 • 6 sp; same collection data as for preceding; CUMZ 7935 • 3 sh, 27 sp; Uthai Thani Province, Nong Chang District, Limestone outcrops at Wat Khao Bang Kraek; 15°18′07.9″ N, 99°41′04.5″ E; CUMZ 7936. Description SHELL (Fig. 7E–F). Depressed to globosely depressed, medium-sized (width 12.6–14.2 mm, height 6.1– 7.1 mm), thin and translucent. Shell surface smooth, and polished, and pale yellowish white. Whorls: 5–5½, regularly increasing in size, separated by shallow suture. Spire rather elevated; varix usually present; last whorl well-rounded. Aperture very obliquely oval-lunate in shape; peristome simple. Columellar margin simple and slightly expanded near umbilicus. Umbilicus open and deep. EXTERNAL FEATURES (Fig. 2F–H). Living snails with reticulated skin and pale yellowish to slightly dark grey body. Five well-developed mantle lobes: left and right shell lobes translucent, same colour as body, covered by tiny whitish dots, right shell lobe smaller than left shell lobe. Dorsal lobes broad and crescent-shaped: right dorsal lobe larger than both anterior and posterior left dorsal lobes. Caudal fossa present; caudal horn raised and rather large, and same colour as body. GENITALIA (Fig. 9). Atrium (at) enlarged and very short. Penis (p) very long and slender with rather thick penial sheath (ps) covering from atrium to almost middle of penis. Inner sculpture of penis with small conical penial pilasters (pp), and three prominent longitudinal folds along entire length of penis chamber. Epiphallus (e1 + e2) approximately half of penis length: e1 elongate and slender, and e2 very short and bulbous. Inner sculpture of e1 nearly smooth with small, thin, and longitudinal folds, and e2 densely papillate. Epiphallic caecum (ec) straight, short, and approximately as long as e2; penial retractor muscle (prm) thin and attached at tip. Flagellum (fl) small, rather short, and approximately as long as e2. Vas deferens (vd) very long, thin, and convoluted. Vagina (v) short, enlarged, thickened and cylindrical. Gametolytic sac (gs) short and bulbous; gametolytic duct (gd) long, enlarged near vagina then becoming smaller and very slender. Free oviduct (fo) long, cylindrical, and encircled with dense tissue near vagina. RADULA (Fig. 10D). Teeth arranged in wide-angle U-shape with half row consisting of about 97–98 teeth at middle plate. Central tooth symmetrical monocuspid, elongated oblong-shaped with curved cusp, and slightly smaller than lateral tooth. Lateral and marginal teeth undifferentiated, asymmetrical monocuspid and elongated oblong-shaped with curved cusp; outermost teeth gradually becoming smaller. Distribution Aenigmatoconcha eunetis sp. nov. occurs in a few isolated limestone hills in Uthai Thani Province.This new species lives on limestone karsts, where snails tend to hide themselves in rock crevices and shelter during the daytime. Remarks Aenigmatoconcha eunetis sp. nov. clearly differs from all congeners in having 1) the longest penis, 2) penial internal sculpture consisting of longitudinal folds and small conical penial pilasters, and 3) inner sculpture of epiphallus (e2) densely papillae. For comparison, A. clivicola has oblique trapezoidshaped penial pilasters, A. mitis has oblique wrinkled penial pilasters with a longitudinal fold, and A. sumonthai has very small conical penial pilasters without longitudinal fold. In addition, for the inner sculpture of epiphallus (e2), A. clivicola has irregularly oblique trapezoid and small conical papillae. Aenigmatoconcha mitis and A. sumonthai have loose papillae arranged in oblique rows, but the former has relatively fewer rows and papillae are significantly larger in size than the latter. Moreover, radular teeth of only A. eunetis sp. nov. are arranged in wide-angle U-shaped row and oblong-shaped teeth, while radular teeth of other Aenigmatoconcha species are arranged in V-shaped rows and spatulate in shape. Discussion Each of the four Aenigmatoconcha species forms a well-defined clade in the COI phylogeny. Aenigmatoconcha can be divided into two groups based on the genital characters (Figs 1–2; Table 2). Group I (Fig. 2) has a long epiphallic caecum and short penial caecum, and contains one species, A. clivicola, which is restricted to northeasthern Thailand (Fig. 1). Group II (Fig. 2) has a short epiphallic caecum and no penial caecum; this group contains A. mitis, A. sumonthai, and A. eunetis sp. nov. This group occurs from central to southern Thailand along the Tenasserim Range (Fig. 1). The COI tree showed very low nodal support for the relationships among the two Aenigmatoconcha groups and the other two helicarionid genera. Although the phylogenetic relationships among Aenigmatoconcha, Sophina and Chalepotaxis remain unresolved, the genital characters of both groups of Aenigmatoconcha were clearly distinct from Sophina and Chalepotaxis. In the phylogenetic tree of the 28S gene, moreover, these three genera were confirmed as different genera, but the systematic position of two Aenigmatoconcha species (A. clivicola and A. sumonthai) is unresolved (Sutcharit et al. 2020a). Further research should include on more genes and more taxa of the Southeast Asian helicarionoids to better understand the phylogenetic relationships and morphological evolution of these groups. Aenigmatoconcha can be distinguished from almost all other Southeast Asian helicarionoid genera by their unique milky to pale whitish-horny and umbilicate shell. Other helicarionoids with a whitish shell include Macrochlamys psyche Vermeulen et al., 2019, Sarika lactoconcha Pholyotha & Panha, 2020, and Sarika consepta (Benson, 1860). However, the relatively medium to large-sized shells (shell width larger than 15 mm), narrowly perforate umbilicus, genital structure, and radula with triangular teeth of these three species clearly differentiate them from all Aenigmatoconcha species (Vermeulen et al. 2019; Pholyotha et al. 2020 a, 2020b). The greatest similarity in shell characters occurred in Sophina and Chalepotaxis, but their genitalia are obviously different. The distinctive characters between Aenigmatoconcha and Chalepotaxis have been reported (Tumpeesuwan & Tumpeesuwan 2017; Sutcharit et al. 2020a). However, Tumpeesuwan and Tumpeesuwan (2017) did not report the presence of a “penial sheath” and a “flagellum” in A. clivicola (the type species). In fact, they stated that the absence of a penial sheath in Aenigmatoconcha is a diagnostic difference between Aenigmatoconcha and Chalepotaxis. Yet, in the present work, the four Aenigmatoconcha species clearly exhibited a well-developed penial sheath and flagellum. Hence, the only difference between Chalepotaxis and Aenigmatoconcha is the presence of a flagellum in the latter (Páll-Gergely et al. 2016). In addition to the genitalia without a dart apparatus, the presence of well-developed anterior and posterior left dorsal lobes is a significant character of Aenigmatoconcha, while Sophina has an undivided left dorsal lobe and a dart apparatus (Blanford & Godwin-Austen 1908; Sutcharit et al. 2020a). However, information on the mantle lobe morphology of Chalepotaxis was not available for comparison. Among Southeast Asian helicarionoid genera with uniform and spatulate-shaped radula, Sophina is the only genus that a dart apparatus present in genitalia, but a flagellum absent. While genitalia of Aenigmatoconcha lack dart apparatus, but contain the flagellum, and genitalia of Chalepotaxis lack both organs. Generally, some characters of genital anatomy, such as a penial caecum, penial verge, dart apparatus, or flagellum, have been hypothesized to evolve repeatedly during the evolution of land snails, and have been noticed in many groups of terrestrial pulmonate snails (Solem 1966; Hausdorf 1998; Hyman & Ponder 2010; Hirano et al. 2014; Köhler & Criscione 2015; Köhler et al. 2020; Sutcharit et al. 2020a). However, the classification of these three genera based on the presence or absence of the dart apparatus and flagellum is consistent with the molecular phylogeny (Sutcharit et al. 2020a). From the East of Tenasserim Range to northeastern Thailand, three Aenigmatoconcha species occurred in a few limestone karsts, while only A. mitis occurs in many limestone karsts from central to western Thailand (Fig. 1). Aenigmatoconcha clivicola is confined to Loei Province, northeastern Thailand, while A. eunetis sp. nov. to Uthai Thani Province, central Thailand, and A. sumonthai to Chumphon Province, southern Thailand. The isolation explains the degree of endemism and the very high genetic divergence among sister lineages (9.7% to 12.0%) within Aenigmatoconcha. Regarding the West of Tenasserim Range, Sophina also reveals a high degree of endemism and localization with a pattern of one outcrop for one lineage in the Salween Basin, Southern Myanmar. These phenomena can be generally observed in karst-restricted animals because a very large number of ecological niches in karst ecosystems promote their evolutionary diversification and evolution of remarkably different lifestyles (Clements et al. 2006; Foon et al. 2017; Grismer et al. 2020; Sutcharit et al. 2020a). Therefore, our discovery enhances the understanding of karst biodiversity and supplements the information on terrestrial snails in Thailand available for efforts to establish well-planned and knowledge-based conservation procedures for Thai limestone protection in the future.

Genus Aenigmatoconcha Tumpeesuwan & Tumpeesuwan, 2017 Aenigmatoconcha Tumpeesuwan & Tumpeesuwan, 2017: 182–184. Aenigmatoconcha – Tumpeesuwan & Tumpeesuwan 2018: 171. Type species Aenigmatoconcha clivicola Tumpeesuwan & Tumpeesuwan, 2017, by original designation. Description Shell dextral with 5–5½ convex whorls, strongly depressed to globosely depressed, medium-sized, thin to slightly solid, translucent, and pale milky to whitish-horny in colour. Shell surface smooth, glossy, and varix usually present. Body whorl well-rounded to slightly-shouldered. Suture shallow. Aperture slightly to very crescentic in shape with simple lip. Umbilicus open and deep. Animal with reticulated skinand whitish, yellowish, pale fleshy grey to dark brown body with tiny whitish dots irregularly scattered over entire body. Mantle lobes well-developed (two shell lobes and three dorsal lobes; see Figs 3, 5A). Shell lobes can cover most, if not all of the shell and are retracted when disturbed. Left and right shell lobes very thin, translucent, ovate to triangular in shape; right shell lobe (rsl) smaller than left shell lobe (lsl). Dorsal lobes enlarged, crescent-shaped, covering body, and smaller than shell lobes. Anterior left dorsal lobe (ant-ldl) and posterior left dorsal lobe (post-ldl) smaller than right dorsal lobe (rdl). Sole tripartite, lateral foot margin, caudal fossa, and caudal horn present. Genitalia with moderately long to very long penis, thick penial sheath, short to long epiphallus, small flagellum, and short vagina. Gametolytic organ with short gametolytic duct and bulbous gametolytic sac. Oviduct with large lobules; prostate gland running alongside oviduct. Radular teeth arranged in anteriorly V-shaped or wide-angle U-shaped rows; central tooth symmetrical monocuspid and spatulate or oblong in shape; lateral and marginal teeth undifferentiated, asymmetrical monocuspid and spatulate or oblong in shape, and outermost teeth gradually reduced in size. Distribution Species of Aenigmatoconcha exhibit allopatric distributions and are restricted to limestone karsts in Thailand (Fig. 1).

