Two new species of Colobomatus Hesse, 1873 (Crustacea: Philichthyidae) parasitic in the interorbital canals of Holocentrus spp. (Holocentriformes: Holocentridae) in the South Atlantic Ocean.

Two new species of parasitic copepods of the genus Colobomatus Hesse, 1873 (Cyclopoida) are proposed based on specimens collected from the squirrelfishes (Holocentridae) off the coast of Rio de Janeiro, Brazil. Colobomatus luquei n. sp. from the interorbital canals of Holocentrus adscensionis (Osbeck) can be distinguished from its closest congeners by the following combination of characters in the adult female: first to fourth thoracic somites fused, two pairs of thoracic processes, fifth pedigerous somite without processes, and process in the third abdominal somite not transpassing the margins of the caudal rami; and in the adult male: antenna with two elements in the second endopodal segment, leg 1 with three spines and three setae in the second endopodal segment, and leg 2 with three spines and three setae in the second exopodal segment. Colobomatus freirei n. sp. from the interorbital canals of Holocentrus rufus (Walbaum) can be distinguished from its closest congeners through the possession of an anterior pair of thoracic processes four times longer than the posterior pair. The two new species described herein are the first representatives of the family Philichthyidae found to parasitize fish of the order Holocentriformes.