Dalipaludina delavayana (Heude, 1889) 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 delavayana (Heude, 1889) comb. nov.

Paludina delavayana Heude, 1889: 47 ("lacu Ta-li fou", Lake Erhai).

Sinotaia delavayana - Qian et al. 2014.

Material examined.

2 syntypes, IZCAS-FG-492553, IZCAS-FG-492554; 1 paratype, MCZ-Mala-167342; 8 specimens in ZMB, collected by Le-Jia Zhang from around 0.5 to 1 metres depth in the north shore of Lake Cibi in Augest 2018 , 2 specimens in ZMB, collected by Jiao-Wei Ning from around 1 to 2 metres depth in Lake Haixihai ; 17 specimens in NJW, collected by Jiao-Wei Ning from around 1 to 2 metres depth in Lake Cibi .

Description.

Shell (Fig. 3A-H ) large, conical, thin, greenish yellow to dark olive in colour; up to six whorls at adulthood, including one relatively smooth protoconch whorl, apex acute, spire high; each teleoconch whorls with one strong keel at suture, above suture smooth or with many weak spiral threads, sometimes with additional two to three stronger cords, base of shell with many thin weak spiral threads, weak spiral cords and threads with short periostracal hairs; aperture ovate, less than half of shell in height, lip thin and simple, umbilicus narrow, sometimes bordered by a keel.

Operculum (Fig. 3I ) corneous, ovate, rather thin, yellow, with reddish brown nuclear region, exterior surface of operculum rather smooth, inner opercular region relatively small, nuclear region smooth.

Radular (Fig. 7A, B ) central tooth with one broad central denticle and with 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 three small sharp cusps on either side; outer marginal tooth with 10 to 11 small sharp cusps.

Remarks.

This species differs from the other Dalipaludina species by having a larger shell with a higher spiral. It may be difficult to distinguish from the smooth form of Dalipaludina oxytropoides from Lake Lugu based on morphology. However, this species is not recorded from Lake Lugu, and can be distinguished from D. oxytropoides based on differences in COI gene sequences. The recommended Chinese name of this species is “德拉维理田螺”.

Habitat and distribution.

shallow water area with sandy and muddy bottoms in Erhai, Cibi and Haixihai, Yunnan, China.

Figures

Figure 3. Shell and operculum of Dalipaludina delavayana. A-C. Specimen collected from Lake Cibi, ZMB Moll. 122707; D, E. Varieties collected from Lake Cibi, ZMB Moll. 122707; F. specimen collected from Lake Haixihai, LJZ; G. Paratype MCZ-Mala- 167342, photo taken by Alana Rivera, Museum of Comparative Zoology, Harvard University, President and Fellows of Harvard College; H. Syntype IZCAS-FG- 492554, photo taken by Kaibaryer Meng, Institute of Zoology, Chinese Academy of Sciences; I. Exterior (left) and interior (right) surface of operculum. Scale bar: 1 cm, B-H 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.