Laeocathaica dityla Moellendorff, 1899

Figs 2A, 3, 13C-E, 14, 41G, H, 45C, D

Laeocathaica dityla Möllendorff, 1899: 99, pl. 6, fig. 8; - Sturany 1900: 22, pl. 1, figs 4-6; - Wiegmann 1900: 121, pl. 3, figs 108-111; - Gude 1902: 6; - Yen 1939: 150, pl. 15, fig. 42; - Chen and Zhang 2004: 332, fig. 324; - Páll-Gergely et. al.: 57, fig. 16.

Laeocathaica (Laeocathaica) dityla - Zilch 1968: 174; Richardson 1983: 78.

Museum material.

SMF 9086, lectotype. SMF 9087, 1 paratype. SMF 9088, 1 paratype. ZIN RAS No.1, 1 fms.

New material.

HBUMM00532, 2 juvs; Xinglongcun [兴隆村], Zhongzhaixiang [中寨乡], Wenxian, Gansu Province, near point (33.232415°N, 104.419075°E); 1998-V-19, coll. Chen, D.-N. and Zhang, Guo-Qing [张国庆] HBUMM00698, 1 fma and several juvs, 1 fma dissected; Daigusicun [代古寺村], Diebuxian [迭部县], Gansu Province, near point (34.004495°N, 103.940717°E), 1998-V-10, coll. Chen, D.-N. and Zhang, G.-Q. HBUMM05644, 4 fma and several fms; Jiaogongzhen, Wudu, Gansu Province (33.57°N, 104.64°E), broken limestone rocks, 2006-X-02, coll. Liu, J.-M. and Zheng, W. HBUMM05674, 1 fms; eastern bank of Bailongjiang [白龙江], Lianghekou [两河口], Dangchangxian [宕昌县], Gansu Province, near point (33.697332°N, 104.493015°E); limestone; 2006-X-02, coll. Zheng, W. and Gao, L.-H. HBUMM05685, 1 fma and 1 juv; western bank of Bailongjiang, Lianghekou, Dangchangxian, Gansu Province, near point (33.696791°N, 104.49129°E); limestone; 2006-X-02, coll. Zheng, W. and Gao, L.-H. HBUMM05710, 1 fms; Guantingzhen [官亭镇], Dangchangxian, Gansu Province, near point (33.82428°N, 104.538282°E); limestone hills, along 212 Guodao; 2006-X-3, coll. Zheng, W. and Liu, J.-M. HBUMM08449, 3 fms; Shijiba, Wenxian, Gansu Province, near point (33.067582°N, 104.457685°E); 2020-VIII, coll. Chen, Z.-G.

Distribution.

Gansu: Wenxian, Diebuxian, Dangchangxian, Zhouquxian (type locality).

Additional information of shell.

Tiny, low and sparsely arranged granules (~ 10 µm) on the smooth protoconch are present but difficult to be observed because of erosion or weathering. Spiral grooves are absent throughout the shell. On teleoconch the growth lines are not observed except on the part just following the protoconch.

General anatomy.

Eversible head wart present but not prominent. Jaw arcuate, with four or five projecting ribs.

Anatomy of genital organs.

Penial sheath rather short, covering ~ 1/8 of penis. Penis tubular and equally thick. Inside penis, two penial internal pilasters forming one Y-shaped fork at proximal 1/2 of penis, accompanied with another two thicker pilasters. Distal 1/2 of penis occupied by numerous isolated minute diamond-shaped papillae. Vas deferens narrow throughout. Vagina between atrium and dart sac not elongated. Vagina between dart sac and insertion of bursa copulatrix duct approximately as long as dart sac. Dart sac ~ 1/2 length of penis. Love dart ~ 4 mm long, apically 2-bladed and then rounded. Accessory sac small but distinguishable from outside, internally empty but spatially narrow, inserting into dart sac medially, opening to distal dart chamber. Mucous glands two (HBUMM00698-spec.2, spec.3) or three (HBUMM00698-spec.1), each a single tube. Proximal accessory sacs two, dorsally and ventrally touching, without internal pilasters, each with an opening leading to dart chamber near its opening. The right proximal accessory sac somewhat larger and with thicker wall than the left one. Bursa copulatrix duct basally slightly expanded. Bursa copulatrix ovate.

Remarks.

This species has a very unique shell, but the anatomy of the terminal genitalia coincides with those of the congeners.