Serina subser Gredler, 1898

Wu, Min & Xu, Qin, 2013, Serina Gredler (Gastropoda, Stylommatophora: Enidae), the continuous-peristomed mountain snails endemic to the eastern slope of the Qinghai-Xizang Plateau, Zootaxa 3620 (1), pp. 43-66 : 55-56

6. Serina subser Gredler, 1898

Figs. 1 , 5 C–E, 6A-D; Tables 1–3 , 6 Serina subser Gredler, 1898a: 12 , T. F. 9.

Serina subser— Gredler, 1898b: 107; Yen, 1939: 87, pl. 8, fig. 18; Yen, 1942: 255; Zilch, 1974: 214; Chen, Zhou, Luo & Zhang, 2003: 442 (sunser is a spelling error).

Buliminus (Serina) subser— Möllendorff, 1901: 360, pl. 16, figs. 8–10; Wiegmann, 1901: 266, pl. 11, figs. 71–75; Kobelt, 1902: 862, pl. 123, figs. 8–10.

Type locality. Tan-tchang (Dangchang in modern spelling. S Gansu).

Material examined. HBUMM-00287: 15 fma (all measured and 1 dissected) and 2 juv.; Nanyu Village, Zhouqu (33º48ʹN, 104º18ʹE), Gansu, 2004–IV–30, colln. MW. HBUMM-05392: 213 fma (20 measrued and 1 dissected) and 18 juv.; southern town of Lixian County, Gansu, from site 1350 m a.s.l., 34°09'14.0''N, 105°07'40.5''Eto site 1373 m a.s.l., 34°10'58.4''N, 105°10'14.2''E. HBUMM-05603: numerous fma; southern slope of Nanshan, Wudu, Gansu, 2006–IX–30, colln. JL & WZ. HBUMM-05640: 110 fma (20 measured and 1 dissected) and 7 juv.; Jiaogong, from site 1137 m a.s.l., 33°34'21.7''N, 104°39'00.3''E to site 1151 m a.s.l., 33°34'28.3''N, 104°39'10.7''E, broken limestone, Gansu, 2006–X–2, colln. JL & WZ. HBUMM-05675: 6 fma (all measured and 2 dissected); eastern bank of Lianghekou, Zhouqu, Gansu, 2006–X–2, colln. JL & WZ. HBUMM- 05648: 5 fma (all measured) and 2 juv., information as HBUMM-05640. HBUMM-05709: 2 fma (all meatured); Guanting, limestone hills, from site 1358 m a.s.l., 33°47'37.3''N, 104°31'48.0''E to site 1395 m a.s.l., 33°49'54.3''N, 104°32'12.0''E. HBUMM-05796: 7 fma (all measured), other information as HBUMM-05640 (?). NHM- 1902.5.13.23–24: 2 fms; Gansu, China. NHM (without registration number): 1 fms; Tan-tchang (today’s Dangchang; 34º00ʹN, 104º18ʹE), Gansu. Trechmann Acc. No. 2176. SMF-42045: 4 fms. Dshie-dshou (today’s Wudu, 33°24'N, 104°54'E) China. SMF-42042: 6 fms; Zw. Li-dshia-pu u. Hsi-ku-tsheng (town of Zhouqu County, 33°48'N, 104°18'E), China. SMF-42043: 1 fms. Liang-dshia-pa (unrecognised locality), China. SMF-42041: 4 fms; Tan-tshang, China. SMF-42044: 4 fms; Kuan-ting (today’s Guanting), China. SMF-104052: 2 fms; Tan-tschan; 1885–VI–19.

Distribution. S Gansu (Dangchang, between Lidshiapu and town of Zhouqu, Guanting, Wudu, Lixian).

Diagnosis. Shell with the most swollen part occurred at whorl before penultimate whorl to body whorl. Suture simple. Last whorl straight or gradually ascending towards aperture in front; rounded at periphery. Aperture duplicate; completely attached to body whorl; not armed.