Aenigmatoconcha sumonthai Tumpeesuwan & Tumpeesuwan, 2018 Figs 1, 2C–E, 7A–D, 8, 10C Aenigmatoconcha sumonthai Tumpeesuwan & Tumpeesuwan, 2018: 171–173, figs 2–6. Type locality: Tham Chang Phueak limestone range, Mueang District, Chumphon Province, southern Thailand. Material examined THAILAND • 45 sh, 20 sp; Chumphon Province, Mueang District, Limestone outcrops at Tham Chang Phuek Bureau of Monks; 10°26′50.0″ N, 99°02′07.1″ E; CUMZ 7922 • 40 sh; same collection data as for preceding; CUMZ 7923 • 18 sh, 10 sp; same collection data as for preceding; CUMZ 7937 • 45 sh, 6 sp; Chumphon Province, Mueang District, Limestone outcrops at Wat Tham Sanook; 10°28′51.3″ N, 99°04′28.3″ E; CUMZ 7924 • 10 sh, 7 sp; same collection data as for preceding; CUMZ 7925 • 22 sh, 11 sp; Chumphon Province, Sawi District, Limestone outcrops at Tham Nam Lod Thepnimit Bureau of Monks; 10°22′39.5″ N, 99°00′39.5″ E; CUMZ 7927 • 4 sh, 8 sp; Chumphon Province, Sawi District, Limestone outcrops at Wat Nam Cha; 10°17′57.0″ N, 99°01′58.5″ E; CUMZ 7926. Description SHELL (Fig. 7A–B). Shell strongly depressed to depressed, medium-sized (width 14.4–16.6 mm, height 7.0– 8.2 mm), thin, translucent, whitish colour, well-rounded to slightly shouldered body whorl, elevated spire, impressed suture, obvious varix, and open umbilicus. EXTERNAL FEATURES (Fig. 2C–E). Animal with five well-developed mantle lobes. Left and right shell lobes pale yellowish to fleshy-grey colour, usually with black margin, and with or without small to large black spots or blotches. Three dorsal lobes crescent-shaped and smaller than the other two shell lobes. Black stripes behind long tentacles. GENITALIA (Fig. 8). Atrium (at) enlarged and very short. Penis (p) long, cylindrical with thick penial sheath (ps) extending to half of penis length. Inner sculpture of penis with small conical penial pilasters (pp). Epiphallus (e1 + e2) as long as penis: e1 slender, and e2 bulbous. Inner sculpture of e1 with small thin longitudinal folds, while e2 with small papillae arranged in oblique rows. Epiphallic caecum (ec) short with thin penial retractor muscle (prm) attached at tip. Flagellum (fl) small and short. RADULA (Fig. 10C). Teeth arranged in anteriorly V-shaped rows with half row consisting of about 63– 65 teeth at the middle plate. All teeth monocuspid and spatulate-shaped with curved cusp. Distribution Aenigmatoconcha sumonthai has a narrow distribution, with populations living on a few limestone hills in Chumphon Province (Fig. 1). We extended our survey, especially among limestone sites about 200 km southwards down to southern peninsular Thailand, but we could not find this species elsewhere. Remarks The lack of a penial sheath and flagellum in the male reproductive organs of A. sumonthai was originally reported to be similar to A. clivicola (Tumpeesuwan & Tumpeesuwan, 2018: 174, fig. 6). In this study, based on topotypic specimens, however, A. sumonthai was found to have a large and thickened penial sheath and small flagellum encircled with loose tissue (Fig. 8). Aenigmatoconcha sumonthai shows variation in the black blotches on both shell lobes ranging from absent (Fig. 2E) to the lobes almost entirely covered (Fig. 2C). The DNA sequence analysis suggested that these variations formed a clade of A. sumonthai (Fig. 2). In addition, this species develops a calcareous epiphragm with a small perforation to limit body-water evaporation but allowing respiratory gas exchange during dormancy (Fig. 7C, D).

Aenigmatoconcha clivicola Tumpeesuwan & Tumpeesuwan, 2017 Figs 1, 2A, 4A–B, 5, 10A Aenigmatoconcha clivicola Tumpeesuwan & Tumpeesuwan, 2017: 184–187, figs 2–5. Type locality: Phu Pha Lom Limestone Hill in Mueang District, Loei Province, northeastern Thailand. Aenigmatoconcha clivicola – Tumpeesuwan & Tumpeesuwan 2018: 171. Material examined THAILAND • 39 sh, 22 sp; Loei Province, Mueang District, Phu Pha Lom Limestone Hill; 17°33′16.6″ N, 101°52′05.4″ E; CUMZ 7928 • 6 sh, 12 sp; same collection data as for preceding; CUMZ 7929 • 48 sh; Loei Province, Na Duang District, Limestone outcrops at Wat Tham Pha Ya; 17°34′40.1″ N, 101°53′35.1″ E; CUMZ 7930. Description SHELL (Fig. 4A–B). Shell strongly depressed to depressed, medium-sized (shell width 17.2–20.1 mm, shell height 8.6–10.0 mm), rather thin to slightly solid and translucent, milky to pale whitish-horny colour, well-rounded body whorl, little elevated spire, impressed suture, obvious varix, and open umbilicus. EXTERNAL FEATURES (Figs 2A, 5A). Animal with five well-developed mantle lobes. Left and right shell lobes thin, pale yellowish to fleshy-grey colour and spread with small whitish dots. Three dorsal lobes crescent-shaped and smaller than shell lobes. GENITALIA (Fig. 5B–D). Atrium (at) enlarged and very short. Penis (p) rather long cylindrical, penial sheath (ps) very thick and covering entire penis, and penial caecum (pc) rather small protruding. Inner wall of penis covered with trapezoid-shaped penial pilasters (pp) arranged in oblique rows. Epiphallus (e1 + e2) as long as penis: e1 long and slender, and e2 bulbous and about half e1 length. Inner sculpture of e1 with very small and thin longitudinal folds to nearly smooth surface. Inner sculpture of e2 trapezoid to conical pilasters. Epiphallic caecum (ec) long with thick penial retractor muscle (prm) attached at tip. Flagellum (fl) small and short. RADULA (Fig. 10A). Teeth arranged in anteriorly V-shaped rows with half row consisting of about 70– 76 teeth at middle plate. Central, lateral, and marginal teeth monocuspid and spatulate-shaped with curved cusp. Distribution This species is currently known only from 2 localities: the type locality (Phu Pha Lom) and limestone hills in Loei Province (Fig. 1). Remarks The genitalia were originally described but without examination of the internal sculpture of penis. In this study, we examined 20 adult topotypic specimens to provide descriptions of the penial sheath, penial caecum, and flagellum that were not included in the original description. The penial sheath is very large and covers the entire penis (Fig. 5B). The short penial caecum, an extension of the penis, is located near the penis and epiphallus junction (Fig. 5B). This character is visible when penial sheath is removed. Its internal sculpture is rather smooth, unlike the penial sculpture, with its trapezoid-shaped pilasters (Fig. 5C). The Australian helicarionids, Nitor whitneyae Stanisic, 2010 has a penial caecum while other Nitor taxa do not have a penial caecum (Hyman & Köhler 2018). In Southeast Asian ariophantids, the presence or absence of a penial caecum is a discriminating character among species in genera such as Macrochlamys Gray, 1847 and Taphrenalla Pholyotha & Panha, 2020, and is supported by molecular studies (Pholyotha et al. 2018, 2021). The flagellum of A. clivicola is an extension of the epiphallus and is located near the insertion point of the vas deferens. It is somewhat small and short, and bound to the vas deferens by thin connective tissue. This feature is important for spermatophore formation before copulation (Tompa 1984; Baur 2010). However, during this study no spermatophores were observed in A. clivicola., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2021, Systematic revision of the limestone karst-restricted land snail genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with description of a new species, pp. 55-82 in European Journal of Taxonomy 767 on pages 64-66, DOI: 10.5852/ejt.2021.767.1487, http://zenodo.org/record/5528134, {"references":["Tumpeesuwan C. & Tumpeesuwan S. 2017. Discovery of an overlooked helicarionid land snail (Helicarionidae: Durgellinae) from northeastern Thailand, with description of a new genus and new species, and a note on radula morphology and genital system. Raffles Bulletin of Zoology 65: 174 - 181. Tumpeesuwan C. & Tumpeesuwan S. 2018. Aenigmatoconcha sumonthai, a new helicarionid land snail from Chumphon Province, Southern Thailand (Helicarionidae: Durgellinae). Raffles Bulletin of Zoology 66: 170 - 176. http: // doi. org / 10.5281 / zenodo. 4504598","Pfeiffer L. 1863. Descriptions of thirty-six new land shells from the collection of H. Cuming, Esq. Proceedings of the Zoological Society of London 30: 268 - 278. [Published in parts, dates follow Duncan (1937)].","Pholyotha A., Sutcharit C., Tongkerd P. & Panha S. 2020 b. Integrative taxonomic revision of the land snail genus Sarika Godwin-Austen, 1907 in Thailand, with descriptions of nine new species (Eupulmonata, Ariophantidae). ZooKeys 976: 1 - 100. https: // doi. org / 10.3897 / zookeys. 976.53859","Pholyotha A., Sutcharit C. & Panha S. 2018. The land snail genus Macrochlamys Gray, 1847 from Thailand, with descriptions of five new species (Pulmonata: Ariophantidae). Raffles Bulletin of Zoology 66: 763 - 781.","Pholyotha A., Sutcharit C., Tongkerd P., Jeratthitikul E. & Panha S. 2021. Integrative systematics reveals the new land-snail genus Taphrenalla (Eupulmonata: Ariophantidae) with a description of nine new species from Thailand. Contributions to Zoology 90 (1): 21 - 69. https: // doi. org / 10.1163 / 18759866 - BJA 10013","Tompa A. S. 1984. Land snails (Stylommatophora). In: Tompa A. S. & Verdonk N. H. (eds) The Mollusca, Vol. 7: Reproduction: 47 - 140. Academic Press, London.","Baur B. 2010. Stylommatophoran Gastropods. In: Leonard J. L. & Cordoba-Aguilar A. (eds) The Evolution of Primary Sexual Characters in Animals: 197 - 217. Oxford University Press, USA."]}

