Ademoixys gen. nov.

Diagnosis. Body linear, fusiform. Cephalosome clearly defined. First and second pedigerous somite indistinctly defined; fused third and fourth pedigerous somites oval. Freeurosome indistinctly 4-segmented. Caudalramus armed with 6 small setae. Rostrum as small anteroventral lobe on frontal margin of dorsal cephalic shield. Antennule small, unsegmented. Antenna 3-segmented with small terminal claw. Mandible consisting of coxa extending medially as large hook, and palp consistingof basis and 1-segmented rami, armed with 1 seta on basis, 4 onexopodand 5 on endopod. Maxillule simplified, represented by lobe bearing several setae. Maxilla 4- segmentedwith 2-segmented endopod; lacking defined claw on basis. Maxilliped as lobe bearing setae distally. Legs 1–4 biramous, each with 2-segmented protopod. All swimming legs unarmed, except inner distal spine on basis of leg 1. Legs 2–4 with 3-segmented exopods and 2-segmented endopods. Leg 5 represented by tapering posteroventral process on somite.

Typeandonly species. Ademoixysfusiforma (Ooishi, 1972) comb. nov. (originally as Demoixys fusiforma), by original designation

Etymology. From “ a ” (Greek prefix meaning “not”) and the generic name Demoixys, referring to the differences between the new genus and Demoixys. Gender feminine.

Remarks. Ooishi (1972) described D. fusiforma based on material found living in association with the ascidian Distaplia dubia (Oka, 1927) in Japanese waters. This copepod differs fundamentally from known species of Demoixys, so the new genus, Ademoixys gen. nov., is established to accommodate it as type species. The significant features defining the new genus are the transformation of the coxal gnathobase of the mandible into a powerful hook, the fusiform body, and the distinct butunarmed rami of the swimming legs.