Thaicypridopsis baimaii sp. nov. (Crustacea: Ostracoda) from Western Thailand, with Discussion on Distribution and Ecology of the Genus

Thaicypridopsis is rare and endemic to Thailand, appearing as a monospecific genus since its discovery. The recent investigation of ostracods in northeast Thailand, together with the reexamination of collections from other parts, including the poorly surveyed western region, uncovers the second and new species of this genus, T. baimaii sp. nov. The unveiling not only allows reconsideration of generic and specific characters within the genus but also fills a gap in the ostracod diversity of Thailand. Thaicypridopsis baimaii sp. nov. described from freshwater in the west, primarily differs from T. longispinosa Savatenalinton, 2018 by the short and smooth spines on the valve surface, the protruded posterior extremity of the right valve, the β seta on the mandibular palp with a remarkably long flagellum-like tip, and the number of large modified bristles on the first and the second endites of the maxillula. The detailed examination of the valve surface in the present work sheds light on the affinity among the Cypridopsinae genera. This study also updates the localities and distribution map of T. longispinosa and reveals the different geographic dispersal of these two species. The frequency of occurrence, with a large number of sampled localities in the northeast in particular, allows further discussion on allopatric evolution and ecology of the genus. A key to the genera of the tribe Zonocypridini is provided.