Aenigmatoconcha eunetis Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act: 98AD360F-93A3-4A8E-BE1A-5C991DBC358F Figs 1, 2F–H, 7E–F, 9, 10D Diagnosis Shell medium-sized and pale yellowish white. Aperture ovate-lunate in shape and vertically open. Genitalia with very long and slender penis with many tiny conical penial pilasters inside. Radular teeth arranged in wide-angle U-shaped row, teeth with oblong shape, monocuspid. Etymology The specific name ʻ eunetis ʼ is from the Greek word meaning ʻspousesʼ, honouring the authors of genus Aenigmatoconcha, who are married. Material examined Holotype THAILAND • 1 sh (width 13.9 mm, height 7.4 mm); Uthai Thani Province, Lan Sak District, Limestone outcrops at Tham Namthip Bureau of Monks; 15°26′00.3″ N, 99°35′18.7″ E; CUMZ 7931. Paratypes THAILAND • 1 sh, 7 sp; same collection data as for holotype; CUMZ 7933 • 12 sp; same collection data as for holotype; CUMZ 7932 • 2 sh; same collection data as for holotype; NHMUK. Other material THAILAND • 1 sp; Uthai Thani Province, Lan Sak District, Limestone outcrops at Hup Pa Tat; 15°22′36.5″ N, 99°37′49.5″ E; CUMZ 7934 • 6 sp; same collection data as for preceding; CUMZ 7935 • 3 sh, 27 sp; Uthai Thani Province, Nong Chang District, Limestone outcrops at Wat Khao Bang Kraek; 15°18′07.9″ N, 99°41′04.5″ E; CUMZ 7936. Description SHELL (Fig. 7E–F). Depressed to globosely depressed, medium-sized (width 12.6–14.2 mm, height 6.1– 7.1 mm), thin and translucent. Shell surface smooth, and polished, and pale yellowish white. Whorls: 5–5½, regularly increasing in size, separated by shallow suture. Spire rather elevated; varix usually present; last whorl well-rounded. Aperture very obliquely oval-lunate in shape; peristome simple. Columellar margin simple and slightly expanded near umbilicus. Umbilicus open and deep. EXTERNAL FEATURES (Fig. 2F–H). Living snails with reticulated skin and pale yellowish to slightly dark grey body. Five well-developed mantle lobes: left and right shell lobes translucent, same colour as body, covered by tiny whitish dots, right shell lobe smaller than left shell lobe. Dorsal lobes broad and crescent-shaped: right dorsal lobe larger than both anterior and posterior left dorsal lobes. Caudal fossa present; caudal horn raised and rather large, and same colour as body. GENITALIA (Fig. 9). Atrium (at) enlarged and very short. Penis (p) very long and slender with rather thick penial sheath (ps) covering from atrium to almost middle of penis. Inner sculpture of penis with small conical penial pilasters (pp), and three prominent longitudinal folds along entire length of penis chamber. Epiphallus (e1 + e2) approximately half of penis length: e1 elongate and slender, and e2 very short and bulbous. Inner sculpture of e1 nearly smooth with small, thin, and longitudinal folds, and e2 densely papillate. Epiphallic caecum (ec) straight, short, and approximately as long as e2; penial retractor muscle (prm) thin and attached at tip. Flagellum (fl) small, rather short, and approximately as long as e2. Vas deferens (vd) very long, thin, and convoluted. Vagina (v) short, enlarged, thickened and cylindrical. Gametolytic sac (gs) short and bulbous; gametolytic duct (gd) long, enlarged near vagina then becoming smaller and very slender. Free oviduct (fo) long, cylindrical, and encircled with dense tissue near vagina. RADULA (Fig. 10D). Teeth arranged in wide-angle U-shape with half row consisting of about 97–98 teeth at middle plate. Central tooth symmetrical monocuspid, elongated oblong-shaped with curved cusp, and slightly smaller than lateral tooth. Lateral and marginal teeth undifferentiated, asymmetrical monocuspid and elongated oblong-shaped with curved cusp; outermost teeth gradually becoming smaller. Distribution Aenigmatoconcha eunetis sp. nov. occurs in a few isolated limestone hills in Uthai Thani Province.This new species lives on limestone karsts, where snails tend to hide themselves in rock crevices and shelter during the daytime. Remarks Aenigmatoconcha eunetis sp. nov. clearly differs from all congeners in having 1) the longest penis, 2) penial internal sculpture consisting of longitudinal folds and small conical penial pilasters, and 3) inner sculpture of epiphallus (e2) densely papillae. For comparison, A. clivicola has oblique trapezoidshaped penial pilasters, A. mitis has oblique wrinkled penial pilasters with a longitudinal fold, and A. sumonthai has very small conical penial pilasters without longitudinal fold. In addition, for the inner sculpture of epiphallus (e2), A. clivicola has irregularly oblique trapezoid and small conical papillae. Aenigmatoconcha mitis and A. sumonthai have loose papillae arranged in oblique rows, but the former has relatively fewer rows and papillae are significantly larger in size than the latter. Moreover, radular teeth of only A. eunetis sp. nov. are arranged in wide-angle U-shaped row and oblong-shaped teeth, while radular teeth of other Aenigmatoconcha species are arranged in V-shaped rows and spatulate in shape. Discussion Each of the four Aenigmatoconcha species forms a well-defined clade in the COI phylogeny. Aenigmatoconcha can be divided into two groups based on the genital characters (Figs 1–2; Table 2). Group I (Fig. 2) has a long epiphallic caecum and short penial caecum, and contains one species, A. clivicola, which is restricted to northeasthern Thailand (Fig. 1). Group II (Fig. 2) has a short epiphallic caecum and no penial caecum; this group contains A. mitis, A. sumonthai, and A. eunetis sp. nov. This group occurs from central to southern Thailand along the Tenasserim Range (Fig. 1). The COI tree showed very low nodal support for the relationships among the two Aenigmatoconcha groups and the other two helicarionid genera. Although the phylogenetic relationships among Aenigmatoconcha, Sophina and Chalepotaxis remain unresolved, the genital characters of both groups of Aenigmatoconcha were clearly distinct from Sophina and Chalepotaxis. In the phylogenetic tree of the 28S gene, moreover, these three genera were confirmed as different genera, but the systematic position of two Aenigmatoconcha species (A. clivicola and A. sumonthai) is unresolved (Sutcharit et al. 2020a). Further research should include on more genes and more taxa of the Southeast Asian helicarionoids to better understand the phylogenetic relationships and morphological evolution of these groups. Aenigmatoconcha can be distinguished from almost all other Southeast Asian helicarionoid genera by their unique milky to pale whitish-horny and umbilicate shell. Other helicarionoids with a whitish shell include Macrochlamys psyche Vermeulen et al., 2019, Sarika lactoconcha Pholyotha & Panha, 2020, and Sarika consepta (Benson, 1860). However, the relatively medium to large-sized shells (shell width larger than 15 mm), narrowly perforate umbilicus, genital structure, and radula with triangular teeth of these three species clearly differentiate them from all Aenigmatoconcha species (Vermeulen et al. 2019; Pholyotha et al. 2020 a, 2020b). The greatest similarity in shell characters occurred in Sophina and Chalepotaxis, but their genitalia are obviously different. The distinctive characters between Aenigmatoconcha and Chalepotaxis have been reported (Tumpeesuwan & Tumpeesuwan 2017; Sutcharit et al. 2020a). However, Tumpeesuwan and Tumpeesuwan (2017) did not report the presence of a “penial sheath” and a “flagellum” in A. clivicola (the type species). In fact, they stated that the absence of a penial sheath in Aenigmatoconcha is a diagnostic difference between Aenigmatoconcha and Chalepotaxis. Yet, in the present work, the four Aenigmatoconcha species clearly exhibited a well-developed penial sheath and flagellum. Hence, the only difference between Chalepotaxis and Aenigmatoconcha is the presence of a flagellum in the latter (Páll-Gergely et al. 2016). In addition to the genitalia without a dart apparatus, the presence of well-developed anterior and posterior left dorsal lobes is a significant character of Aenigmatoconcha, while Sophina has an undivided left dorsal lobe and a dart apparatus (Blanford & Godwin-Austen 1908; Sutcharit et al. 2020a). However, information on the mantle lobe morphology of Chalepotaxis was not available for comparison. Among Southeast Asian helicarionoid genera with uniform and spatulate-shaped radula, Sophina is the only genus that a dart apparatus present in genitalia, but a flagellum absent. While genitalia of Aenigmatoconcha lack dart apparatus, but contain the flagellum, and genitalia of Chalepotaxis lack both organs. Generally, some characters of genital anatomy, such as a penial caecum, penial verge, dart apparatus, or flagellum, have been hypothesized to evolve repeatedly during the evolution of land snails, and have been noticed in many groups of terrestrial pulmonate snails (Solem 1966; Hausdorf 1998; Hyman & Ponder 2010; Hirano et al. 2014; Köhler & Criscione 2015; Köhler et al. 2020; Sutcharit et al. 2020a). However, the classification of these three genera based on the presence or absence of the dart apparatus and flagellum is consistent with the molecular phylogeny (Sutcharit et al. 2020a). From the East of Tenasserim Range to northeastern Thailand, three Aenigmatoconcha species occurred in a few limestone karsts, while only A. mitis occurs in many limestone karsts from central to western Thailand (Fig. 1). Aenigmatoconcha clivicola is confined to Loei Province, northeastern Thailand, while A. eunetis sp. nov. to Uthai Thani Province, central Thailand, and A. sumonthai to Chumphon Province, southern Thailand. The isolation explains the degree of endemism and the very high genetic divergence among sister lineages (9.7% to 12.0%) within Aenigmatoconcha. Regarding the West of Tenasserim Range, Sophina also reveals a high degree of endemism and localization with a pattern of one outcrop for one lineage in the Salween Basin, Southern Myanmar. These phenomena can be generally observed in karst-restricted animals because a very large number of ecological niches in karst ecosystems promote their evolutionary diversification and evolution of remarkably different lifestyles (Clements et al. 2006; Foon et al. 2017; Grismer et al. 2020; Sutcharit et al. 2020a). Therefore, our discovery enhances the understanding of karst biodiversity and supplements the information on terrestrial snails in Thailand available for efforts to establish well-planned and knowledge-based conservation procedures for Thai limestone protection in the future., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2021, Systematic revision of the limestone karst-restricted land snail genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with description of a new species, pp. 55-82 in European Journal of Taxonomy 767 on pages 72-77, DOI: 10.5852/ejt.2021.767.1487, http://zenodo.org/record/5528134, {"references":["Sutcharit C., Jeratthitikul E., Pholyotha A., Lin A. & Panha S. 2020 a. Molecular phylogeny reveals high diversity and endemism in the limestone karst-restricted land snail genus Sophina Benson, 1859 from Myanmar (Eupulmonata: Helicarionidae), with description of four new species. Journal of Zoological Systematics and Evolutionary Research 58: 957 - 981. https: // doi. org / 10.1111 / jzs. 12420","Vermeulen J. J., Luu H. T., Theary K. & Anker K. 2019. New species of land snails (Mollusca: Gastropoda: Caenogastropoda and Pulmonata) of the Mekong Delta Limestone Hills (Cambodia, Vietnam). Folia Malacologica 27: 7 - 41. https: // doi. org / 10.12657 / folmal. 027.001","Pholyotha A., Sutcharit C., Tongkerd P. & Panha S. 2020 b. Integrative taxonomic revision of the land snail genus Sarika Godwin-Austen, 1907 in Thailand, with descriptions of nine new species (Eupulmonata, Ariophantidae). ZooKeys 976: 1 - 100. https: // doi. org / 10.3897 / zookeys. 976.53859","Pholyotha A., Sutcharit C., Thach P., Chhuoy S., Ngor P. B. & Panha S. 2020 a. Land snail genus Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Cambodia, with description of three new species. European Journal of Taxonomy 674: 1 - 21. https: // doi. org / 10.5852 / ejt. 2020.674","Tumpeesuwan C. & Tumpeesuwan S. 2017. Discovery of an overlooked helicarionid land snail (Helicarionidae: Durgellinae) from northeastern Thailand, with description of a new genus and new species, and a note on radula morphology and genital system. Raffles Bulletin of Zoology 65: 174 - 181. Tumpeesuwan C. & Tumpeesuwan S. 2018. Aenigmatoconcha sumonthai, a new helicarionid land snail from Chumphon Province, Southern Thailand (Helicarionidae: Durgellinae). Raffles Bulletin of Zoology 66: 170 - 176. http: // doi. org / 10.5281 / zenodo. 4504598","Pall-Gergely B., Feher Z., Otani J. U. & Asami T. 2016. An integrative taxonomic approach to infer the systematic position of Chalepotaxis Ancey, 1887 (Gastropoda: Stylommatophora: Helicarionidae). Molluscan Research 37: 113 - 119. https: // doi. org / 10.1080 / 13235818.2016.1234996","Pfeiffer L. 1863. Descriptions of thirty-six new land shells from the collection of H. Cuming, Esq. Proceedings of the Zoological Society of London 30: 268 - 278. [Published in parts, dates follow Duncan (1937)].","Solem A. 1966. Some non-marine mollusks from Thailand, with notes on classification of the Helicarionidae. Spolia Zoologica Musei Hauniensis 24: 1 - 110.","Hausdorf B. 1998. Phylogeny of the Limacoidea sensu lato (Gastropoda: Stylommatophora). Journal of Molluscan Studies 64: 35 - 66. https: // doi. org / 10.1093 / mollus / 64.1.35","Hyman I. T. & Ponder W. F. 2010. A morphological phylogenetic analysis and generic revision of Australian Helicarionidae (Gastropoda: Pulmonata: Stylommatophora), and an assessment of the relationships of the family. Zootaxa 2462: 1 - 148. http: // doi. org / 10.11646 / zootaxa. 2462.1.1","Hirano T., Kameda Y., Kimura K. & Chiba S. 2014. Substantial incongruence among the morphology, taxonomy, and molecular phylogeny of the land snails Aegista, Landouria, Trishoplita, and Pseudobuliminus (Pulmonata: Bradybaenidae) occurring in East Asia. Molecular Phylogenetics and Evolution 70: 171 - 181. https: // doi. org / 10.1016 / j. ympev. 2013.09.020","Kohler F. & Criscione F. 2015. A molecular phylogeny of camaenid land snails from northwestern Australia unravels widespread homoplasy in morphological characters (Gastropoda, Helicoidea). Molecular Phylogenetics and Evolution 83: 44 - 55. https: // doi. org / 10.1016 / j. ympev. 2014.11.009","Kohler F., Criscione F. & Shea M. 2020. A mitochondrial phylogeny uncovers taxonomic ambiguity and complex phylogeographic patterns in the eastern Australian land snail Austrochloritis (Stylommatophora, Camaenidae). Journal of Zoological Systematics and Evolutionary Research 58: 1005 - 1020. https: // doi. org / 10.1111 / jzs. 12366","Clements R., Sodhi N. S., Schilthuizen M. & Ng P. K. 2006. Limestone karsts of Southeast Asia: Imperiled arks of biodiversity. Bioscience 56 (9): 733 - 742. https: // doi. org / fq 9 mjv","Foon J. K., Clements G. R. & Liew T. - S. 2017. Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia. ZooKeys 682: 1 - 94. https: // doi. org / 10.3897 / zookeys. 682.12999","Grismer L. L., Wood P. L., Le M. D., Quah E. S. H. & Grismer J. L. 2020. Evolution of habitat preference in 243 species of Bent-toed geckos (Genus Cyrtodactylus Gray, 1827) with a discussion of karst habitat conservation. Ecology and Evolution 10: 13717 - 13730. https: // doi. org / 10.1002 / ece 3.6961"]}

