Description of Barathricola thermophilus, a new species from a deep-sea hydrothermal vent field in the Indian Ocean with redescription of the Barothricola type species (Crustacea, Copepoda, Cyclopoida)

Abstract

Re-study of the type species of the genus Barathricola Humes, 1999 (Copepoda, Cyclopoida, Schminkepinellidae) described from the Pacific Ocean (Juan de Fuca Ridge), and study of the species Barathricola thermophilus sp. nov. from a deep-sea hydrothermal vent field on the Central Ridge in the Indian Ocean revealed a derived feature and widespread geographic distribution of this deep-sea genus of cyclopoids. The derived feature of Barathrieola is the sexually dimorphic third endopodal segment of leg 3 possessing a small outer terminal spine together with spine-like outgrowths on this segment. The new species differs from Barathricola rimensis Humes, 1999 in not expressing sexual dimorphism in leg 5, having three spines and one seta on its exopod in both sexes (B. rimensis has three spines and one seta on the female exopod but three spines and two setae on the male exopod) and in having broader caudal rami which are 8.9 times longer than wide in the female (this ratio for B. rimensis is 11). An amended diagnosis of the genus Barathricola, a key and a table of morphological differences for all species of Schminkepinellidae are given.