Integrative taxonomy reveals the Caridina clinata Cai, Nguyen & Ng, 1999 species complex (Crustacea, Decapoda, Atyidae), with descriptions of eight new species from Hainan Island, China

Integrative analyses revealed that Caridina clinata Cai, Nguyen & Ng, 1999 represents a species complex comprising nine sibling species distributed across Hainan Island (China) and Vietnam. Among these, C. clinata sensu stricto (the nominal species itself) occurs in both regions, C. haivanensis is endemic to Vietnam, and the seven newly described species are endemic to Hainan Island. Evidence showed that the C. clinata population reported by Cai (2014) from Wuzhishan was actually a new species, herein described as C. caii sp. nov. This study documents nine Caridina species from Hainan Island, including eight new species and one newly recorded species. The new species are: C. wenchangensis sp. nov. , C. qiongzhongensis sp. nov. , C. huangi sp. nov. , C. hepingensis sp. nov. , C. fontinalis sp. nov. , C. tunchengensis sp. nov. , C. brevilineata sp. nov. , and C. caii sp. nov. Additionally, Caridina clinata is recorded for the first time from Ledong, Hainan, and is redescribed herein. For each species, we provide comprehensive morphological descriptions, illustrations, taxonomic notes, habitat parameters, and IUCN threat assessments. Furthermore, we clarify the phylogenetic relationships between the newly discovered species and their congeners.