Aenigmatoconcha sumonthai Tumpeesuwan & Tumpeesuwan, 2018 Figs 1, 2C–E, 7A–D, 8, 10C Aenigmatoconcha sumonthai Tumpeesuwan & Tumpeesuwan, 2018: 171–173, figs 2–6. Type locality: Tham Chang Phueak limestone range, Mueang District, Chumphon Province, southern Thailand. Material examined THAILAND • 45 sh, 20 sp; Chumphon Province, Mueang District, Limestone outcrops at Tham Chang Phuek Bureau of Monks; 10°26′50.0″ N, 99°02′07.1″ E; CUMZ 7922 • 40 sh; same collection data as for preceding; CUMZ 7923 • 18 sh, 10 sp; same collection data as for preceding; CUMZ 7937 • 45 sh, 6 sp; Chumphon Province, Mueang District, Limestone outcrops at Wat Tham Sanook; 10°28′51.3″ N, 99°04′28.3″ E; CUMZ 7924 • 10 sh, 7 sp; same collection data as for preceding; CUMZ 7925 • 22 sh, 11 sp; Chumphon Province, Sawi District, Limestone outcrops at Tham Nam Lod Thepnimit Bureau of Monks; 10°22′39.5″ N, 99°00′39.5″ E; CUMZ 7927 • 4 sh, 8 sp; Chumphon Province, Sawi District, Limestone outcrops at Wat Nam Cha; 10°17′57.0″ N, 99°01′58.5″ E; CUMZ 7926. Description SHELL (Fig. 7A–B). Shell strongly depressed to depressed, medium-sized (width 14.4–16.6 mm, height 7.0– 8.2 mm), thin, translucent, whitish colour, well-rounded to slightly shouldered body whorl, elevated spire, impressed suture, obvious varix, and open umbilicus. EXTERNAL FEATURES (Fig. 2C–E). Animal with five well-developed mantle lobes. Left and right shell lobes pale yellowish to fleshy-grey colour, usually with black margin, and with or without small to large black spots or blotches. Three dorsal lobes crescent-shaped and smaller than the other two shell lobes. Black stripes behind long tentacles. GENITALIA (Fig. 8). Atrium (at) enlarged and very short. Penis (p) long, cylindrical with thick penial sheath (ps) extending to half of penis length. Inner sculpture of penis with small conical penial pilasters (pp). Epiphallus (e1 + e2) as long as penis: e1 slender, and e2 bulbous. Inner sculpture of e1 with small thin longitudinal folds, while e2 with small papillae arranged in oblique rows. Epiphallic caecum (ec) short with thin penial retractor muscle (prm) attached at tip. Flagellum (fl) small and short. RADULA (Fig. 10C). Teeth arranged in anteriorly V-shaped rows with half row consisting of about 63– 65 teeth at the middle plate. All teeth monocuspid and spatulate-shaped with curved cusp. Distribution Aenigmatoconcha sumonthai has a narrow distribution, with populations living on a few limestone hills in Chumphon Province (Fig. 1). We extended our survey, especially among limestone sites about 200 km southwards down to southern peninsular Thailand, but we could not find this species elsewhere. Remarks The lack of a penial sheath and flagellum in the male reproductive organs of A. sumonthai was originally reported to be similar to A. clivicola (Tumpeesuwan & Tumpeesuwan, 2018: 174, fig. 6). In this study, based on topotypic specimens, however, A. sumonthai was found to have a large and thickened penial sheath and small flagellum encircled with loose tissue (Fig. 8). Aenigmatoconcha sumonthai shows variation in the black blotches on both shell lobes ranging from absent (Fig. 2E) to the lobes almost entirely covered (Fig. 2C). The DNA sequence analysis suggested that these variations formed a clade of A. sumonthai (Fig. 2). In addition, this species develops a calcareous epiphragm with a small perforation to limit body-water evaporation but allowing respiratory gas exchange during dormancy (Fig. 7C, D)., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2021, Systematic revision of the limestone karst-restricted land snail genus Aenigmatoconcha (Eupulmonata: Helicarionidae), with description of a new species, pp. 55-82 in European Journal of Taxonomy 767 on pages 70-72, DOI: 10.5852/ejt.2021.767.1487, http://zenodo.org/record/5528134

Aenigmatoconcha clivicola Tumpeesuwan & Tumpeesuwan, 2017 Figs 1, 2A, 4A–B, 5, 10A Aenigmatoconcha clivicola Tumpeesuwan & Tumpeesuwan, 2017: 184–187, figs 2–5. Type locality: Phu Pha Lom Limestone Hill in Mueang District, Loei Province, northeastern Thailand. Aenigmatoconcha clivicola – Tumpeesuwan & Tumpeesuwan 2018: 171. Material examined THAILAND • 39 sh, 22 sp; Loei Province, Mueang District, Phu Pha Lom Limestone Hill; 17°33′16.6″ N, 101°52′05.4″ E; CUMZ 7928 • 6 sh, 12 sp; same collection data as for preceding; CUMZ 7929 • 48 sh; Loei Province, Na Duang District, Limestone outcrops at Wat Tham Pha Ya; 17°34′40.1″ N, 101°53′35.1″ E; CUMZ 7930. Description SHELL (Fig. 4A–B). Shell strongly depressed to depressed, medium-sized (shell width 17.2–20.1 mm, shell height 8.6–10.0 mm), rather thin to slightly solid and translucent, milky to pale whitish-horny colour, well-rounded body whorl, little elevated spire, impressed suture, obvious varix, and open umbilicus. EXTERNAL FEATURES (Figs 2A, 5A). Animal with five well-developed mantle lobes. Left and right shell lobes thin, pale yellowish to fleshy-grey colour and spread with small whitish dots. Three dorsal lobes crescent-shaped and smaller than shell lobes. GENITALIA (Fig. 5B–D). Atrium (at) enlarged and very short. Penis (p) rather long cylindrical, penial sheath (ps) very thick and covering entire penis, and penial caecum (pc) rather small protruding. Inner wall of penis covered with trapezoid-shaped penial pilasters (pp) arranged in oblique rows. Epiphallus (e1 + e2) as long as penis: e1 long and slender, and e2 bulbous and about half e1 length. Inner sculpture of e1 with very small and thin longitudinal folds to nearly smooth surface. Inner sculpture of e2 trapezoid to conical pilasters. Epiphallic caecum (ec) long with thick penial retractor muscle (prm) attached at tip. Flagellum (fl) small and short. RADULA (Fig. 10A). Teeth arranged in anteriorly V-shaped rows with half row consisting of about 70– 76 teeth at middle plate. Central, lateral, and marginal teeth monocuspid and spatulate-shaped with curved cusp. Distribution This species is currently known only from 2 localities: the type locality (Phu Pha Lom) and limestone hills in Loei Province (Fig. 1). Remarks The genitalia were originally described but without examination of the internal sculpture of penis. In this study, we examined 20 adult topotypic specimens to provide descriptions of the penial sheath, penial caecum, and flagellum that were not included in the original description. The penial sheath is very large and covers the entire penis (Fig. 5B). The short penial caecum, an extension of the penis, is located near the penis and epiphallus junction (Fig. 5B). This character is visible when penial sheath is removed. Its internal sculpture is rather smooth, unlike the penial sculpture, with its trapezoid-shaped pilasters (Fig. 5C). The Australian helicarionids, Nitor whitneyae Stanisic, 2010 has a penial caecum while other Nitor taxa do not have a penial caecum (Hyman & Köhler 2018). In Southeast Asian ariophantids, the presence or absence of a penial caecum is a discriminating character among species in genera such as Macrochlamys Gray, 1847 and Taphrenalla Pholyotha & Panha, 2020, and is supported by molecular studies (Pholyotha et al. 2018, 2021). The flagellum of A. clivicola is an extension of the epiphallus and is located near the insertion point of the vas deferens. It is somewhat small and short, and bound to the vas deferens by thin connective tissue. This feature is important for spermatophore formation before copulation (Tompa 1984; Baur 2010). However, during this study no spermatophores were observed in A. clivicola.

Sarika khmeriana Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act: 13BEB7E0-40BD-480C-ABA7-72798C9E6AF2 Table 1; Figs 4 A���B, 5, 6A���F Diagnosis Sarika khmeriana sp. nov. can be characterized by a large, depressed shell, rounded on the periphery. Shell colour dark brownish and usually with pale brownish (to whitish) umbilical area. Animal has dark grey body and left shell lobe is absent. Genitalia have rather long epiphallic caecum and inner wall of penis sculptured with triangular prism penial pilasters. Spermatophore head filament with irregularly serrated longitudinal folds; tail filament bearing two spines near sperm sac and branching spines along the entire tail filament length. Etymology The specific epithet ��� khmeriana ��� refers to the Khmer Empire, of which Cambodia is the residual state. Material examined Holotype CAMBODIA ��� 1 shell (width 24.2 mm, height 12.3 mm); Kampot Province, Dang Tong District, limestone outcrops near Totong Temple, locality code C041; 10��41���59.8��� N, 104��31���30.1��� E; CUMZ 7904. Paratypes CAMBODIA ��� 6 shells, 11 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7905 ��� 2 shells; same collection data as for preceding; NHMUK ��� 2 shells; same collection data as for preceding; ZRC. Other material CAMBODIA ��� 24 shells, 17 alcohol-preserved specimens; Kampot Province, Banteay Meas District, limestone outcrops at Prasat Phnom Totong Temple, locality code C042; 10��41���47.9��� N, 104��31���25.5��� E; CUMZ 7906. Description SHELL (Fig. 4 A���B). Depressed, large (shell width up to 24.2 mm, shell height up to 12.3 mm), rather thin, semi-translucent. Shell colour dark brownish on upper surface and at periphery; below periphery surrounding umbilicus pale to very pale brownish. Shell surface smooth, glossy; more glossy below periphery; suture rather shallow with narrow, whitish subsutural band. Spire slightly elevated; whorls 6���6��, increasing regularly; last whorl broadly rounded on periphery. Aperture obliquely crescentshaped; peristome simple. Columellar margin simple, slightly reflected near umbilicus. Umbilicus somewhat narrow and deep. EXTERNAL FEATURES (Fig. 5A). Living animals have monochrome dark grey body with pale grey foot sole. Caudal foss present; caudal horn elevated and large. Mantle edge well developed with three dorsal lobes and one shell lobe (see Pholyotha et al. 2018: fig. 1). Shape and size of dorsal lobes and right shell lobe (left shell lobe absent) similar to previous species. GENITALIA (Fig. 5 B���C). Atrium (at) enlarged, very short. Penis (p) cylindrical, with thin penial sheath covering proximal penis. Inner sculpture of penis very finely folded to nearly smooth then gradually transformed to triangular prism (rhombic base and acute angle on top) penial pilasters (pp) near epiphallus. Epiphallus (e) cylindrical, elongate, about two times penis length. Epiphallic caecum (ec) large, similar diameter as penis, straight and located near middle of epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallic caecum. Flagellum (fl) slender, somewhat long, about 1.5 times epiphallus length. Vas deferens (vd) a thin tube. Vagina (v) cylindrical, similar length as penis. Dart apparatus (da) cylindrical, rather large, long, attached to atrium at penis and vagina junction. Gametolytic sac (gs) enlarged, bulbous (spermatophore inside); gametolytic duct (gd) long, cylindrical. Free oviduct (fo) cylindrical, longer than vagina, proximal end encircled with thickened tissue. Oviduct large lobules; prostate gland running alongside oviduct. SPERMATOPHORE (Fig. 6 A���F). Sperm sac (ss) enlarged, elongate-oval. Head filament (hf) enlarged (most was missing) with irregularly serrated longitudinal folds. Tail filament (tf) very long tube, region close to sperm sac bearing two spines. Spine I simple, short; spine II with complicated branching into small, numerous spinules. Spines on tail filament starting just after spine II, with complicated branching into spinules, arranged alternate (Fig. 7D) or opposite (Fig. 7F). RADULA (Fig. 5D). Teeth arranged in wide-angle U-shape with half row formula: 1���(13���14)���55 teeth. Central tooth symmetrical tricuspid with triangular-shaped mesocone; ectocones very small. Lateral teeth asymmetrical tricuspid; mesocone large, pointed cusp; endocone small, located near the tip; ectocone larger than endocone, pointed cusp, located in middle of tooth. Marginal teeth occurring around tooth numbers 13���14, obliquely bicuspid; endocone elongate, pointed cusp; ectocone small, pointed cusp. Outermost teeth gradually reduced in size as cusps to small teeth. Distribution This new species is known from two locations very close to each other, on limestone outcrops. Totong Mountain (type locality) is a small karst with an old quarry, surrounded by housing areas and is adjacent to paddy fields (Fig. 1). The second locality, Prasat Phnom Totong, about 500 m south of the type locality, is a very large and active mining site of a cement factory. Remarks Sarika khmeriana sp. nov. is quite similar in terms of shell shape with S. lactoconcha sp. nov., but this species is distinct in possessing dark brown shell on upper surface and pale brownish (to whitish) surrounding umbilicus, and left shell lobe absent (four mantle lobes); whereas S. lactoconcha sp. nov. has a monochrome pale milky shell, and well-developed left shell lobe (five mantle lobes). This new species differs from S. resplendens in having a thin penial retractor muscle and the entire tail filament of spermatophore has branching spines, whereas the genitalia of S. resplendens (see Godwin-Austen 1907: fig. 3) have a large and thickened penial retractor muscle, and the tail filament of spermatophore is without a branching spine. Compared with other species of Sarika from Cambodia, S. khmeriana sp. nov. is rounded on the periphery while S. bocourti is obtusely angulated on the periphery, and this new species has a larger shell diameter than S. benoiti. Sarika khmeriana sp. nov. also differs from M. despecta (Mabille, 1887) from northern Vietnam in having an elevated spire and narrower umbilical opening., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Thach, Phanara, Chhuoy, Samol, Ngor, Peng Bun & Panha, Somsak, 2020, Land snail genus Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Cambodia, with description of three new species, pp. 1-21 in European Journal of Taxonomy 674 on pages 11-15, DOI: 10.5852/ejt.2020.674, http://zenodo.org/record/3908375, {"references":["Pholyotha A., Sutcharit C. & Panha S. 2018. The land snail genus Macrochlamys Gray, 1847 from Thailand, with descriptions of five new species (Pulmonata: Ariophantidae). Raffles Bulletin of Zoology 66: 763 - 781."]}

