Sarika dugasti (Morlet, 1891)

Pholyotha, Arthit, Sutcharit, Chirasak, Tongkerd, Piyoros & Panha, Somsak, 2020, Integrative taxonomic revision of the land snail genus Sarika Godwin-Austen, 1907 in Thailand, with descriptions of nine new species (Eupulmonata, Ariophantidae), ZooKeys 976, pp. 1-100 : 1

Sarika dugasti (Morlet, 1891) Figs 1 , 44 , 45A , 46A, B , 47A, B , 48A

Macrochlamys dugasti Morlet, 1891a: 25, 26. Type locality: “forêts des bords du Ménam-Pinh, Laos occidental" [forest edges of Ping River, Thailand]; Fischer-Piette 1950: 159; Panha 1996: 34; Hemmen and Hemmen 2001: 44.

Ariophanta (Macrochlamys) dugasti : Morlet 1891b: 231, 239, 240, pl. 5, figs 1, 1a; Fischer 1891: 20.

Nanina (Macrochlamys) dugasti : Fischer and Dautzenberg 1904: 395.

Sarika dugasti : Tomlin 1929: 16. Maneevong 2000: 31, fig. 4-3; Sutcharit and Panha 2008: 96; Schileyko 2011: 34. Inkhavilay et al. 2019: 149, fig. 59f; Pholyotha et al. 2020c: 19, fig. 9f.

Type material.

Syntype MNHN-IM-2000-27884 (one shell; Fig. 46A ) from Forêts des bords du Ménam-Pinh, Laos occidental [forest edges of Ping River, Thailand]. Possible syntype NHMUK 1893.12.8.31 (one shell).

Other material examined.

Myanmar. Phaboo, Salwin Valley, Burma: NHMUK 1891.3.17.559 60 (two shells). Moulmein: NHMUK 1887.06.1.1 (two shells). Thailand. Siam: NHMUK 1903.7.1.100, NHMUK 1901.1.06.38 (specimen figured in Blanford and Godwin-Austen 1908: Fig. 48 ), SMF 90841/2 (two shells). Thailand-Western. Wat Tham Inthanin, Mae Sot, Tak, 16°46'01.4"N, 98°40'21.5"E: CUMZ 7567. Limestone outcrop in Mae Sot, Mae Sot, Tak, 16°45'40.8"N, 98°43'08.1"E: CUMZ 7568, 7569. Chao Por Phawo Shrine, Mae Sot, Tak, 16°46'16.9"N, 98°41'09.1"E: CUMZ 7571, 7572, 7573, 7574. Limestone outcrop in Tha Song Yang, Tha Song Yang, Tak, 17°27'11.8"N, 98°10'39.2"E: CUMZ 7570. Ban Nam Ok Hu, Tha Song Yang, Tak, 17°07'54.4"N, 98°23'41.5"E: CUMZ 7575. Limestone outcrop in Umphang, Umphang Tak, 16°00'53.4"N, 98°56'47.7"E: CUMZ 7576. Thailand-Central. Pitsunaloke, Siam: NHMUK 1903.2.4.82-84 (four shells). Limestone area near Huai Kha Khaeng, Lan Sak, Uthai Thani, 15°36'31.1"N, 99°19'15.0"E: CUMZ 7543. Limestone outcrop in Phran Kratai, Phran Kratai, Kamphaeng Phet, 16°40'40.1"N, 99°32'27.1"E: CUMZ 7541. Wat Khao Huai Lung, Banphot Phisai, Nakhon Sawan, 15°55'30.2"N, 99°52'28.9"E: CUMZ 7564. Wat Thep Sathaporn, Banphot Phisai, Nakhon Sawan, 15°54'48.7"N, 99°53'04.0"E: CUMZ 7565, 7566. Tham Yok, Ban Dan Lan Hoi, Sukhothai, 17°08'15.9"N, 99°33'00.5"E: CUMZ 7542 (Fig. 46B ). Limestone outcrop in Na Choeng Khiri, Khiri Mat, Sukhothai, 16°52'38.7"N, 99°41'35.1"E: CUMZ 7557. Tham Lom-Tham Wang, Si Samrong, Sukhothai, 17°13'30.3"N, 99°31'53.0"E: CUMZ 7558, 7559, 7560. Wat Tham Rakhang, Si Samrong, Sukhothai, 17°09'54.2"N, 99°33'36.2"E: CUMZ 7561, 7562, 7563. Thailand-Northern. Lampun, Siam: SMF 298588/2 (two shells). Lampoon, Siam: NHMUK MacAndrew Coll. Acc. No. 1563 (three shells), NHMUK Kennard Coll. Acc. No. 1824 (one shell), NHMUK ex. 392 (five shells). Tham Luang Pha Wiang, Ban Hong, Lamphun, 18°13'18.7"N, 98°51'27.7"E: CUMZ 7551, 7552, 7553, 7554, 7577. Erawan Cave, Pa Sang, Lamphun, 18°19'38.4"N, 98°52'17.9"E: CUMZ 7555, 7556. Wat Tham Pha Ngam, Mae Phrik, Lampang, 17°28'49.6"N, 99°10'05.3"E: CUMZ 7549. Wat Tham Suk Kasem Sawan, Thoen, Lampang, 17°42'40.0"N, 99°12'25.2"E: CUMZ 7550. Wachirathan Waterfall, Chom Thong, Chiang Mai, 18°32'31.2"N, 98°35'53.7"E: CUMZ 7544. Borichinda Cave, Chom Thong, Chiang Mai, 18°30'02.8"N, 98°40'20.4"E: CUMZ 7545, 7546. Wat Tham Tong, Chom Thong, Chiang Mai, 18°15'19.8"N, 98°34'48.0"E: CUMZ 7547. Wat Tham Muang On, Mae On, Chiang Mai, 18°47'46.3"N, 99°14'05.5"E: CUMZ 7548.

