A new genus and species of the family Mantridae (Copepoda: Cyclopoida) infesting the bivalve Pseudochama retroversa from the Seto Inland Sea,western Japan

Chamicola nagasawai n. gen., n. sp., belonging to the bivalve-infesting cyclopoid family Mantridae, is described from the Seto Inland Sea, western Japan. This is the first recorded occurrence in the Pacific Ocean of the family, which previously accommodated only two genera, Mantra and Nearchinotodelphys. The parasite was found in the mantle cavity of Pseudochama retroversa (Lischke) (Family Chamidae), but did not infect Chama japonica (Lamarck). The prevalence and intensity of C. nagasawai in P. retroversa ranged from 11.3 to 25.0%, and from 1.0 to 2.6, respectively. Considering the host affinity and distribution of ancestral and derived character states, the new genus seems to be more closely related to Mantra than to Nearchinotodelphys.