Sarika khmeriana Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act: 13BEB7E0-40BD-480C-ABA7-72798C9E6AF2 Table 1; Figs 4 A–B, 5, 6A–F Diagnosis Sarika khmeriana sp. nov. can be characterized by a large, depressed shell, rounded on the periphery. Shell colour dark brownish and usually with pale brownish (to whitish) umbilical area. Animal has dark grey body and left shell lobe is absent. Genitalia have rather long epiphallic caecum and inner wall of penis sculptured with triangular prism penial pilasters. Spermatophore head filament with irregularly serrated longitudinal folds; tail filament bearing two spines near sperm sac and branching spines along the entire tail filament length. Etymology The specific epithet ‘ khmeriana ’ refers to the Khmer Empire, of which Cambodia is the residual state. Material examined Holotype CAMBODIA • 1 shell (width 24.2 mm, height 12.3 mm); Kampot Province, Dang Tong District, limestone outcrops near Totong Temple, locality code C041; 10°41′59.8″ N, 104°31′30.1″ E; CUMZ 7904. Paratypes CAMBODIA • 6 shells, 11 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7905 • 2 shells; same collection data as for preceding; NHMUK • 2 shells; same collection data as for preceding; ZRC. Other material CAMBODIA • 24 shells, 17 alcohol-preserved specimens; Kampot Province, Banteay Meas District, limestone outcrops at Prasat Phnom Totong Temple, locality code C042; 10°41′47.9″ N, 104°31′25.5″ E; CUMZ 7906. Description SHELL (Fig. 4 A–B). Depressed, large (shell width up to 24.2 mm, shell height up to 12.3 mm), rather thin, semi-translucent. Shell colour dark brownish on upper surface and at periphery; below periphery surrounding umbilicus pale to very pale brownish. Shell surface smooth, glossy; more glossy below periphery; suture rather shallow with narrow, whitish subsutural band. Spire slightly elevated; whorls 6–6½, increasing regularly; last whorl broadly rounded on periphery. Aperture obliquely crescentshaped; peristome simple. Columellar margin simple, slightly reflected near umbilicus. Umbilicus somewhat narrow and deep. EXTERNAL FEATURES (Fig. 5A). Living animals have monochrome dark grey body with pale grey foot sole. Caudal foss present; caudal horn elevated and large. Mantle edge well developed with three dorsal lobes and one shell lobe (see Pholyotha et al. 2018: fig. 1). Shape and size of dorsal lobes and right shell lobe (left shell lobe absent) similar to previous species. GENITALIA (Fig. 5 B–C). Atrium (at) enlarged, very short. Penis (p) cylindrical, with thin penial sheath covering proximal penis. Inner sculpture of penis very finely folded to nearly smooth then gradually transformed to triangular prism (rhombic base and acute angle on top) penial pilasters (pp) near epiphallus. Epiphallus (e) cylindrical, elongate, about two times penis length. Epiphallic caecum (ec) large, similar diameter as penis, straight and located near middle of epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallic caecum. Flagellum (fl) slender, somewhat long, about 1.5 times epiphallus length. Vas deferens (vd) a thin tube. Vagina (v) cylindrical, similar length as penis. Dart apparatus (da) cylindrical, rather large, long, attached to atrium at penis and vagina junction. Gametolytic sac (gs) enlarged, bulbous (spermatophore inside); gametolytic duct (gd) long, cylindrical. Free oviduct (fo) cylindrical, longer than vagina, proximal end encircled with thickened tissue. Oviduct large lobules; prostate gland running alongside oviduct. SPERMATOPHORE (Fig. 6 A–F). Sperm sac (ss) enlarged, elongate-oval. Head filament (hf) enlarged (most was missing) with irregularly serrated longitudinal folds. Tail filament (tf) very long tube, region close to sperm sac bearing two spines. Spine I simple, short; spine II with complicated branching into small, numerous spinules. Spines on tail filament starting just after spine II, with complicated branching into spinules, arranged alternate (Fig. 7D) or opposite (Fig. 7F). RADULA (Fig. 5D). Teeth arranged in wide-angle U-shape with half row formula: 1–(13–14)–55 teeth. Central tooth symmetrical tricuspid with triangular-shaped mesocone; ectocones very small. Lateral teeth asymmetrical tricuspid; mesocone large, pointed cusp; endocone small, located near the tip; ectocone larger than endocone, pointed cusp, located in middle of tooth. Marginal teeth occurring around tooth numbers 13–14, obliquely bicuspid; endocone elongate, pointed cusp; ectocone small, pointed cusp. Outermost teeth gradually reduced in size as cusps to small teeth. Distribution This new species is known from two locations very close to each other, on limestone outcrops. Totong Mountain (type locality) is a small karst with an old quarry, surrounded by housing areas and is adjacent to paddy fields (Fig. 1). The second locality, Prasat Phnom Totong, about 500 m south of the type locality, is a very large and active mining site of a cement factory. Remarks Sarika khmeriana sp. nov. is quite similar in terms of shell shape with S. lactoconcha sp. nov., but this species is distinct in possessing dark brown shell on upper surface and pale brownish (to whitish) surrounding umbilicus, and left shell lobe absent (four mantle lobes); whereas S. lactoconcha sp. nov. has a monochrome pale milky shell, and well-developed left shell lobe (five mantle lobes). This new species differs from S. resplendens in having a thin penial retractor muscle and the entire tail filament of spermatophore has branching spines, whereas the genitalia of S. resplendens (see Godwin-Austen 1907: fig. 3) have a large and thickened penial retractor muscle, and the tail filament of spermatophore is without a branching spine. Compared with other species of Sarika from Cambodia, S. khmeriana sp. nov. is rounded on the periphery while S. bocourti is obtusely angulated on the periphery, and this new species has a larger shell diameter than S. benoiti. Sarika khmeriana sp. nov. also differs from M. despecta (Mabille, 1887) from northern Vietnam in having an elevated spire and narrower umbilical opening.

Sarika nana Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act: 48DF9AB1-369C-4930-A006-9E57AE9DBACB Table 1; Figs 4 C–D, 6G–J, 7 Diagnosis Sarika nana sp. nov. can be characterized by medium shell size, globosely depressed, pale yellowishbrown shell, and well-rounded periphery. Animal has dark grey body and five mantle lobes. Genitalia have a rather long epiphallic caecum, short penial caecum, rather large penial verge and oval-shaped penial pilasters. Spermatophore has smooth head filament and tail filament near sperm sac bearing two spines, and terminal one-third of tail filament contains a series of short branching spines. Etymology The specific epithet ‘ nana ’ is from the Latin word ‘ nanus ’ meaning “dwarf” and refers to the small-sized species in this genus. Material examined Holotype CAMBODIA • 1 shell (width 12.6 mm, height 6.8 mm); Takeo Province, Kiri Vong District, the conglomerate hills at Phnom Bayang Temple, locality code C036; 10°38′28.2″ N, 104°50′35.8″ E; CUMZ 7907. Paratypes CAMBODIA • 24 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7908 • 2 shells; same collection data as for preceding; NHMUK • 2 shells; same collection data as for preceding; ZRC. Description SHELL (Fig. 4 C–D). Globosely depressed, medium-sized (shell width up to 12.3 mm, shell height up to 6.8 mm), thin, rather translucent. Shell surface smooth, shiny; more shiny below periphery; shell colour pale yellowish brown. Entire shell consisting of 5½–6 whorls increasing regularly, separated by shallow suture. Spire slightly elevated; last whorl broad, well-rounded. Aperture obliquely oval-lunate shaped. Peristome simple. Columellar margin simple, slightly expanded near umbilicus. Umbilicus opened, wide, deep. EXTERNAL FEATURES (Fig. 7A). Living animals having monochrome pale grey body, foot sole. Caudal foss, large caudal horn present. Mantle edge well developed, dark colour, with three dorsal lobes and two shell lobes (see Pholyotha et al. 2018: fig. 1). Dorsal lobes and shell lobes similar to those of S. lactoconcha sp. nov. GENITALIA (Fig. 7 B–C). Atrium (at) very short. Penis (p) short, cylindrical with thin penial sheath covering proximal penis. Distal penis slightly enlarged with penial caecum (pc), corresponding to penial verge. Inner sculpture of penis proximally with smooth surface then transformed to thickened, corrugated transverse-folded penial pilasters (pp) surrounding penial verge near distal end. Penial verge (pv) large with blunt tip. Epiphallus (e) cylindrical, about twice penis length. Epiphallic caecum (ec) similar diameter as epiphallus, straight, located near proximal epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallus. Flagellum (fl) slender, short, about half the length of epiphallus. Vas deferens (vd) thin tube. Vagina (v) cylindrical, little longer than penis. Dart apparatus (da) cylindrical, rather large and long, connected to atrium at vagina and penis junction. Gametolytic sac (gs) enlarged, bulbous (spermatophore inside); gametolytic duct (gd) cylindrical, long. Free oviduct (fo) cylindrical, same length as vagina, proximal end encircled with thickened, brownish tissue. Oviduct enlarged lobules; prostate gland running alongside oviduct. SPERMATOPHORE (Fig. 6 G–J). Sperm sac (ss) enlarged, elongate-oval. Head filament (hf) located subapical of sperm sac, with long, smooth surface. Tail filament (tf) about two times longer than sperm sac, region close to sperm sac bearing two spines. Spine I simple, curved, with dull tip. Spine II large, branching into spinules (antler like). Region furthest away smooth, without spine; terminal part (about one-fourth of its length) consisting of short to long branching spines arranged in row or encircling tip. RADULA (Fig. 7D). Teeth arranged in wide-angle U-shape with half row formula: 1–(10–11)–46 teeth. Central tooth symmetrical tricuspid; mesocone large, lanceolate shape; ectocones small with triangular shape. Lateral teeth asymmetrical tricuspid with large, pointed cusp mesocone; endocone small, pointed cusp, located near tip; ectocone rather large, triangular-shaped, located in middle of tooth. Marginal teeth starting around tooth numbers 10–11, obliquely bicuspid; endocone elongate, pointed cusp; ectocone small, pointed cusp. Outermost teeth gradually smaller in size from lateral teeth to edge. Distribution This new species is known only from the conglomerate mountain Phnom Bayang (type locality; Fig. 1). The habitat at the collection site is an evergreen forest mixed with fruit orchards and with outcroppings of large granite boulders. This location is surrounded by villages and is adjacent to paddy fields. Remarks Sarika nana sp. nov., a medium-sized species, can be distinguished from all species of Sarika recorded from mainland Indochina by having a penial verge. Compared to medium-sized species of Macrochlamys, body whorl of S. nana sp. nov. is relatively broader and more well-rounded on the periphery, umbilicus is relatively wider and aperture opening is less convex than M. excepta (Mabille, 1887) (Fig. 4E) and M. zero (Mabille, 1887) (Fig. 4F). The type locality of the new species is about 1000 km from the two species described from Northern Vietnam. The Thai species M. brunnea Möllendorff, 1902 has much narrower umbilical opening than this new species (see Pholyotha et al. 2018: fig. 8a). Unfortunately, the anatomical data of M. brunnea, M. excepta and M. zero is unavailable for further comparison.

