Pincerna costulosa (Bavay & Dautzenberg, 1912)

Alycaeus costulosus Bavay & Dautzenberg, 1912: 49-50, pl. 4, figs 1-4.

Pincerna costulosa - Z.-Y. Chen & M. Wu 2020: 45, figs 1, 4C, D

Type locality.

"Phong-Tho, Tonkin".

Material examined.

Tonkin, Phong Tho, leg. Messager, MNHN-IM-2000-31786 (1 syntype); Tonkin, Phong Tho, probably leg. Messager, coll. Staadt, 1969, MNHN-2012-27043 (4 shells, 2 of them typical costulosus , 2 other shells small vanbuensis ).

Remarks.

Protoconch matte, no spiral lines visible; R1 strongly, regularly ribbed with hardly visible, extremely fine spiral striation; R2 extremely short, with ca. seven narrow, light stripes, the overall surface is smooth.

Some Indian species originally included in Cycloryx (e.g., P. graphica var. dihingensis , P. thompsoni , P. burrailensis ) are so similar to P. costulosa that it was challenging to find any notable differences. Pincerna costulosa must evidently be classified in Pincerna in the face of the large geographic gap between it and the Indian/Burmese species.