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 Ceratonotus group (Copepoda, Harpacticoida, Cletodidae T. Scott) in the Grussaí Canyon off the coast of Brazil opened up the possibility of clarifying the relationship between Echinopsyllus Sars and Pseudechinopsyllus George. Pseudechinopsyllus andrei sp. nov. 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 P 5.

Synapomorphies shared with P. sindemarkae include (d) the formation of long spinules at the bases of P 2 – P 4 as well as (e) on exp 1 of the P 2, and (f) the strong elongation of a tube pore on P 2 exp 2. Furthermore, the sister group relationship of Pseudechinopsyllus and Echinopsyllus 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 Ceratonotus group. A key to the species is provided.