Burmochlamys moulmeinica Pholyotha & Panha, 2022

Pholyotha, Arthit, Sutcharit, Chirasak, Lin, Aung & Panha, Somsak, 2022, Uncovering local endemism from southeastern Myanmar: description of the new karst-associated terrestrial snail genus Burmochlamys (Eupulmonata, Helicarionidae), ZooKeys 1110, pp. 1-37 : 1

Burmochlamys moulmeinica Pholyotha & Panha sp. nov.

Figs 1 , 2D , 4A , 5E , 7E, F , 10B , 13A-C , 15A

Material examined.

Type material. Holotype: CUMZ 14216 (Fig. 7E ; width 5.0 mm, height 4.2 mm). Paratypes: Same locality as holotype: CUMZ 14217 (Fig. 7F ; width 4.5 mm, height 4.2 mm), NHMUK (two shells).

Type locality.

Limestone outcrop at Lun Nya Pagoda, Hpa-An, Kayin State, Myanmar (16°44'53.8"N, 97°47'09.1"E).

Diagnosis.

Shell globose and pale to dark brownish. Animal greyish with five mantle extensions. Genitalia with very short epiphallic caecum attached by a thin penial retractor muscle and rather short vagina.

Description.

Shell (Figs 7E, F , 13A-C ). Shell globose, small (width up to 5.0 mm, height up to 4.2 mm), rather thin, and semi-translucent. Colour pale to dark brownish. Protoconch and teleoconch surface with similar sculpture. Surface of body whorl with distinct spiral furrows at regular intervals, cut by distinctly undulating radial lines (Fig. 13A-C ). Whorls 6- 6½, increasing regularly; suture shallowly impressed; spire much elevated; last whorl well-rounded. Aperture obliquely crescent-shaped; peristome simple. Columellar margin simple, slightly reflected near umbilicus. Umbilicus open, narrow, and deep.

Genital organs (Fig. 10B ). Atrium (at) very short. Penis (p) moderate, cylindrical and with thin penial sheath. Epiphallus (e1+e2) ca. half of penis length; e1 cylindrical and smaller diameter smaller than penis and e2; e2 bulbous and ca. half of e1 length. Epiphallic caecum (ec) very short, bulbous, and with thin penial retractor muscle (prm) attached at tip. Vas deferens (vd) thin tube. Dart apparatus large, long cylindrical, and located on atrium at vagina and penis junction. Vagina (v) rather short, cylindrical. Gametolytic sac (gs) bulbous; gametolytic duct (gd) cylindrical, rather short, ca. half of penis length. Free oviduct (fo) ca. two-third of penis length, cylindrical, and encircled with thick tissue near vagina.

Radula (Fig. 15A ). Resembles B. cassidula . Teeth arranged in wide U-shaped rows with each row consisting of ~ 50 teeth; central tooth monocuspid, large and ovate spatulate shape with both sides of its base attached by two triangular-shaped plates; laterals and marginals not differentiated, monocuspid, large spatulate shape then gradually become narrower, elongate, smaller, and rather more pointed cups outwards, and attached at base and on outer side by one smaller triangular-shaped plate.

External appearance (Figs 4A , 5E ). Living animal with reticulated skin, grey body, slightly lighter on foot sole and darker colour on caudal horn. Mantle extensions with three dorsal lobes and two shell lobes; same colour as body.

Etymology.

The specific epithet moulmeinica is a noun in reference to the historical name of Mawlamyine city, pertaining to the Salween River basin, where the type locality is situated.

Distribution.

Burmochlamys moulmeinica sp. nov. is endemic to a small limestone area at Lun Nya Pagoda in Myanmar (Figs 1 , 2D ). The isolated limestone is surrounded by paddy fields that are temporarily flooded during the monsoon season (Fig. 2D ). In addition, this new species is also sympatric with the limestone karst-restricted species, Sophina pisinna Sutcharit & Panha, 2020.

Remarks.

Burmochlamys moulmeinica sp. nov. is similar to B. poongee in shell morphology but can be differentiated by genitalia. This new species has a relatively short epiphallus and a rather short at the base of dart apparatus, whereas B. poongee has a slender and longer epiphallus and a very long and small at the base of dart apparatus.

Figures

Figure 1. Map of the Salween River basin (known as Thanlwin River) in the southeastern Myanmar showing the sampling sites. Coloured triangles indicate the localities recorded for each Burmochlamys species. White circles indicate the localities recorded for Sophina species. White squares indicate the sampling localities with no records of both Sophina and Burmochlamys species.

Figure 2. Habitat of some species of Burmochlamys gen. nov. in the karst basin of Hpa-An, Kayin State, Myanmar. A type locality of B. fasciola sp. nov. at Bardai Mountain and microhabitat structure of the karst wall B newly discovered locality of B. poongee at Kaw Ka Thaung Cave C type locality of B. albida sp. nov. at Waiponla Monastery D type locality of B. moulmeinica sp. nov. at Lun Nya Pagoda E type locality of B. versicolor sp. nov. at Bayin Nyi Cave. Photos by Ruttapon Srisonchai.

Figure 4. A adult of B. moulmeinica sp. nov. while climbing slowly on the karst wall after raining at Lun Nya Pagoda B mating pairs of B. versicolor sp. nov. on the karst wall at Bayin Nyi Cave C B. versicolor sp. nov. eaten by the carnivorous snail Carinartemis sp. on the karst wall at Bayin Nyi Cave D B. cassidula eaten by the carnivorous snail Haploptychius sp. on the karst wall at Kaw Gon Cave.

Figure 5. Living snails of Burmochlamys species A B. fasciola sp. nov. paratype CUMZ 14214 showing left and right lateral views B B. cassidula specimen CUMZ 14209 C B. poongee specimen CUMZ 14210 D B. albida sp. nov. paratype CUMZ 14212 E B. moulmeinica sp. nov. paratype CUMZ 14217 F B. versicolor sp. nov. paratype CUMZ 14219 G B. whitteni sp. nov. paratype CUMZ 14222.

Figure 7. Shells of Burmochlamys species A, B B. albida sp. nov. A holotype CUMZ 14211, and D paratype CUMZ 14212 C, D B. fasciola sp. nov. C holotype CUMZ 14213 D paratype CUMZ 14214 E, F B. moulmeinica sp. nov. E holotype CUMZ 14216 F paratype CUMZ 14217.

Figure 10. General view of the genital system of Burmochlamys species A B. fasciola sp. nov. paratype CUMZ 14214 B B. moulmeinica sp. nov. paratype CUMZ 14217 C B. versicolor sp. nov. paratype CUMZ 14219. White arrow indicates the end of the penis. Yellow arrow indicates the solid at the tip of dart apparatus. Red-dotted line indicates vas deferens missing.

Figure 13. Representative SEM images of the shell of Burmochlamys species A-C B. moulmeinica sp. nov. paratype CUMZ 14217 A protoconch B body whorl C zoom-in view of body whorl. D-F B. versicolor sp. nov. paratype CUMZ 14219 D protoconch E body whorl F zoom-in view of body whorl G-I B. whitteni sp. nov. paratype CUMZ 14222 G protoconch H body whorl I zoom-in view of body whorl.

Figure 15. Representative SEM images of the radula of Burmochlamys species A B. moulmeinica sp. nov. paratype CUMZ 14217 B B. versicolor sp. nov. paratype CUMZ 14219 C B. whitteni sp. nov. paratype CUMZ 14222. Central tooth indicated by ' C'; yellow colour indicates central tooth row.