Serina Gredler (Gastropoda, Stylommatophora: Enidae), the continuous-peristomed mountain snails endemic to the eastern slope of the Qinghai-Xizang Plateau Author Wu, Min Author Xu, Qin text Zootaxa 2013 3620 1 43 66 journal article 10.11646/zootaxa.3620.1.2 60ae7d68-88b7-4da4-acae-6e4cda073ea0 1175-5326 283400 3870AC9F-A4EE-4E36-86C7-E1D6967A2A2E 4. Serina prostoma (Ancey, 1884) Figs. 1 , 2 K– O , 4, 9, 10; Tables 1–3 , 6 Bulimus prostomus Ancey, 1884: 395 . Bulimus prostomus var. leucochila Ancey, 1884: 396 ( Type locality: Yerkalo). Buliminus ( Serina ) prostoma— Kobelt, 1902: 933, pl. 131, figs. 8–10. Buliminus ( Holcauchen ) tubios Annandale, 1924: 394 , pl.16, figs. 6, 6a ( Type locality: Gorges in the Yangtsa district of the Upper Mekong). Ena ( Serina ) prostomus— Yen, 1938: 442. Serina prostoma –Yen, 1939: 87, pl. 8, fig. 24. Yen, 1942: 255. Chen, Zhou, Luo & Zhang, 2003: 442. Serina deqenensis Chen, Zhou & Luo, 2003: 444 , figs. 1–4 ( Type locality: Meilishi Town). Type locality. Tsé-kou (Xizang Autonomous Region). Material examined. HBUMM-04287: 16 fma (all measured and 1 dissected) and 1 juv. ; Deqing County, Yunnan, 2003–VIII–28 , colln. KS. HBUMM-04296: 171 fma (20 measured and 2 dissected) and 15 juv. ; eastern bank of Lancangjiang River, western to Yanjing Town, Mangkang County, Xizang Autonomous Region, 2583 m a.s.l., 29º02ʹ0 0.0ʹ N, 098º36ʹ22.9ʹ E), red Sandstone + sandy loam, bushes and grass, 2002–VII–11 , colln. AW & MW ( Fig. 10 in this work). NHM-1920.8.10.38 Reg.: 1 full matured shell. Mekong, Thibet. NHM- 1912.6.27.69–71 Reg.: 3 fms, all measured. Mekong (imprecise locality), Upper Yangtze, Tibet. NHM: 1 fms. Mekong, Ancey, Thibet. Trechmann Acc. No. 2176. NHM-1923.5.24.17–36: paratypes of Buliminus ( Holcauchen ) tubios , numerous fms; 5 measured. Gorge of Mekong above Yangtsa; alt. 2134 m to 2286 m , arid. SMF-42050: Paratype , measured. Dshy-kow (unrecognised locality belonged to Xizang Autonomous Region today), Szechwan, China (Ancey in Slg. Möllendorff—see Yen, 1939: 87). Distribution. Xizang Autonomous Region ( type locality, Mangkang, Mekong), Yunnan (Deqing). Diagnosis. Shell with the most swollen part occurred at penultimate whorl. Whorls with a narrow, defined zone below the suture. Last whorl descending in front; straight or concaved at periphery. Aperture not duplicate; separated from body whorl; not armed. Shell. Turrited, or fusiform; dextral; apically more or less abruptly pointed; opaque (except apical 4 whorls slightly semitransparent); more or less glossy; with the most swollen part occurred at penultimate whorl; height 11.2–13.3–14.9, diameter major 3.4–4.5–5.5, ratio of height /diameter major 2.53–2.96–3.50. Growth lines fine and clear. Whorls 7 7/8–8 1/2–9 1/4, convex (except ultimate two whorls); with a narrow, defined zone below the suture. Embryonic shell 1 5/8–1 7/8+–2 1/8 whorls. Postnuclear whorls smooth. Last whorl slightly descending in front; slightly concaved or straight at periphery; abaperturally with a rugate region with crowded and/or thickened growthlinelike folds. Aperture almost in a plane and straight; ovate; rather oblique; separated from body whorl; not armed; height 3.2–3.9–4.5, width 2.8–3.5–3.9, ratio of shell height /apertural height 2.99–3.41–4.02. Aperture not duplicate. Peristome and parietal callus almost completely fusing except for a channel at upper insertion of peristome. Reflexed part of peristome straight and not curved backward. Abapertural peripheral depression on body whorl spirally extending for ca. 1 