Genus Sarika Godwin-Austen, 1907 Sarika Godwin-Austen, 1907: 179. ��� Blanford & Godwin-Austen 1908: 276. ��� Zilch 1959: 325. ��� Schileyko 2002: 1288. ��� Pholyotha et al. 2020. Type species Helix resplendens Philippi, 1846, by original designation., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Thach, Phanara, Chhuoy, Samol, Ngor, Peng Bun & Panha, Somsak, 2020, Land snail genus Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Cambodia, with description of three new species, pp. 1-21 in European Journal of Taxonomy 674 on page 5, DOI: 10.5852/ejt.2020.674, http://zenodo.org/record/3908375, {"references":["Blanford W. T. & Godwin-Austen H. H. 1908. Mollusca: Testacellidae and Zonitidae. In: Bingham CT (ed.) The Fauna of British India including Ceylon and Burma. Taylor and Francis, London.","Zilch A. 1959. Gastropoda, Euthyneura. In: Schindewolf O. H. (ed.) Handbuch der Palaozoologie, Volume 6: 1 - 400. Gebruder Borntraeger, Berlin.","Pholyotha A., Sutcharit C., Tongkerd P., Lin A. & Panha S. 2020. Taxonomic revision of the land snail genera Macrochlamys Gray, 1847 and Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Southeastern Myanmar, with descriptions of three new species. Molluscan Research 40: 183 - 204. https: // doi. org / 10.1080 / 13235818.2020.1723041","Philippi R. A. 1846. Vier neue Konchylienarten. Zeitschrift fur Malakozoologie 3: 191 - 192."]}

Sarika nana Pholyotha & Panha sp. nov. urn:lsid:zoobank.org:act: 48DF9AB1-369C-4930-A006-9E57AE9DBACB Table 1; Figs 4 C���D, 6G���J, 7 Diagnosis Sarika nana sp. nov. can be characterized by medium shell size, globosely depressed, pale yellowishbrown shell, and well-rounded periphery. Animal has dark grey body and five mantle lobes. Genitalia have a rather long epiphallic caecum, short penial caecum, rather large penial verge and oval-shaped penial pilasters. Spermatophore has smooth head filament and tail filament near sperm sac bearing two spines, and terminal one-third of tail filament contains a series of short branching spines. Etymology The specific epithet ��� nana ��� is from the Latin word ��� nanus ��� meaning ���dwarf��� and refers to the small-sized species in this genus. Material examined Holotype CAMBODIA ��� 1 shell (width 12.6 mm, height 6.8 mm); Takeo Province, Kiri Vong District, the conglomerate hills at Phnom Bayang Temple, locality code C036; 10��38���28.2��� N, 104��50���35.8��� E; CUMZ 7907. Paratypes CAMBODIA ��� 24 alcohol-preserved specimens; same collection data as for holotype; CUMZ 7908 ��� 2 shells; same collection data as for preceding; NHMUK ��� 2 shells; same collection data as for preceding; ZRC. Description SHELL (Fig. 4 C���D). Globosely depressed, medium-sized (shell width up to 12.3 mm, shell height up to 6.8 mm), thin, rather translucent. Shell surface smooth, shiny; more shiny below periphery; shell colour pale yellowish brown. Entire shell consisting of 5�����6 whorls increasing regularly, separated by shallow suture. Spire slightly elevated; last whorl broad, well-rounded. Aperture obliquely oval-lunate shaped. Peristome simple. Columellar margin simple, slightly expanded near umbilicus. Umbilicus opened, wide, deep. EXTERNAL FEATURES (Fig. 7A). Living animals having monochrome pale grey body, foot sole. Caudal foss, large caudal horn present. Mantle edge well developed, dark colour, with three dorsal lobes and two shell lobes (see Pholyotha et al. 2018: fig. 1). Dorsal lobes and shell lobes similar to those of S. lactoconcha sp. nov. GENITALIA (Fig. 7 B���C). Atrium (at) very short. Penis (p) short, cylindrical with thin penial sheath covering proximal penis. Distal penis slightly enlarged with penial caecum (pc), corresponding to penial verge. Inner sculpture of penis proximally with smooth surface then transformed to thickened, corrugated transverse-folded penial pilasters (pp) surrounding penial verge near distal end. Penial verge (pv) large with blunt tip. Epiphallus (e) cylindrical, about twice penis length. Epiphallic caecum (ec) similar diameter as epiphallus, straight, located near proximal epiphallus. Penial retractor muscle (prm) thin, attached at tip of epiphallus. Flagellum (fl) slender, short, about half the length of epiphallus. Vas deferens (vd) thin tube. Vagina (v) cylindrical, little longer than penis. Dart apparatus (da) cylindrical, rather large and long, connected to atrium at vagina and penis junction. Gametolytic sac (gs) enlarged, bulbous (spermatophore inside); gametolytic duct (gd) cylindrical, long. Free oviduct (fo) cylindrical, same length as vagina, proximal end encircled with thickened, brownish tissue. Oviduct enlarged lobules; prostate gland running alongside oviduct. SPERMATOPHORE (Fig. 6 G���J). Sperm sac (ss) enlarged, elongate-oval. Head filament (hf) located subapical of sperm sac, with long, smooth surface. Tail filament (tf) about two times longer than sperm sac, region close to sperm sac bearing two spines. Spine I simple, curved, with dull tip. Spine II large, branching into spinules (antler like). Region furthest away smooth, without spine; terminal part (about one-fourth of its length) consisting of short to long branching spines arranged in row or encircling tip. RADULA (Fig. 7D). Teeth arranged in wide-angle U-shape with half row formula: 1���(10���11)���46 teeth. Central tooth symmetrical tricuspid; mesocone large, lanceolate shape; ectocones small with triangular shape. Lateral teeth asymmetrical tricuspid with large, pointed cusp mesocone; endocone small, pointed cusp, located near tip; ectocone rather large, triangular-shaped, located in middle of tooth. Marginal teeth starting around tooth numbers 10���11, obliquely bicuspid; endocone elongate, pointed cusp; ectocone small, pointed cusp. Outermost teeth gradually smaller in size from lateral teeth to edge. Distribution This new species is known only from the conglomerate mountain Phnom Bayang (type locality; Fig. 1). The habitat at the collection site is an evergreen forest mixed with fruit orchards and with outcroppings of large granite boulders. This location is surrounded by villages and is adjacent to paddy fields. Remarks Sarika nana sp. nov., a medium-sized species, can be distinguished from all species of Sarika recorded from mainland Indochina by having a penial verge. Compared to medium-sized species of Macrochlamys, body whorl of S. nana sp. nov. is relatively broader and more well-rounded on the periphery, umbilicus is relatively wider and aperture opening is less convex than M. excepta (Mabille, 1887) (Fig. 4E) and M. zero (Mabille, 1887) (Fig. 4F). The type locality of the new species is about 1000 km from the two species described from Northern Vietnam. The Thai species M. brunnea M��llendorff, 1902 has much narrower umbilical opening than this new species (see Pholyotha et al. 2018: fig. 8a). Unfortunately, the anatomical data of M. brunnea, M. excepta and M. zero is unavailable for further comparison., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak, Thach, Phanara, Chhuoy, Samol, Ngor, Peng Bun & Panha, Somsak, 2020, Land snail genus Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from Cambodia, with description of three new species, pp. 1-21 in European Journal of Taxonomy 674 on pages 15-18, DOI: 10.5852/ejt.2020.674, http://zenodo.org/record/3908375, {"references":["Pholyotha A., Sutcharit C. & Panha S. 2018. The land snail genus Macrochlamys Gray, 1847 from Thailand, with descriptions of five new species (Pulmonata: Ariophantidae). Raffles Bulletin of Zoology 66: 763 - 781."]}

Macrochlamys coleus Pholyotha & Panha, new species (Figs. 2B, 3C, D, 4F–I, 6D–F) Material examined. Holotype (Fig. 3C; shell height 6.6 mm, shell width 13.0 mm, aperture height 5.0 mm, aperture width 6.2 mm, 5½ whorls) (CUMZ 7104), limestone outcrops at Wat Sunantha Wanaram (Temple), Sai Yok District, Kanchanaburi Province, Thailand, 14° 32′01.6″N, 98° 50′13.8″E. Paratypes: one shell (Fig. 3D; shell height 6.0 mm, shell width 12.3 mm, aperture height 4.5 mm, aperture width 6.1 mm, 5¼ whorls) (CUMZ 7105), 10 specimens (CUMZ 7106), same data as holotype. Etymology. The specific epithet “ coleus ”, from the Latin word meaning “sheath”, refers to the well-developed tissue covering between the vagina and dart apparatus. Description. Shell medium-sized (Fig. 3C, D; shell height up to 6.6 mm; shell width up to 13.0 mm), dextral, depressed, slightly thick, translucent brown in colour. Shell surface nearly smooth, with very fine growth lines. Embryonic shell surface smooth, with about 2½ whorls. Whorls 5–6, increasing regularly. Suture wide and shallow, channel-shaped. Spire depressed, apex slightly raised with spire angle of about 148–152°. Last whorl well rounded. Aperture crescent ovoid shaped, obliquely open, with simple lip. Columellar margin little developed and slightly reflected near umbilicus. Umbilicus narrowly open. Genital organs. Atrium (at) short. Penis prolonged, cylindrical-shaped with rounded bulge corresponding to penial verge. Penial caecum (pc) slightly prolonged. Epiphallus (e) slender tube about two times longer than penis. Epiphallic caecum (ec) coiled about one circle, located at middle of epiphallus and attached with thick penial retractor muscle (prm). Flagellum (fl) short, cylindrical shaped and stretched around half of epiphallus length. Vas deference (vd) a thin tube connected between distal end of epiphallus and free oviduct (Fig. 4F). Inner penial wall supported proximally with small and irregular wrinkled penial pilasters (pp), distally with thin longitudinal and wrinkled folds. Penial verge (pv) very small and short, situated at distal end of penis (Fig. 4G). Vagina (v) slightly long, almost same length as penis and cylindrical. Dart apparatus (da) long, enlarged cylindrical shape, located at proximal end of vagina, with thick connective tissue encircled at proximal end (asterisk in Fig. 4F). Gametolytic sac (gs) elongate and bulbous. Gametolytic duct (gd) long and cylindrical (one spermatophore in Fig. 4F). Free oviduct (fo) short, about similar length to flagellum, proximal end encircled with brownish tissue. Oviduct (ov) large lobules with prostate gland (pg) running alongside (Fig. 4F). Spermatophore long, needle-shaped and translucent (Fig. 4H). Head filament (hf) short, gradually tapering to a point (Fig. 4I). Sperm sac (ss) enlarged, cylindrical capsule-shaped with sperm mass. Tail filament (tf) long, curved with many spines. Region close to sperm sac bear a single trichotomous spine divided into three pointed tips. Middle region with a row of five, long curved spines. Region furthest away from sperm sac contains small cluster of short spines (Fig. 4H). Radula. Each row contains about 92 teeth with formula (45- (12-11)-1-(11-12)-46). Central tooth symmetric tricuspid. Lateral teeth asymmetric tricuspid. Marginal teeth obliquely bicuspid starting from tooth number 11–12 (Fig. 6D–F). External features. Animal with reticulated skin. Head, eye stalks and body dark grey, and tail orange (Fig. 2B). Caudal foss (cf) long and narrow. Caudal horn (ch) large and dark grey in colour. Mantle edge (shell lobes and dorsal lobes) well developed, orange with black pigmented spots spread all over. Shell lobes and dorsal lobes similar in morphology to M. aurantia new species. Snails secrete light orange slime when disturbed. Distribution and habitat. This new species is currently known only from the type locality, an area of limestone outcrops with a relatively low population density. The snails were mostly found on decaying leaf litter or sometimes climbing on limestone walls. Remarks. Macrochlamys coleus new species is distinguished by a depressed shell, dark brown in colour, and rather shallowly channelled suture. The genitalia have one circle of coiled epiphallic caecum, and dart apparatus with a thick connective tissue encircling the proximal end. Its spermatophore has a single trichotomously branched spine at the proximal end, five long spines in the middle, and a cluster of small spines at the distal end of tail filaments. Its radula morphology is very similar to M. aurantia. This new species is close to M. aurantia new species, but can be differentiated by its small last whorl and shallow channelshaped suture. Anatomically, the genitalia have a short flagellum and well-developed connective tissue surrounding the proximal end of the dart apparatus; characters missing in M. aurantia new species. In addition, the spermatophore of this new species has a trichotomous spine on the tail filament close to the sperm sac and a row of long and curved spines on the middle part of the tail filament, while M. aurantia new species has one dichotomous spine and two simple spines on the tail filament close to the sperm sac. This new species differs from M. hypoleuca (Blanford, 1865) and M. nebulosa (Blanford, 1865) from Myanmar by its depressed shell with a broad last whorl and dark brown shell colour. In comparison, M. hypoleuca has a two-toned shell that is brown above the periphery and white below, while M. nebulosa has a conoidal, depressed, shell that is bluntly angulated at the periphery., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak & Panha, Somsak, 2018, The land snail genus Macrochlamys Gray, 1847 from Thailand, with descriptions of five new species (Pulmonata: Ariophantidae), pp. 763-781 in Raffles Bulletin of Zoology 66 on page 769, DOI: 10.5281/zenodo.5460634, {"references":["Blanford WT (1865) Contributions to Indian Malacology, No. V. Descriptions of new land shells from Arakan, Pegu, and Ava; with notes on the distribution of described species. Journal of the Asiatic Society of Bengal, 34: 66 - 68."]}

