A new Sphaeronella species (Copepoda: Siphonostomatoida: Nicothoidae) parasitic on Euphilomedes sp. (Ostracoda: Myodocopa: Philomedidae) from Hokkaido, Japan, with an 18S molecular phylogeny.

With about 80 species, Sphaeronella is the most species-rich genus in the copepod family Nicothoidae. To date, 20 named Sphaeronella species have been reported as ectoparasites on ostracod crustaceans. Here we describe Sphaeronella uyenoi sp.

sp. nov. (Crustacea: Ostracoda: Cypridoidea) from Japan, with Information on Its Reproductive Mode.

We describe the cypridoidean ostracod sp. nov. from brackish water on Okinawa Island, Japan.