Plectotropis yonganensis, Zhou, Wei-Chuan, Xiao, Qiong, Chen, De-Niu & Hwang, Chung-Chi, 2011

Zhou, Wei-Chuan, Xiao, Qiong, Chen, De-Niu & Hwang, Chung-Chi, 2011, Plectotropis yonganensis sp. nov. (Gastropoda: Bradybaenidae) from China, with revision of two Chinese camaenid species (Gastropoda: Camaenidae), Zootaxa 2929, pp. 51-56 : 54-55

Plectotropis yonganensis sp. nov.

( Fig. 1 , J–M; Fig. 2 , C)

Holotype. (FJIQBC 181201) Shell height 10.8 mm, shell width 14.2 mm, aperture height 6.6 mm, aperture width 6.7 mm, June 2, 2007, collected from the type locality.

Paratype. (FJIQBC 181202 – 181219) 18 specimens, one of them is young snail. Shell height 9.4–11.6 mm, shell width 12.9–14.3 mm, aperture height 5.2–6.5 mm, aperture width 6.1–7.1 mm, June 2, 2007, collected from the type locality.

Type locality. Stone Forest in Yongan, Fujian (26°3ʹ31.50ʺN, 117°19ʹ44.24ʺE).

Etymology. The name of the new species refers type locality.

Shell. Sized medium, thin, transparent but solid, high-conical. Whorls 7 1/2, growing uniformly, slowly, slight convex above, base flat. Spire high. Periphery acutely keeled, decorated with rough, short, spaced ridges immediately around keel in most specimens. Peripherical hair present, short, triangular, ease to worn off when matured. Color of shell milk-white, without color band or spot. Growth lines delicate, dense, oblique, slightly curved, staggered with dense, weak spiral lines. Aperture semicircle or near rectangular. Peristome thin, a little expanded; columellar lip short, vertical, reflected, barely covering umbilicus; basal lip almost straight towards periphery; inner lip covered by thin callus. Umbilicus deep, small, 1.5 mm in diameter; ratio of umbilicus width to shell width 0.07–0.10.

Reproductive system. Penis long and thick. Epiphallus short, about 1/7 length of penis. Flagellum thick, fusiform, with a pointed tip, about 1.5 times length of epiphallus. Vas deferens slender. Oviduct thick and long. Vagina long and thin, expanded at base. Pedunculus of bursa copulatrix thick at basal 2/3, thin close to bursa copulatrix. Bursa copulatrix nearly round. Dart sac close to atrium, oval, with expanded top. Accessory sac sized half of dart sac. Mucus glands inserting laterally at accessory sac, six branches, long, about 2.5 times of dart sack, with some branches diverged. Habitat. The type locality is a hill of Karst landform. We did not found this new species in the farm or hills nearby the site. The snail usually lives in bushes, tussocks, under stone, forest litter and stone gaps, or limestone of moist and humus.

Remark. The new species is very similar to P. brevibarbis in having high-conical and white shell. The two species can be distinguished by the following four differences: 1. the size of shell P. brevibarbis is larger than the new species; 2. the reproductive system of the new species has 3 pairs of mucus glands while P. brevibarbis has only 1 pair; 3. the new species has more vertical columellar lip and more straight basal lip than P. brevibarbis ; 4. the umbilicus of the new species (umbilicus diameter / shell width = 0.07–0.10) is smaller than P. brevibarbis (umbilicus diameter / shell width = 0.12–0.16). Besides, all the examined specimens do not have a color band surrounding the periphery, as seen in P. brevibarbis .

Figures

FIGURE 1. Map of sampling sites and photographs of shells. A, Sampling sites of Fujian and Zhejiang, China. Square—type locality for Plectotropis yonganensis sp. nov.; Circles—sites with Satsuma stenozona; Triangles—sites with Plectotropis brevibarbis; B – E, Photographs of Satsuma stenozona from the National Forest Park of Fuzhou, China. B, C, D, (FJIQBC 18220), E (FJIQBC 18237); F – I, Photographs of Plectotropis brevibarbis. F, H, I, (FJIQBC 18256) from Tianmu Mountain, Zhejiang, China. G, (FJIQBC 18271) from Sanmen of Zhejiang, China, showing peripherical hairs; J – M, Photographs of Plectotropis yonganensis sp. nov. from Stone Forest, Yongan, Fujian China. J, L, M (FJIQBC 181201) holotype, K, (FJIQBC 181205) paratype, showing peripherical hairs.

FIGURE 2. Reproductive system. A, Satsuma stenozona from Drum Mountain, Fuzhou, China (FJIQBC 18245); B, Plectotropis brevibarbis from Tianmu Mountain, Zhejiang, China (FJIQBC 18226); C. Plectotropis yonganensis sp. nov. from Stone Forest, Yongan, Fujian China (FJIQBC 181219). AG: albumen gland; E: epiphallus; F: flagellum; HD: hermaphroditic duct; P: penis; PR: penis retractor muscle; BC: bursa copulatrix; PBC: pedunculus of bursa copulatrix; VD: vas deferens; S: stylophore or dart sac; AS: accessory sac; MG: mucus glands.