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Macrochlamys kelantanensis Möllendorff, 1902 (Figs. 2F, 8B–D, 9C, D, 10G–I) Macrochlamys hardwickei kelantanensis Möllendorff, 1902a: 137 (type locality: Kelantan, Ostküste der Halbinsel Malacca [Kelantan, east coast of Peninsula Malaysia]) – Maassen, 2001: 110. Material examined. Holotype (SMF 227098), one paratype shell (SMF 227099), Kelantan, east coast of Peninsula Malaysia. Non type material: THAILAND. five shells (CUMZ 7120), 16 specimens (CUMZ 7121), Mae Chan District, Chiang Rai Province, 20° 08′38.7″N 99° 51′21.4″E; 32 specimens (CUMZ 7122), Nong Han, San Sai District, Chiang Mai Province, 18° 53′23.7″N 98° 59′54.7″E; two specimens (CUMZ 7123) Mae Sot District, Tak Province, 16° 43′26.9″N 98° 35′06.0″E; one shell (CUMZ 7124), 10 specimens (CUMZ 7125), Lam Kaen, Phang-Nga Province, 8° 35′48.5″N 98° 15′22.4″E; six specimens (CUMZ 7126), Koh Chang District, Trat Province, 12° 04′36.8″N 102° 22′02.6″E. MALAYSIA: 15 specimens (CUMZ 7127), Bukit Bunga, Kampung Jakar, Ayer Lanas, Kelantan, 5° 49′8.8″N 101° 54′40.4″E; one specimen (CUMZ 7128), Gunung Reng Batu Melintang, Jeli, Kelantan, 5° 42′54.1″N 101° 44′43.3″E; one shell (CUMZ 7132), 46 specimens (CUMZ 7129), Jalan Bunga, Merbok, Kedah, 5° 43′27.7″N 100° 23′22.3″E; one shell (Fig. 8C) (CUMZ 7130), 13 specimens (CUMZ 7131), Kampung Seberang Pekan, Baling, Kedah, 5° 41′13.4″N 100° 54′54.2″E. Description. Shell medium to large (Fig. 8B–D; shell height up to 13.0 mm; shell width up to 24.0 mm), dextral, spire depressed to low-conical, thin, translucent, and pale brown in colour. Shell surface nearly smooth with very thin growth lines. Embryonic shell surface smooth, with about 2½ whorls. Whorls 5–6, regularly increasing. Suture impressed. Spire depressed conic to low conical. Apex raised with a spire angle of about 134–142°. Last whorl large with wellrounded periphery. Aperture crescent shape, open obliquely with simple lip. Columellar margin slightly reflected near umbilicus. Umbilicus narrowly open and deep. Genital organs. Atrium (at) very short. Penis (p) short and cylindrical-shaped. Epiphallus (e) short, slightly smaller than penis diameter, about four times longer than penis. Epiphallic caecum (ec) somewhat enlarged, thick, almost same diameter as penis and coiled about two circles. Penial retractor muscle thin and long. Flagellum (fl) long, cylindrical-shaped, about same length as epiphallus. Vas deference (vd) a long tube between distal end of epiphallus and free oviduct (Fig. 9C). Inner wall of penis supported with very small and irregular penial pilasters (pp). Penial verge (pv) small, cylindrical and located at distal end of penis (Fig. 9D). Vagina (v) short about same length as penis and cylindricalshaped. Dart apparatus (da) very large, long and cylindrical, located at proximal end of vagina. Gametolytic sac (gs) bulbous; gametolytic duct (gd) long, cylindrical and slightly swollen near vagina. Free oviduct (fo) very short, triangular shape and entirely encircled with thick tissues. Oviduct (ov) large lobules; prostate gland (pg) runs alongside oviduct (Fig. 9C). Radula. Radula morphology very similar to M. aurantia new species. Each row contains about 111 teeth with formula (55- (17-16)-1-(15-16)-55). Central tooth symmetrical tricuspid; mesocone large with dull cusp. Lateral teeth asymmetrical tricuspid with very small endocone. Marginal teeth with elongate bicuspid start around tooth number 15 to 17 (Fig. 10G–I). External features. Animal with reticulated skin. Foot and body pale yellowish-grey, slightly darker on dorsal side. Head and tentacles darker grey. Caudal foss (cf) long and narrow, caudal horn (ch) raised, pale brownish colour. Mantle edge (shell lobes and dorsal lobes) well developed, dull brownish in colour (Fig. 2F). The snails secrete yellowish slime when disturbed. Remarks. This species was originally nominated as a subspecies of M. hardwickei Godwin-Austen, 1883 from Lower Bengal, Sylhet and Western Assam (Möllendorff, 1902a). It is here raised to full species level. It differs from M. hardwickei sensu stricto by its larger shell, the cylindrically shaped penis, and enlarged and short cylindrical appearance of the free oviduct versus a smaller shell, enlarged and triangular-shaped penis, and extremely long free oviduct of M. hardwickei (see Godwin-Austen, 1883: 105–107, pl. 23, figs, 1–4; pl. 28, fig. 1). Macrochlamys malaccana from Peninsular Malaysia has a relatively smaller shell that bears a distinct dark brown spiral line at the suture (see Foon et al., 2017). Unfortunately, genitalia data of M. malaccana is not available for comparison. Macrochlamys kelantanensis is usually ground dwelling and is often associated with anthropogenic habitats, such as plantations, fruit orchards, gardens or parks. This could explain their wide dispersal and it is believed to have been accidentally introduced through horticultural and agricultural trade activities., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak & Panha, Somsak, 2018, The land snail genus Macrochlamys Gray, 1847 from Thailand, with descriptions of five new species (Pulmonata: Ariophantidae), pp. 763-781 in Raffles Bulletin of Zoology 66 on pages 775-778, DOI: 10.5281/zenodo.5460634, {"references":["Mollendorff O von (1902 a) Binnenmollusken aus Hinterindien. 1. Land schnecken von Kelantan, Ostkuste der Halbinsel Malacca. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 34: 135 - 149.","Maassen WJM (2001) A preliminary checklist of the non-marine molluscs of West-Malaysia. \" A Handlist \". De Kreukel, Amsterdam, 155 pp.","Godwin-Austen HH (1883 - 1907) Land and Freshwater Mollusca of India, Including South Arabia, Baluchistan, Afghanistan, Kashmir, Nepal, Burmah, Pegu, Tenasserim, Malay Peninsula, Ceylon, and other Islands of the Indian Ocean. Taylor and Francis, London, Volume 1 (1883 - 1887): 67 - 206, pls. 13 - 62; Volume 2 (1898 - 1907): 47 - 238, pls. 70 - 117.","Foon JK, Clements GR & Liew T-S (2017) Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia. ZooKeys, 682: 1 - 94."]}

Macrochlamys aurantia Pholyotha & Panha, new species (Figs. 2A, 3A, B, 4A–E, 6A–C) Material examined. Holotype (Fig. 3A; shell height 8.0 mm, shell width 14.0 mm, aperture height 6.0 mm, aperture width 7.2 mm, 5⅝ whorls) (CUMZ 7101), limestone outcrop at Wat Uthum Phon Wanaram (Temple), Huai Kayeng Village, Thong Pha Phum District, Kanchanaburi Province, Thailand, 14°41′52.6″N, 98°31′32.3″E. Paratypes: three shells (Fig. 3B; shell height 8.0 mm, shell width 13.9 mm, aperture height 6.5 mm, aperture width 7.1 mm, 5⅞ whorls) (CUMZ 7102), 12 specimens (CUMZ 7103), one shell (NHMUK), one shell (ZRC.MOL.13771), same data as holotype. Etymology. The specific name “ aurantia ” is from Latin “ aurantium ” meaning “orange”, and refers to the prominent orange or reddish orange posterior part of its body. Description. Shell medium-sized (Fig. 3A, B; shell height up to 8.2 mm; shell width up to 14.0 mm), dextral, comparatively depressed, thin but not fragile, semi-translucent, shiny and yellowish brown in colour. Shell surface smooth with fine growth lines. Embryonic shell small, about 2½ whorls with smooth surface. Whorls 5–6, regularly increasing. Suture wide and deeply channelled. Spire depressed, apex little raised, spire angle about 152–156°. Last whorl large, periphery rounded. Aperture oval-lunate, open obliquely, lip simple. Columellar edge slightly thickened and a little reflected over the narrowly open umbilicus. Genital organs. Atrium (at) short. Penis prolonged, slightly enlarged and cylindrical-shaped. Distally cylindrical and corresponding to penial verge. Penial caecum (pc) slightly prolonged. Epiphallus (e) slender tube, about two times length of penis. Epiphallic caecum (ec) coiled about one circle, located at middle of epiphallus and attached with thick penial retractor muscle (prm). Flagellum (fl) large, irregular coiled and length around half of epiphallus length. Vas deference (vd) slim tube connected between distal end of epiphallus and free oviduct (Fig. 4A). Internal wall of penis with very small and oblique wrinkled penial pilasters (pp). Penial verge (pv) small, thick and located at distal end of penis (Fig. 4B). Vagina (v) long, cylindrical-shape, about same length as penis. Dart apparatus (da) small, cylindrical-shape and situated at proximal end of vagina. Gametolytic sac (gs) prolonged and bulbous. Gametolytic duct (gd) long and cylindrical (two spermatophores in Fig. 4A). Free oviduct (fo) a long slender tube, proximal end encircled with thick brownish tissue. Oviduct (ov) large lobules, with prostate gland (pg) running alongside oviduct (Fig. 4A). Spermatophore long, needle-shape and translucent (Fig. 4C–E). Head filament (hf) short, gradually thinning to terminal point (Fig. 4D). Sperm sac (ss) a cylindrical capsule, containing sperm mass. Tail filament (tf) very long and cylindrical. Region close to sperm sac bearing three spines. First one dichotomous and split into two short spines, second one curved, located on same base as previous, third one simple, long and curved (Fig. 4D). Region furthest from sperm sac with small spine cluster near tip (Fig. 4E). Out of 10 specimens examined, seven contain one spermatophore and three contain two spermatophores in gametolytic organs. Radula. Teeth arranged in a U-shape, with about 103 teeth in each row with formula (48-(12-10)-1-(10-11)-54). Central tooth symmetrical, tricuspid with large and lanceolate mesocone, ectocones small and pointed cusps. Lateral teeth asymmetrical tricuspid. Endocone small, located near tip, mesocone large, triangular with pointed cusp. Ectocone larger than edocone and located near tooth base. Marginal teeth start around tooth number 10–12, obliquely bicuspid, elongate and narrower than others. Endocone large, ectocone smaller with pointed cusp (Fig. 6A–C). External features. Animal with reticulated skin. Head to eye stalks dark grey, body and tail deep yellow-orange. Caudal foss (cf) long and narrow. Caudal horn (ch) raised, large and greyish-orange. Mantle edge (shell lobes and dorsal lobes) well developed, dark to bright orange in colour. Shell lobes large and long. Right shell lobe (rsl) larger and longer than left shell lobe (lsl). Dorsal lobes large and broad. Right dorsal lobe (rdl) larger than both anterior left dorsal lobe (ant-ldl) and posterior left dorsal lobe (post-ldl). Snails secrete light orange slime when disturbed (Fig. 2A). Distribution and habitat. Macrochlamys aurantia new species was usually found on the surface of limestone walls and in rock crevices. Some individuals were encountered creeping on the leaves of a bush or tree trunk close to the limestone outcrop during our surveys. This species is probably locally endemic, and is currently known only from the type locality, where the population density is rather abundant. Remarks. Macrochlamys aurantia new species can be distinguished by the depressed spire, yellowish colour, large and rounded last whorl, and a wide and deep-channelled suture. The genitalia have long penis and vagina, one circle of coiled epiphallic caecum and a small dart apparatus located at the base of the vagina opposite the penis. Spermatophore has three spines at the proximal end and a cluster of small spines at the distal end of the tail filament. This new species can be distinguished from M. consepta (Benson, 1860) and M. chaos Blanford, 1905 from Myanmar by its depressed shell with a wide deeply impressed suture, and broad last whorl and aperture. In contrast, M. consepta has an almost flat shell with shallow suture, and the last whorl and aperture are not much broader. Macrochlamys chaos has a conoidly depressed shell with shallow suture, and narrow last whorl and aperture. In addition, this new species can be distinguished from all other known species by its spermatophore with three spines at the proximal end, and the cluster of small spines at the distal end of the tail filament., Published as part of Pholyotha, Arthit, Sutcharit, Chirasak & Panha, Somsak, 2018, The land snail genus Macrochlamys Gray, 1847 from Thailand, with descriptions of five new species (Pulmonata: Ariophantidae), pp. 763-781 in Raffles Bulletin of Zoology 66 on page 767, DOI: 10.5281/zenodo.5460634, {"references":["Benson WH (1860) Characters of new land-shells from Burmah and the Andamans. Annals and Magazine of Natural History, Series 3, Volume 6: 190 - 195.","Blanford WT (1905) Descriptions of Indian and Burmese land-shells referred to the genera Macrochlamys, Bensonia, Taphrospira, (gen. nov.), Microcystina, Euplecta, and Polita. Proceedings of the Zoological Society of London, 2: 441 - 447."]}

