Caridina zhaoi sp. nov., a new stygobiont atyid shrimp (Decapoda, Caridea, Atyidae) from a limestone cave in Guizhou Province, China

A new stygobiont species of freshwater shrimp, Caridina zhaoi sp. nov ., from a karst cave in Guiyang, Guizhou Province, southwestern China, is described and illustrated. The new species is morphologically distinct from its epigean congeners by a suite of stygobiotic characters, including the degeneration of eyes and absence of body pigmentation. It can be further distinguished from other known Chinese cavernicolous Caridina species by the combination of a relatively long rostrum with a specific rostral formula, the length of the stylocerite, the proportions of various joints of the first and second pereiopods, and the armature of the dactylus of the third and fifth pereiopods. Molecular analysis based on the mitochondrial COI gene reveals a high genetic divergence (14.70%–23.47%) between the new species and other atyids, supporting its validity as a distinct species. This discovery brings the total number of stygobiont Caridina species in China to 10, highlighting the rich but underestimated subterranean biodiversity of the Guizhou karst region.