Bakyietaia duchieri ( Fischer, 1898 ), 2025

Bakyietaia duchieri ( Fischer, 1898) gen. et comb. nov.

Fig. 13 View Fig

Paludina duchieri Fischer, 1898: 330–331 View in CoL , pl. 18 figs 48–49 (“Riv. Song-KI-Kong, à Déo-Cat”, Kỳ Cùng River, at Đèo Khách, Lạng SƠn, Vietnam).

Angulyagra duchieri View in CoL – Starobogatov 1970: 202. — Thanh et al. 2004: 3–4, fig. 5.

Angulyagra boettgeri View in CoL – Madsen & Hung 2014: 109, figs 2 (10 left), (10 middle) [non Paludina duchieri Fischer, 1898 View in CoL ].

Diagnosis

Shell large (32.88 ± 1.00 mm), thick and sturdy, whorls inflated, with narrow angular shoulder; columellar lip recurved, forming callus covering umbilicus completely; operculum with small nuclear region (around 1/5 of inner opercular region) with shiny grains or veins.

Material examined

Holotype

VIETNAM • dry preserved spec.; Lạng SƠn, Đèo Khách, Kỳ Cùng River ; Juillet Billet leg.; MNHN-IM-2000-4486 .

Other material

CHINA • 2 specs (preserved in ethanol); Guangxi, Chongzuo City, Longzhou County, Shuikou Town , Poliu Village , Shuikou River , 0.5 m deep on mud substrate; 4 Mar. 2023; KIZ.240049 , KIZ.240050 .

VIETNAM • 1 spec. (preserved dry); “Tonkin” ( Hanoi); O.v. Möllendorff leg.; SMF.48146

Description

Adult shell ( Fig. 13A–K View Fig ) large (32.88 ± 1.00 mm), thick, sturdy, conical, olive to olive brown, with six whorls, apex acute; teleoconch whorls slightly inflated, with three smooth primary keels, with one to two weaker smooth secondary keels located between suture and first keel, sometimes one additional weak keel located between first and second/second and third keels, base of shell with one to three weak keels, all keels usually darker than rest of shell surface; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with an obvious angular periphery, columellar lip covered with thick inner shell layers, white or orange red, adult columellar lip recurved, sometimes forming a narrow to wide crescent-shaped callus, this structure or columellar lip completely covering umbilicus.

Operculum ( Fig. 13M–N View Fig ) corneous, ovate, relatively thick, dark red; exterior surface smooth; interior surface with small nuclear region, around 1/5 of inner opercular region, with shiny grains or veins or smooth glossy surface.

Radula currently unknown.

Remarks

The newly collected specimens in Longzhou of China have a shell that is very similar to that of the holotype, and the collecting site is close to the type locality on the same river basin. Bakyietaia duchieri can be easily distinguished from the other species of Bakyietaia gen. nov. based on its large sturdy shell and inflated body whorl with shoulder. The recommended Chinese name is IJ氏ṉ田ª.

Habitat and distribution

Sand substrate and rocks in the shallow water of rivers and lakes of Western Guangxi, China and Northern Vietnam.