Dalipaludina occidentalis (Annandale, 1924) Zhang & Du & von Rintelen, 2023

Zhang, Le-Jia, Du, Li-Na & von Rintelen, Thomas, 2023, A new genus of river snails, Dalipaludina (Gastropoda, Viviparidae), endemic to the Yunnan Plateau of SW China, Zoosystematics and Evolution 99 (2), pp. 285-297 : 285

Dalipaludina occidentalis (Annandale, 1924) comb. nov.

Lecythoconcha malleata f. occidentalis Annandale, 1924: 415 ("Ho-ching and Shihku", Heqing County and Shigu town, Lijiang City, Yunnan, China).

Viviparus occidentalis - Yen 1942.

Material examined.

8 specimens in ZMB, collected by local fishermen from 3 to 5 metres depth in the south shore of Lake Jianhu. February 2020 ; 4 specimens in ZMB, collected by Le-Jia Zhang from 0.5 metres depth in an unnamed pond on the Sheshan hill in Lijiang City in April 2022; 19 specimens in NJW, collected by Jiao-Wei Ning from Lake Jianhu .

Description.

Shell (Fig. 5A-G ) large, broadly conical or sub globose, thin, olive to dark brown in colour; up to six whorls at adulthood, including one relatively smooth protoconch whorl, apex acute; teleoconch whorls inflated, occasionally shouldered, with one strong keel at suture, above suture with many weak spiral threads, sometimes with additional two to three stronger cords, base of shell with many thin weak spiral threads, weak spiral threads and cords with short periostracum setae; aperture ovate, slightly less than half of shell in height, lip thin and simple, umbilicus narrow, sometimes bordered by akeel.

Operculum (Fig. 5H ) corneous, ovate, rather thin, yellow, with red nuclear region, exterior surface of operculum rather smooth, inner opercular region relatively small, nuclear region smooth.

Radular (Fig. 7E, F ) central tooth with one broad central denticle and four small sharp cusps on either side; lateral tooth with one broad central denticle and four small sharp cusps on either side; inner marginal tooth with one broad central denticle and four small sharp cusps on either side; outer marginal tooth with 9 to 10 small sharp cusps.

Remarks.

This species differs from the other species of Dalipaludina by having rather inflated, shouldered whorls. Annandale (1924) presented a photo of the type specimen. The shell morphology and COI phylogeny of the specimens collected from an unnamed pond in Lijiang City, which is very close to the type locality, confirm that this species should be assigned to Dalipaludina . The recommended Chinese name of this species is “滇西理田螺”.

Habitat and distribution.

Shallow ponds with muddy bottoms and abundant aquatic plants in Lijiang City, Yunnan, China; Shallow to medium-depth water area with muddy bottoms in Lake Jianhu, Jianchuan County, Yunnan, China.

Figures

Figure 5. Shell and operculum of Dalipaludina occidentalis. A-C. Specimen collected from Lake Jianhu, ZMB. Moll. 122712; D, E. Varieties collected from Lake Jianhu, ZMB. Moll. 122713; F. Sub-adult collected from Lake Jianhu, ZMB. Moll. 122713; G. Original figure of the type specimen in Annandale, 1922; H. Exterior (left) and interior (right) surface of operculum. Scale bar: 1 cm, B-F with the same scale bar of A.

Figure 7. SEM photo of the radula and the protoconch of Dalipaludina species. A, B. Radula of Dalipaludina delavayana, A- ZMB. Moll. 181719, B- ZMB. Moll. 122707; C, D. Radula of Dalipaludina oxytropoides, ZMB. Moll. 250844; E, F. Radula of Dalipaludina occidentalis, ZMB. Moll. 122713. Abbreviations: ct-central teeth; lt-lateral teeth; imt-inner marginal teeth; omt-outer marginal teeth. Scale bars: 100 µm.