A new species of Pseudechinopsyllus George, 2006 (Copepoda, Harpacticoida, Cletodidae) from Campos Basin, Brazil (southwest Atlantic Ocean), with remarks on the phylogeny of the genus

The discovery and description of a new representative of the <i>Ceratonotus</i> group (Copepoda, Harpacticoida, Cletodidae T. Scott) in the Grussaí Canyon off the coast of Brazil opened up the possibility of clarifying the relationship between <i>Echinopsyllus</i> Sars and <i>Pseudechinopsyllus</i> George. <i>Pseudechinopsyllusandrei</i> <b>sp. nov.</b> is characterised by several autapomorphies, including (a) the extensive development of long spinules on the second and third segment of the female antennule, and the strong respectively extreme elongation of (b) the exopod and (c) the setophore on the female P5. Synapomorphies shared with <i>P.sindemarkae</i> include (d) the formation of long spinules at the bases of P2-P4 as well as (e) on exp1 of the P2, and (f) the strong elongation of a tube pore on P2 exp2. Furthermore, the sister group relationship of <i>Pseudechinopsyllus</i> and <i>Echinopsyllus</i> could be substantiated by eleven synapomorphies, among them (g) the large body size, (h) the development of long, rigid cephalothoracic ventrolateral anterior and posterior processes and (i) the loss of the syncoxal seta on the maxilliped. The present study represents a further step towards clarifying the systematic relationships within the <i>Ceratonotus</i> group. A key to the species is provided.