Xingyuan Xiang, He, Li & Chen, 2025

Genus Xingyuan Xiang, He, Li & Chen View in CoL , gen. nov.

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Type species. Xingyuan jiamingzhangi gen. et sp. nov.

Diagnosis. Shell patelliform; apex prominent, blunt, curves downwards to the right and rolled, surpassing the right edge of shell; a boundary between protoconch and teleoconch.

Differential diagnosis. In terms of shell morphology, Xingyuan gen. nov. has an apex that is prominent, curves downwards to the right, and is rolled, surpassing the right edge of the shell. This distinguishes it from all other species in the subfamily. Comparatively, only species of Ancylastrum Bourguignat, 1853 and Erinna Adams & Adams, 1855 show some similarity. The apex of Xingyuan gen. nov. is rolled in a manner (similar to Gyraulus Charpentier, 1837 ), with the roll extending over 1.5 whorls. In contrast, species of Ancylastrum either have an apex rolled by less than one whorl or a more inwardly curled rolling pattern. The protoconch of Xingyuan gen. nov. is positioned at the upper end of the teleoconch horizontally, while in Ancylastrum species, the protoconch is located lower than or at the same level as the height of the teleoconch. Athough the genus Erinna have a shell morphology that is relatively similar, it is noting that Erinna is currently endemic to Hawaiian Islands and it is not likely related to the Yunnan genus.

Etymology. The genus name " Xingyuan " is derived from the Chinese idiom "xing huo liao yuan," which is often used to describe a new phenomenon that, although initially small in strength, possesses strong vitality. This suggests the robust vitality of the species in this family. We suggest the Chinese common name as " wāDz ".

Distribution and ecology. The species of this genus have currently been found only in Lake Fuxian, located in Yuxi City, Yunnan Province, China. They have been discovered exclusively in strata containing Rhombuniopsis linan , with no shells found in more recent strata, nor have any living individuals been observed in the lake.