Catiniid copepods are characterized by the presence of a pedunculate sucker on the antenna. Four genera are currently included in the family Catiniidae: Catinia, Cotylemyzon, Cotylomolgus and Myzomolgus, the most speciose. Within the framework of the Special Research Program "Conservation and Sustainable Use of the Biodiversity of the State of São Paulo - Biota/FAPESP", a new species of Myzomolgus was found as an external associate of Sipunculus nudus and S. phalloides phalloides. The sipunculan worms were collected during the low tide in Araçá Beach, State of São Paulo, Brazil (23º49’02"S, 45º24’19"W). The new species differs from its three congeners, namely M. stupendus from France and M. tenuis and M. orientalis from Korea, by the peculiar ornamentation of the third antennal segment, morphology of mandible and leg 6 and presence of denticulate area between maxillipeds. The description of this new species raises to four the number of catiniid species (one of Catinia and two of Myzomolgus) associated with the widely distributed S. nudus. In Brazil, this is the first record of Myzomolgus and the second species associated with sipunculan worms (a new species of Catinia found on S. phalloides phalloides is under description).
Marine parasite; Sipunculus; taxonomy
