A new species of Chondracanthus (Cyclopoida: Chondracanthidae) parasitic on deep-sea Dibranchus spongiosa(Lophiiformes: Ogcocephalidae) from the Eastern Central Pacific.

A total of 228 sampling stations were visited for benthic fauna during a series of oceanographic cruises in the Gulf of California, west coast of the Baja California Peninsula, and Eastern Central Pacific from year 1991 to 2014. Among others, three fish species of the genus Dibranchus were caught in 28 stations. Of these, D. spongiosa was the most common and abundant. Close inspection of this fish revealed the presence of a new species of parasitic copepod, Chondracanthus dibranchi sp. nov., found in the gill cavity of seven specimens of D. spongiosa. Chondracanthus dibranchi sp. nov. seems to be morphologically related to C. psetti and C. janebennettae. The female of C. janebennettae can be separated from these other two congeners by the general shape of the head and abdomen, by the number of teeth on the mandibular blade, and by the general body shape. Chondracanthus psetti and C. dibranchi sp. nov. share the relative lengths of legs 1 and 2, the relative size and shape of the genito-abdomen, and the conical attenuating lateral processes on the trunk of the female. The females of these two species can be separated by the shape and armature of the antennule, shape of the antenna, the claw of the maxilliped, the rami of leg 1 and 2 and posterior processes, the head region, and by the position of the lateral processes of the trunk. An amendment to Tang's (2007) key to the species of Chondracanthus is proposed.