A new species of Enhydrosoma (Copepoda: Harpacticoida: Cletodidae) from Korea, with redescription of E-intermedia and establishment of a new genus

Abstract

Two species of Enhydrosoma Boeck, 1873, found in muddy sediments in the sublittoral zone of Gwangyang Bay, represent the first record of this genus in Korea. Enhydrosoma coreana, new species, shares a number of rare morphological features with the type species, E. curticauda Boeck, 1872, such as a bifid rostrum with centrally inserted sensilla, endopodal lobe of P5 with a peduncle, and a characteristic shape of the female genital field. They differ in the armature formula of the mandible, P1 endopod, and P5 exopod, size of the P5 peduncle, and minor details in the ornamentation of several somites. Enhydrosoma intermedia Chislenko, 1978 is redescribed from its holotype, freshly collected Korean material, and freshly collected material from and near its type locality in the Russian Far East. Its male is described for the first time. Minor morphological differences are observed between these two disjunct populations, such as longer caudal rami and sparse hair-like spinules on somites in Korean specimens. However, molecular data from the mtCOI gene suggest them to be conspecific. Detailed morphological comparisons between E. coreana and E. intermedia reveal a number of important differences, and molecular phylogenies suggest only a remote relationship. Their average pairwise maximum likelihood distances are very similar to those between other well-established genera of harpacticoid copepods. Geehyndrosoma, new genus, is erected to accommodate E. intermedia, together with E. brevipodum Gomez, 2004, from the Pacific coast of Mexico.