Shell. Turrited; with apex not abruptly pointed; dextral; with the most swollen part occurred at whorl before penultimate whorl; height 10.6–12.1–14.4, diameter major 3.1–3.6–4.1, ratio of height /diameter major 2.58–3.35–4.21. Growth lines usually not very clear. Whorls 8 1/4–9 3/8-–11, convex. Embryonic shell 1 1/2–1 3/4-–2 whorls. Postnuclear whorls smooth. Suture simple. Last whorl mostly gradually ascending or straight in front; rounded at periphery; abaperturally weakly with a rugate region with crowded and/or thickened growthline-like folds. Aperture slightly wavy; ovate, or truncate-ovate; almost vertical; completely attached to body whorl; not armed; height 2.7–3.3–3.7, width 2.1–2.6–3.0, ratio of shell height /apertural height 3.29–3.68–4.44. Duplicate aperture indistinctly present. Reflexed part of peristome straight and not curved backward. Peristome and parietal callus almost completely fusing except for a channel at upper insertion of peristome. Columellar margin reflexed. Columella vertical. Umbilicus narrowly open. Shell white with apex reddish tinted; bandless. Measured specimens: HBUMM-00287, HBUMM- 0 5796, HBUMM- 0 5709, HBUMM- 0 5392, SMF- 42041: 48 shells.

Genitalia. Vas deferens moderately long; evenly thick, or proximally swollen; entering epiphallus with distinct demarcation. Epiphallus moderately long; cylindrical and of uniform thickness; straight or forming a few loops. Epiphallic caecum absent. Flagellum short; conic; proximally normal; with tip blunt. Penis slightly swollen; laterally entering epiphallus; thin-walled. Longitudinal pilasters more than two; not fused at epiphallic pore; forming 1 V-shaped structure. V-shaped pilaster with proximal free end approaching at penial retractor insertion; without papilla formed by fused distal pilasters. Penial process one; sac-like; situated at boundary between epiphallus and penis. Penial appendix short; branched off from proximal portion of penis; with A-1 fused with A-2, and with distinct A-3, A-4 and A-5. A-1 very short. A-2 internally with longitudinal pilasters; near A-3 internally with a ring of papilla. A-3 internally without papilla; 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 distal penis; with appendical branch attaching to A- 1+A-2. Atrium short; with weak atrial retractor. Free oviduct moderately long, or short; longer than vagina, or subequal to vagina in length. Vagina short; not swollen; straight. Bursa copulatrix duct long; proximally twisted. Bursa copulatrix in normal size; well defined; almost sessile; with short neck. Diverticle longer than reservoir; expanded. Bursa copulatrix and diverticle distinguishable; forked more distally from their base. Measurement of genitalia: See Table 2 (HBUMM-05675–specimen 2 and HBUMM-05392–specimen 21 are measured).

Taxonomic remarks. This species is closest to and is easily mixed with Serina ser, especially for some stunt individuals (perhaps with many in a population or a local group), if the identification only depends on shells. However, the two species can be promptly distinguished by the subtle difference in the shape of aperture. In S. ser the aperture is more rounded than that in S. subser .

Figures

FIGURE 1. Distribution of Serina species. S. soluta inflata Yen, 1939 is also indicated although synonymized in this paper. S. soluta stenochila (Möllendorff, 1901) is not mapped due to imprecise locality information.

FIGURE 5. A, B. Serina ser Gredler, 1898. A. SMF- 42036, Wangjiaba. B. ZI RAS N 76. C-E. Serina subser Gredler, 1898. C. NHM- 1902.5.13.23 – 24, Gansu. D. SMF- 42045, Wudu. E. HBUMM- 05392 – specimen 22, Lixian. F-K. Serina soluta (Möllendorff, 1901). F. NHM-Trechmann Acc. No. 2176, Dangchang. G. SMF- 42047, Wasigou. H, I. Serina soluta inflata Yen, 1939. H. HBUMM- 04318 – specimen 2, Luding. I. SMF- 42095, holotype, Kangding. J, K. Buliminus soluta stenochila Möllendorff, 1901. J. SMF- 42048, lectotype, valley of Daduhe River. K. SMF- 42049, paralectotype. L. Serina vincentii (Gredler, 1898), SMF- 42032, between Tshun-dshia-wan and Wangjiaba. M, N. Serina denticulata n. sp. M. HBUMM- 00281 – specimen 5, holotype, Daigusi. N. HBUMM- 00281 – specimen 6, paratype, Daigusi.