Bakyietaia fontinalis Zhang, Yen & von Rintelen, 2025

Bakyietaia fontinalis Zhang, Yen & von Rintelen gen. et sp. nov.

urn:lsid:zoobank.org:act:

Figs 32–33 View Fig View Fig

Diagnosis

Shell medium in size (24.25 ± 2.59 mm), sturdy, conical, whorls not inflated, with weak primary keels, shoulder rounded; 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; outer marginal tooth of radula with 26–29 small sharp cusps.

Etymology

Refers to the cold spring habitat of the type locality. The recommended Chinese name is ṅẹṉ田ª.

Material examined

Holotype

CHINA • spec. preserved in ethanol; Hainan Province, Dingan County, Jiuwentang Town, Jiuwentang Cold Spring , 0.5 m deep on mud and sand substrate; 6 Mar. 2022; Le-Jia Zhang leg.; KIZ.240042 . Paratypes

CHINA • 1 spec. (preserved in ethanol); same data as for holotype; KIZ.240043 • 2 specs (preserved in ethanol); same data as for holotype; ZMB.122733 • 1 spec. (preserved in ethanol); same data as for holotype; KIZ.240102 • 2 specs (preserved in ethanol); Hainan Province, Dingan County, river near Leiming Town; 2018; KIZ.240103 • 1 spec. (preserved in ethanol); Hainan Province, Qionghai City, Shibi Town , Wanquan River , 0.1 m deep on rock; 7 Mar. 2022; Le-Jia Zhang leg., KIZ.240104 .

Other material

CHINA • 1 spec. (preserved dry); same data as for holotype; YHY-BAKFON-LQ-1 .

Description

Adult shell ( Fig. 32A–G View Fig ) medium in size (24.25 ± 2.59 mm), thin to thick, sturdy, conical, olive to dark olive brown, with five whorls, apex acute; teleoconch whorls not inflated, with three weak but obvious smooth primary keels, with one to two weaker smooth secondary keel located between suture and first keel, always with one additional weak keel located between first and second/second and third keels, base of shell with two to four weak keels, all keels usually darker than the other part of shell surface in colour; aperture ovate, less than half of shell in height, inner shell surface bluish white, outer lip thin, always with a strong angular periphery, columellar lip covered with thick inner shell layers, white or orange, adult columellar lip recurved, sometimes forming a crescent-shaped callus, this structure or columellar lip completely covering umbilicus.

Operculum ( Fig. 32H–I View Fig ) corneous, ovate, thin, orange to 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.

Radular ( Fig. 33 View Fig ) (n = 2) central tooth with one broad central denticle and four to five small sharp cusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth narrow, about half width of lateral tooth, with one broad central denticle and four to five small sharp cusps on either side; outer marginal tooth wide, almost same as lateral tooth in width, with 26 to 29 small sharp cusps.

Remarks

Bakyietaia fontinalis gen. et sp. nov. is one of the species of Bakyietaia gen. nov. with weak primary keels. This species can be easily distinguished from all congeners, especially the morphologically similar species B. mutica , based on its medium-sized conical shell with whorls not inflated, rounded shoulder and more cusps on the outer marginal teeth (26–29 vs 19–24).

Habitat and distribution

Mud and rock substrate in the shallow water of springs and rivers of central-eastern Hainan Province, China.