A new species and a newly recorded species of the genus Hua (Gastropoda: Semisulcospiridae) from the Chishui River, Yunnan, China

A new species of Hua, Hua chishuiensis sp. nov., is described from the upper Yangtze River Basin in Yunnan Province, China, based on morphological and molecular evidence. The new species is distinguished from its congeners by a combination of characters, including a smooth shell with 4–6 whorls, central teeth with a triangular pointed major cusp and 3–4 smaller cusps on each side, inner marginal teeth with five denticles and outer marginal teeth with eight flattened denticles, a body width of about 57.1–71.8% of shell height and a large body whorl comprising about 77.8–88.0% of shell height. Molecular analysis based on partial mitochondrial COI and 16S rDNA also supports the systematic position of the new taxon. Furthermore, the article documents the first record of Hua wujiangensis in the Chishui River, where its shell morphology deviates markedly from the type material, a pattern likely reflecting phenotypic responses to the localised environmental conditions prevailing in these isolated habitats. These findings expand our understanding of freshwater molluscan diversity in southwestern China and underscore the karst landscapes as a pivotal centre of endemism and cryptic diversity for freshwater gastropods.