A New Genus of Ectinosomatidae (Copepoda, Harpacticoida) Symbiont in the Digestive Tract of <i>Eudistoma vannamei</i> Millar, 1977 (<i>Ascidia</i>, <i>Polycitoridae</i>)

Abstract

A new genus of Ectinosomatidae is recorded in association with an Ascidia from a permanent submerged coral community in Barra Beach, Salvador City, Bahia State (Brazil). The new taxon belongs to a smaller group of genera in the family Ectinosomatidae based on the geniculate maxilla and the prehensile first swimming leg. This group is composed of Bradiellopsis, Chaulionyx, Halophytophilus, and Sigmatidium. The new genus differs from the others due to distinct aspects of the mandible gnathobasis, which features sharp processes on the pars incisiva and pars molaris followed by a short spinulated area and a serrulated seta; the presence of a two-segmented endopod of the first swimming leg, with the first endopodal segment longer than all exopodites combined; and a short, quadratic second endopodal segment with two strong curved claws. In addition, it differs from other genera due to the distinct armature of the first to fourth swimming legs and the presence of fused exopod and baseoendopod on the fifth swimming leg. Cruscollatus gen.nov. lives specifically within the digestive tract of Eudistoma vannamei Millar, 1977, an Ascidia species endemic to northeastern Brazil. This study reports the first documented association between a harpacticoid copepod of the family Ectinosomatidae (order Harpacticoida) and ascidian hosts (Ascidia).

Keywords

• associated fauna
• new species
• symbiotic copepod
• taxonomy