RESUMEN
The present study provides new host and first description of the male of Colobomatus stelliferi Pombo, Turra, Paschoal & Luque, 2015 (Copepoda, Philichthyidae), collected from the mandibular canals of the Argentine croaker Umbrina canosai Berg, off the State of Rio de Janeiro, Brazil. Four out of nine fish analyzed (prevalence 44.4%) were parasitized by C. stelliferi and showed a mean intensity of 2.5 (range 2-3, standard deviation 1.25). Adult males of C. stelliferi can be differentiated from their closest congeners based on the combination of the following characters: maxilliped with naked basal segment and small apical spine, the presence of two elements on the second endopodal segment of the antenna, and the presence of leg 4. This parasitic copepod is seemingly host-specific to fish of the family Sciaenidae and its occurrence is restricted to the Brazilian coast. The present results contribute to our knowledge of the biology of C. stelliferi and of the parasitic copepod fauna from Brazil.