whorl. Columellar margin reflexed. Columella oblique. Umbilicus widely open. Apical four whorls reddish brown; subsequent whorls white with a few streaks in light brown; bandless. Aperture white. Apical whorls differently tinted. Measured specimens: NHM- 1912.6.27.69-71, NHM- 1923.5.24.17-36, HBUMM-04287, HBUMM-04296, SMF-42050: 45 shells. FIGURE 4. Serina prostoma (Ancey, 1884) . A. General view of genitalia, HBUMM-04287–specimen 1, Deqing. B. internal view of penis, HBUMM-04287–specimen 1, Deqing. C. General view of genitalia, HBUMM-04296–specimen 21, Yanjing. D. internal view of penis, HBUMM-04296–specimen 21, Yanjing. Genitalia. Vas deferens proximally swollen; entering epiphallus laterally with distinct demarcation. Epiphallus short; straight; cylindrical and of uniform thickness. Epiphallic caecum blunt apically; located in middle of epiphallus. Flagellum short; tubular; proximally normal; with tip blunt. Penis clavate; evenly thick; laterally entering epiphallus; thin-walled. Longitudinal pilasters more than two; not fused at epiphallic pore; forming 2 Vshaped structures. V-shaped pilaster with proximal free end approaching at penial retractor insertion; without papilla formed by fused distal pilasters. Penial process absent. Penial appendix short; branched off from penis at some distance from atrium; with A-1 fused with A-2, A-3 distinct, and A-4 fused with A-5. A-1 long; without verge toward penial chamber. A-2 internally with longitudinal pilasters; near A-3 internally with a ring of papilla. A-3 opening into A-2 by a long needle-like papilla. A-5 short; straight. Penial retractor biramous; with arms arising from diaphragm separately, or with arms arising from diaphragm closed to each other; with penial branch attaching to proxmal penis; with appendical branch attaching to A-1+A-2. Atrium short; with weak atrial retractor. Free oviduct moderately long; subequal to vagina in length. Vagina moderately long; not swollen; straight; unpigmented. Bursa copulatrix duct moderately long; proximally straight. Bursa copulatrix in normal size; well defined; with stalk; without apical ligament; with long neck. Diverticle longer than or subequal to reservoir in length; unexpanded. Bursa copulatrix and diverticle distinguishable; forked more distally from their base. Measurement of genitalia: See Table 2 (HBUMM-04287–specimen 1 and HBUMM-04296–specimen 21 are measured). Taxonomic remarks. Buliminus ( Holcauchen ) tubios is a obvious synonym of Serina prostoma . Bulimus prostomus leucochila , was established by the diagnosis “ Testa minore, exiliore, pallid caerulea; apice corneo; aperture intus subcornea; peristomate albido;-alt. 12 millim ” (Ancey 1884). Such shell size and main coloration feature is also observed in the specimens HBUMM-04287 of which 16 shells have the white aperture and with shell height range 11.2–12.7–14.0 mm. Therefore it is insufficient to be distinguished from S . prostoma . Since no reliable diagnosis of Serina deqenensis was given by Chen, et al. (2003), this taxon is here regarded as a synonym of S. prostoma . Ecological remarks. This species dwells in the very arid environment near the bank of Langcangjiang River (Yanjing) ( Fig. 10 A). In the same season, as observed by the first author at the locality situated nearby, another enid snail Holcauchen sp. inhabits a relatively wet environment characterized by the rich coverage of periodically hydrophilous moss, algae and lichen. This slightly indicates there might be different habitat preference by these two genera/species.