Bakyietaia guangdungensis ( Kobelt, 1906 ), 2025

Bakyietaia guangdungensis ( Kobelt, 1906) gen. et comb. nov.

Figs 14–15 View Fig View Fig

Vivipara heudei var. guangdungensis Kobelt, 1906 View in CoL in Kobelt 1906 –1909: 124–125, pl. 21 figs 12, 14 (“Provinz Guang-dung”, Guangdong Province, China).

Dactylochalamys guangdungensis – Prashad 1928: 169.

Vivipara polyzonata View in CoL – Yen 1939: 37, pl. 3 figs 14–15 [non Vivipara polyzonata Frauenfeld, 1862 View in CoL ].

Angulyagra guangdungensis – Yen 1943: 128.

Sinotaia polyzonata View in CoL – Zilch 1955: 77, fig. 52. — Qian et al. 2014 [non Vivipara polyzonata Frauenfeld, 1862 View in CoL ].

Taia polyzonata – Johnson 1973: 120, 122. — Palmieri et al. 1980: 40. — Ng 1992: 125. — Chan 1996: 184–185, fig. 2. — Maassen 2001: 44. — Clements et al. 2006: 144. — Tan & Woo 2010: 26. — Yeo & Chia 2010: 32. — Tan et al. 2012: 133 [non Frauenfeld 1862].

Viviparus polyzonata – Ng et al. 1993: 20 [non Vivipara polyzonata Frauenfeld, 1862 View in CoL ].

Bellamya heudei guangdungensis – Shea 1994: 3–11.

Sinotaia guangdungensis View in CoL – Ng et al. 2014: 401–408

Angulyagra polyzonata View in CoL – Madsen & Hung 2014: 110, fig. 2(11) [non Vivipara polyzonata Frauenfeld, 1862 View in CoL ].

Diagnosis

Shell relatively small (20.87 ± 0.93 mm), whorls inflated; 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 28 to 29 small sharp cusps.

Material examined

Lectotype

CHINA • dry preserved spec.; Guangdong Province; O.v. Möllendorff leg.; designated by Yen (1939); SMF.38890 .

Paralectotypes

CHINA • 4 specs (preserved dry); Guangdong Province; O.v. Möllendorff leg.; SMF.38822 .

Other material

CHINA – Guangdong Province • 1 spec. (preserved dry); Guangzhou City, Baiyun Mountain , creeks in Taohuajian Valley , mud substrate, on bank; 25 Feb. 2022; Le-Jia Zhang leg.; KIZ.240054 • 1 spec. (preserved in ethanol); Qingyuan City, Lianzhou County, Xian Town ; 18 Nov. 2019; bought by Hai-Ling Zhang on local market; ZMB.122693-1 • 3 specs (preserved in ethanol); Zhaoqing City, Bohai Park , Qixing Lake , 0.1–0.2 m deep under rocks; 19 Jan. 2020; Ji-Lin Jiang leg.; ZMB.122760 . – Guangxi • 4 specs (preserved in ethanol); Guilin City, Yangshuo Town ; 14 Mar. 2022; bought on local market by Le-Jia Zhang; ZMB.122727 • 2 specs (preserved in ethanol); Laibin City, Heshan County, Renyi Village , Huaiji Reservoir , 0.5 m deep mud substrate; 7 Jan. 2020; Ri-Bao Huang leg.; KIZ.240088 .

SINGAPORE • 3 specs (preserved in ethanol); Canal at Springleaf Rd ; ZMB.192077 .

Description

Adult shell ( Fig. 14A–H, K–R View Fig ) relatively small for the genus (20.87 ± 0.93 mm), thin but sturdy, conical, olive to olive brown, with five to six whorls, apex acute; teleoconch whorls inflated, sometimes with shoulder, 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 three to five 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, adult columellar lip recurved, sometimes forming a relatively narrow crescent-shaped callus, this structure or columellar lip completely covering umbilicus.

Operculum ( Fig. 14I–J View Fig ) corneous, ovate, relatively thin, yellow to orange; 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. 15 View Fig ) (n = 3) 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 of lateral tooth in width, with one broad central denticle and three to four small sharp cusps on either side; outer marginal tooth wide, almost same width as lateral tooth, with 28 to 30 small sharp cusps.

Remarks

The newly collected specimens from Guangzhou City of Guangdong have a shell that is very similar to that of the lectotype. Bakyietaia guangdungensis can be distinguished from most congeners based on its relatively small conical shell with inflated whorls, but largely falls within the range of variation of Bakyietaia wilhelmi . However, B. guangdungensis has a greater number of small cusps on the outer marginal teeth than B. wilhelmi (28–29 vs 18–25). Both of these species also overlap in geographic range, and, therefore, DNA barcoding is recommended for the unambiguous identification of these two species. The recommended Chinese name is 广东ṉ田ª.

Habitat and distribution

Mud and rock substrate in the shallow water of rivers and lakes in Western Guangdong and Eastern Guangxi, China. Introduced into Singapore and Sydney, Australia, possibly also in Malaysia (pending confirmation using molecular evidence).