Macrochlamys coleus Pholyotha & Panha, new species (Figs. 2B, 3C, D, 4F–I, 6D–F) Material examined. Holotype (Fig. 3C; shell height 6.6 mm, shell width 13.0 mm, aperture height 5.0 mm, aperture width 6.2 mm, 5½ whorls) (CUMZ 7104), limestone outcrops at Wat Sunantha Wanaram (Temple), Sai Yok District, Kanchanaburi Province, Thailand, 14° 32′01.6″N, 98° 50′13.8″E. Paratypes: one shell (Fig. 3D; shell height 6.0 mm, shell width 12.3 mm, aperture height 4.5 mm, aperture width 6.1 mm, 5¼ whorls) (CUMZ 7105), 10 specimens (CUMZ 7106), same data as holotype. Etymology. The specific epithet “ coleus ”, from the Latin word meaning “sheath”, refers to the well-developed tissue covering between the vagina and dart apparatus. Description. Shell medium-sized (Fig. 3C, D; shell height up to 6.6 mm; shell width up to 13.0 mm), dextral, depressed, slightly thick, translucent brown in colour. Shell surface nearly smooth, with very fine growth lines. Embryonic shell surface smooth, with about 2½ whorls. Whorls 5–6, increasing regularly. Suture wide and shallow, channel-shaped. Spire depressed, apex slightly raised with spire angle of about 148–152°. Last whorl well rounded. Aperture crescent ovoid shaped, obliquely open, with simple lip. Columellar margin little developed and slightly reflected near umbilicus. Umbilicus narrowly open. Genital organs. Atrium (at) short. Penis prolonged, cylindrical-shaped with rounded bulge corresponding to penial verge. Penial caecum (pc) slightly prolonged. Epiphallus (e) slender tube about two times longer than penis. Epiphallic caecum (ec) coiled about one circle, located at middle of epiphallus and attached with thick penial retractor muscle (prm). Flagellum (fl) short, cylindrical shaped and stretched around half of epiphallus length. Vas deference (vd) a thin tube connected between distal end of epiphallus and free oviduct (Fig. 4F). Inner penial wall supported proximally with small and irregular wrinkled penial pilasters (pp), distally with thin longitudinal and wrinkled folds. Penial verge (pv) very small and short, situated at distal end of penis (Fig. 4G). Vagina (v) slightly long, almost same length as penis and cylindrical. Dart apparatus (da) long, enlarged cylindrical shape, located at proximal end of vagina, with thick connective tissue encircled at proximal end (asterisk in Fig. 4F). Gametolytic sac (gs) elongate and bulbous. Gametolytic duct (gd) long and cylindrical (one spermatophore in Fig. 4F). Free oviduct (fo) short, about similar length to flagellum, proximal end encircled with brownish tissue. Oviduct (ov) large lobules with prostate gland (pg) running alongside (Fig. 4F). Spermatophore long, needle-shaped and translucent (Fig. 4H). Head filament (hf) short, gradually tapering to a point (Fig. 4I). Sperm sac (ss) enlarged, cylindrical capsule-shaped with sperm mass. Tail filament (tf) long, curved with many spines. Region close to sperm sac bear a single trichotomous spine divided into three pointed tips. Middle region with a row of five, long curved spines. Region furthest away from sperm sac contains small cluster of short spines (Fig. 4H). Radula. Each row contains about 92 teeth with formula (45- (12-11)-1-(11-12)-46). Central tooth symmetric tricuspid. Lateral teeth asymmetric tricuspid. Marginal teeth obliquely bicuspid starting from tooth number 11–12 (Fig. 6D–F). External features. Animal with reticulated skin. Head, eye stalks and body dark grey, and tail orange (Fig. 2B). Caudal foss (cf) long and narrow. Caudal horn (ch) large and dark grey in colour. Mantle edge (shell lobes and dorsal lobes) well developed, orange with black pigmented spots spread all over. Shell lobes and dorsal lobes similar in morphology to M. aurantia new species. Snails secrete light orange slime when disturbed. Distribution and habitat. This new species is currently known only from the type locality, an area of limestone outcrops with a relatively low population density. The snails were mostly found on decaying leaf litter or sometimes climbing on limestone walls. Remarks. Macrochlamys coleus new species is distinguished by a depressed shell, dark brown in colour, and rather shallowly channelled suture. The genitalia have one circle of coiled epiphallic caecum, and dart apparatus with a thick connective tissue encircling the proximal end. Its spermatophore has a single trichotomously branched spine at the proximal end, five long spines in the middle, and a cluster of small spines at the distal end of tail filaments. Its radula morphology is very similar to M. aurantia. This new species is close to M. aurantia new species, but can be differentiated by its small last whorl and shallow channelshaped suture. Anatomically, the genitalia have a short flagellum and well-developed connective tissue surrounding the proximal end of the dart apparatus; characters missing in M. aurantia new species. In addition, the spermatophore of this new species has a trichotomous spine on the tail filament close to the sperm sac and a row of long and curved spines on the middle part of the tail filament, while M. aurantia new species has one dichotomous spine and two simple spines on the tail filament close to the sperm sac. This new species differs from M. hypoleuca (Blanford, 1865) and M. nebulosa (Blanford, 1865) from Myanmar by its depressed shell with a broad last whorl and dark brown shell colour. In comparison, M. hypoleuca has a two-toned shell that is brown above the periphery and white below, while M. nebulosa has a conoidal, depressed, shell that is bluntly angulated at the periphery.

Macrochlamys aurantia Pholyotha & Panha, new species (Figs. 2A, 3A, B, 4A–E, 6A–C) Material examined. Holotype (Fig. 3A; shell height 8.0 mm, shell width 14.0 mm, aperture height 6.0 mm, aperture width 7.2 mm, 5⅝ whorls) (CUMZ 7101), limestone outcrop at Wat Uthum Phon Wanaram (Temple), Huai Kayeng Village, Thong Pha Phum District, Kanchanaburi Province, Thailand, 14°41′52.6″N, 98°31′32.3″E. Paratypes: three shells (Fig. 3B; shell height 8.0 mm, shell width 13.9 mm, aperture height 6.5 mm, aperture width 7.1 mm, 5⅞ whorls) (CUMZ 7102), 12 specimens (CUMZ 7103), one shell (NHMUK), one shell (ZRC.MOL.13771), same data as holotype. Etymology. The specific name “ aurantia ” is from Latin “ aurantium ” meaning “orange”, and refers to the prominent orange or reddish orange posterior part of its body. Description. Shell medium-sized (Fig. 3A, B; shell height up to 8.2 mm; shell width up to 14.0 mm), dextral, comparatively depressed, thin but not fragile, semi-translucent, shiny and yellowish brown in colour. Shell surface smooth with fine growth lines. Embryonic shell small, about 2½ whorls with smooth surface. Whorls 5–6, regularly increasing. Suture wide and deeply channelled. Spire depressed, apex little raised, spire angle about 152–156°. Last whorl large, periphery rounded. Aperture oval-lunate, open obliquely, lip simple. Columellar edge slightly thickened and a little reflected over the narrowly open umbilicus. Genital organs. Atrium (at) short. Penis prolonged, slightly enlarged and cylindrical-shaped. Distally cylindrical and corresponding to penial verge. Penial caecum (pc) slightly prolonged. Epiphallus (e) slender tube, about two times length of penis. Epiphallic caecum (ec) coiled about one circle, located at middle of epiphallus and attached with thick penial retractor muscle (prm). Flagellum (fl) large, irregular coiled and length around half of epiphallus length. Vas deference (vd) slim tube connected between distal end of epiphallus and free oviduct (Fig. 4A). Internal wall of penis with very small and oblique wrinkled penial pilasters (pp). Penial verge (pv) small, thick and located at distal end of penis (Fig. 4B). Vagina (v) long, cylindrical-shape, about same length as penis. Dart apparatus (da) small, cylindrical-shape and situated at proximal end of vagina. Gametolytic sac (gs) prolonged and bulbous. Gametolytic duct (gd) long and cylindrical (two spermatophores in Fig. 4A). Free oviduct (fo) a long slender tube, proximal end encircled with thick brownish tissue. Oviduct (ov) large lobules, with prostate gland (pg) running alongside oviduct (Fig. 4A). Spermatophore long, needle-shape and translucent (Fig. 4C–E). Head filament (hf) short, gradually thinning to terminal point (Fig. 4D). Sperm sac (ss) a cylindrical capsule, containing sperm mass. Tail filament (tf) very long and cylindrical. Region close to sperm sac bearing three spines. First one dichotomous and split into two short spines, second one curved, located on same base as previous, third one simple, long and curved (Fig. 4D). Region furthest from sperm sac with small spine cluster near tip (Fig. 4E). Out of 10 specimens examined, seven contain one spermatophore and three contain two spermatophores in gametolytic organs. Radula. Teeth arranged in a U-shape, with about 103 teeth in each row with formula (48-(12-10)-1-(10-11)-54). Central tooth symmetrical, tricuspid with large and lanceolate mesocone, ectocones small and pointed cusps. Lateral teeth asymmetrical tricuspid. Endocone small, located near tip, mesocone large, triangular with pointed cusp. Ectocone larger than edocone and located near tooth base. Marginal teeth start around tooth number 10–12, obliquely bicuspid, elongate and narrower than others. Endocone large, ectocone smaller with pointed cusp (Fig. 6A–C). External features. Animal with reticulated skin. Head to eye stalks dark grey, body and tail deep yellow-orange. Caudal foss (cf) long and narrow. Caudal horn (ch) raised, large and greyish-orange. Mantle edge (shell lobes and dorsal lobes) well developed, dark to bright orange in colour. Shell lobes large and long. Right shell lobe (rsl) larger and longer than left shell lobe (lsl). Dorsal lobes large and broad. Right dorsal lobe (rdl) larger than both anterior left dorsal lobe (ant-ldl) and posterior left dorsal lobe (post-ldl). Snails secrete light orange slime when disturbed (Fig. 2A). Distribution and habitat. Macrochlamys aurantia new species was usually found on the surface of limestone walls and in rock crevices. Some individuals were encountered creeping on the leaves of a bush or tree trunk close to the limestone outcrop during our surveys. This species is probably locally endemic, and is currently known only from the type locality, where the population density is rather abundant. Remarks. Macrochlamys aurantia new species can be distinguished by the depressed spire, yellowish colour, large and rounded last whorl, and a wide and deep-channelled suture. The genitalia have long penis and vagina, one circle of coiled epiphallic caecum and a small dart apparatus located at the base of the vagina opposite the penis. Spermatophore has three spines at the proximal end and a cluster of small spines at the distal end of the tail filament. This new species can be distinguished from M. consepta (Benson, 1860) and M. chaos Blanford, 1905 from Myanmar by its depressed shell with a wide deeply impressed suture, and broad last whorl and aperture. In contrast, M. consepta has an almost flat shell with shallow suture, and the last whorl and aperture are not much broader. Macrochlamys chaos has a conoidly depressed shell with shallow suture, and narrow last whorl and aperture. In addition, this new species can be distinguished from all other known species by its spermatophore with three spines at the proximal end, and the cluster of small spines at the distal end of the tail filament.