A New Species of the Genus Sarscypridopsis (Crustacea: Ostracoda) Discovered in a Japanese Rice Field

Sampling of rice fields in Kanagawa Prefecture, Japan, yielded an undescribed species of the non-marine ostracod genus Sarscypridopsis McKenzie, 1977. Small marginal denticles on the left valve give this species its name: Sarscypridopsis denticulata n. sp. Most species of the genus Sarscypridopsis are restricted to Africa, and based on morphological characters, the closest congener of this new species is native to Botswana. We therefore conclude that this species is probably not native to Japan, and it joins six other non-marine ostracod species that are probably or possibly alien or invasive in Japan. Including the new species, four of these are associated with rice fields. All specimens of Sarscypridopsis denticulata n. sp. are female, and one of the antennal claws (claw G2) is more robust and with better developed serration compared with the other antennal claws. This is a feature of several Cypridopsinae lineages, but in females only. An overview of the zoogeographical distribution of the genus is provided.