Diagnosis.

Shell medium, globosely depressed, pale to dark brown with well-rounded body whorl. Animal with greyish body and five mantle lobes. Genitalia with a long straight epiphallic caecum and long pseudo-verge. Inner penial sculpture with small cuboidal pilasters in proximal part, then reticulated pilasters in the middle, and larger cuboidal pilasters in distal end.

Description.

Shell. Shell globosely depressed, medium size (shell width up to 17.2 mm, shell height up to 10.5 mm), and rather thin. Shell surface smooth and shining; shell colour very pale to dark brown. Whorls 6½-7½, increasing regularly; body whorl large and well rounded. Spire much elevated; suture impressed. Aperture crescent-shaped and obliquely opened. Peristome simple and slightly thickened. Columellar margin simple and slightly reflected near umbilicus. Umbilicus narrowly opened (Fig. 46A, B ).

Genital organs. Atrium short. Penis long cylindrical with thin penial sheath covering penis. Proximal penis rather slender; distal penis enlarged with pseudo-verge inside. Inner sculpture of penis proximally with very finely longitudinal penial pilasters to nearly smooth surface, then transformed to small cuboidal and reticulated pilaster in middle and modified to larger cuboidal pilasters at distal end. Pseudo-verge elongate conic and approximately one-third of penis length. Epiphallus cylindrical, and narrower than distal penis. Epiphallic caecum very long, straight, and same diameter as epiphallus. Penial retractor muscle thin and attached at tip of epiphallic caecum. Flagellum long, slender, and approximately as long as penis. Vas deferens thin tube connecting distal epiphallus and free oviduct (Fig. 47A, B ).

Vagina short and approximately one-third of penis length. Dart apparatus large, long cylindrical, and located on atrium at vagina and penis junction. Gametolytic organ (sac and duct) small and long cylindrical tube. Free oviduct cylindrical, approximately as long as vagina, and proximal end encircled with thick tissue (Fig. 47A ).

Radula . Teeth with half row formula: 1-(11-12)-47. Central tooth symmetrical tricuspid; lateral teeth asymmetrical tricuspid; marginal teeth elongate bicuspid. Marginal teeth starting at approximately row number 11 or 12 (Fig. 48A ).

External features. Animal with reticulated skin, greyish body, slightly pale colour on foot sole and darker colour on caudal horn. Mantle edge well developed with three dorsal lobes and two shell lobes, and similar colour to body (Fig. 45A ).

Distribution.

Sarika dugasti occurs in central, north and western Thailand along the Tenasserim Ranges (Fig. 44 ) and the Salween Valley, east of the Dawna Ranges in Myanmar ( Blanford and Godwin-Austen 1908; Pholyotha et al. 2020c). However, the literature records from Laos, Nepal and Vietnam ( Schileyko 2011; Inkahvilay et al. 2019) are still uncertain.

COI analysis.

The ML and BI analyses revealed that the individuals of S. dugasti (n = 3) formed a monophyletic group with good support (Fig. 1 ; BS = 91%, PP = 1). The mean intraspecific genetic distance of S. dugasti was 3.7% (Table 2 ).

Remarks.

Sarika dugasti can be distinguished from all other known Sarika species by having a dome-shaped shell with narrow aperture and genitalia with a very long epiphallic caecum and long pseudo-verge. Other Sarika species tend to have a flattened to depressed shell with a wide aperture and genitalia without penial verge. Although we surveyed during the wet season, only immature snails were collected, and so the radula and genitalia of sub-adult specimens are illustrated here.

Figures

Figure 1. Maximum likelihood tree showing the relationships among species of Sarika based on the mitochondrial COI gene sequences. Numbers by the nodes are the ML bootstrap values (left) and Bayesian posterior probabilities (right); shown only for the nodes supported by ML or BI (≥ 70 % and ≥ 0.95). Each clade colour refers to a genus.

Figure 44. Geographic distribution of Sarika dugasti and S. solemi sp. nov. based on the specimens examined herein.

Figure 45. Living snails of Group III: Sarika dugasti group. A Sarika dugasti specimen CUMZ 7563 and B S. solemi sp. nov. paratype CUMZ 7298. Not to scale.

Figure 46. Shells of Group III: Sarika dugasti group. A, B Sarika dugasti A syntype MNHN-IM- 2000 - 27884 and B specimen CUMZ 7542, C-F S. solemi sp. nov. C holotype CUMZ 7297 D paratype CUMZ 7298, and E, F specimen CUMZ 7503.

Figure 47. Genitalia. A, B Sarika dugasti specimen CUMZ 7542 A general view of the genital system and B internal structure of the penis C, D S. solemi sp. nov. paratype CUMZ 7298 C general view of the genital system and D internal structure of the penis. White arrowheads indicate the ends of the penes.

Figure 48. Representative SEM images of the radula. A Sarika dugasti specimen CUMZ 7574 and B S. solemi sp. nov. paratype CUMZ 7298. Central tooth indicated by ' C'; Yellow colour indicates lateral teeth with the transition to marginal teeth.