Pincerna vanbuensis (Bavay & Dautzenberg, 1900)

Sang, Do Duc & Son, Nguyen Thanh, 2022, The land snail genus Pincerna Preston, 1907 (Gastropoda: Alycaeidae) from Vietnam and Laos, with description of a new species, Raffles Bulletin of Zoology 70, pp. 364-375 : 369-372

Pincerna vanbuensis (Bavay & Dautzenberg, 1900)

( Figs. 1 , 3A–E , 6E ; Tables 1, 2)

Alycaeus (Dioryx) vanbuensis Bavay & Dautzenberg, 1900a: 120 (type locality: Van-Bu = SƠn La Province, Vietnam).

Alycaeus (Dioryx) vanbuensis – Bavay & Dautzenberg, 1900b: 455, pl. 11, figs. 19–21.

Dioryx vanbuensis – Kobelt, 1902: 340; Do et al., 2015: 120, fig. 2C.

Alycaeus vanbuensis – Fischer & Dautzenberg, 1904: 432; PállGergely et al., 2017: 10, fig. 3C; Inkhavilay et al., 2019: 13 , figs 4C–E.

Pincerna vanbuensis – Páll-Gergely et al., 2020: 184.

Material examined. Type material. Tonkin, Van-Bu, leg. Dr. R. Bavay, MNHN-IM-2000-31798 (syntype) ( Figs. 3A , 6E ); Van Bu, Tonkin, RBINS 525448 (paratypes) .

Additional material examined. ZMHU/ 20 , Vietnam, SƠn La Province, Thu ận Châu District, Co Mạ Commune , Copia Nature Reserve , steep limestone slope with dense disturbed vegetation, 21°21′25″N, 103°31′14″E, 1239 m a.s.l., col. D.S. Do & T.H. Nguyen , 08 June 2013 ; ZMHU/ 11 , Vietnam, SƠn La Province, Mai SƠn District , MƯ ờng Bằng Commune, Nà Hoi Village , limestone hill with degraded regrowth, 21°18′11″N, 104°02′16″E, 779 m a.s.l., col. D.S. Do & T.L. Nguyen , 22 November 2013 ; ZMHU/ 23 ( Figs. 3B, E ), Vietnam, SƠn La Province, Thu ận Châu District, Bon Ph ặng Commune , Đốm HƯ Ợn Village , 21°22′23″N, 103°46′19″E, 605 m a.s.l, limestone karst, col. D.S. Do & T.D. Luong , 20 August 2013 ; ZMHU/ 5 , Vietnam, SƠn La Province, Yên Châu District, Yên SƠn Commune , Chi Đảy Cave , primary forest on limestone, 21°08′30″N, 104°10′29″E, 815 m a.s.l., col. D.S. Do & X.H. Nguyen, 02 September 2017 ; ZMHU/ 4 , Vietnam, Hòa Bình Province, Mai Châu District, Tân SƠn Commune , Bó Liêm Village , under rocks in old secondary forest, 20°10′29″N, 104°58′17″E, 553 m a.s.l., col. D.S. Do & C. Vilachark, 07 January 2018 ; ZMHU/ 9 , Vietnam, Ninh Bình Province, Cúc PhƯƠng National Park , limestone outcrops in shale bedrock of primary forest, 20°21′13″N, 105°54′22″E, 297 m, col. D.S. Do & T.L. Nguyen , 19 August 2016 ; ZMHU/ 26 ( Fig. 3C ), Laos, Xieng Khouang Province, Khoune District, Nam Phan Commune, Pa Kha Village , limestone area near village, 19°31′59″N, 103°31′01″E, col. C. Vilachark, 26 July 2018 ; ZMHU/ 18 ( Fig. 3D ), Laos, Houaphanh Province, Xiengkho District, Na Tong Village , limestone hills, col. P.S.L. Ti Khun, 20 August 2018 .

Diagnosis. Pincerna vanbuensis is characterised by a small sized, globular shell with irregular, clearly visible ribs on R3.

Distribution. This species is known from Vietnam (SƠn La, Hòa Bình, Quang Ninh, Ninh Binh Provinces) and Laos (Luang Namtha and Luang Phrabang Provinces) ( Vermeulen & Maassen, 2003; Inkhavilay et al., 2019).

Remarks. Its type locality Van-bu most probably refers to “Vạn Bú” Province, which was established in 1895 and remained until 1904. This species clearly differs from P. anceyi and P. costulosa because its R2 is relatively long, while its R1 possesses clearly visible and regular spaced ribs. The operculum of three specimens have been examined. The inner surface of operculum is smooth, glossy and has no central nipple. The outer surface is relatively flat, with indistinct appressed multilamellae. Pincerna vanbuensis is a very variable species in terms of shell size, sculpture of R1 and R3, number of R2 ribs and the extension of the columella (see Tables 1, 2).

Figures

Fig. 1. Distribution of Pincerna species in Vietnam and Laos. Triangle: Pincerna anceyi; Grey circle: Pincerna costulosus; Black circles: Pincerna mouhoti; Squares: Pincerna vanbuensis; Star: Pincerna clausa, new species. The localities are detailed in Table 1.

Fig. 3. Shells (apertural view, dorsal view, ventral view, and side view) and operculum (outer surface, inner surface, and side view) of Pincerna vanbuensis (Bavay & Dautzenberg, 1900). A, syntype MNHN-IM-2000-31798; B, E, specimen from Thuận Châu, SƠn La, Vietnam, ZMHU; C, specimen from Khoune, Xieng Khouang, Laos, ZMHU; D, specimen from Xiengkho, Houaphanh, Laos, ZMHU.

Fig. 6. Synoptic view of Vietnamese and Laos Pincerna species. A, MNHN-IM-2000-31797; B, NHMUK 20170120; C, MNHN- IM-2000-31786; D, VNMN-IZ 002.304; E, MNHN-IM-2000-31798.