Four new species of Colobomatus (Copepoda: Philichthyidae) parasitic in the lateral line system of marine finfishes captured off the Ryukyu Islands, Japan, with redescriptions of Colobomatus collettei Cressey, 1977 and Colobomatus pupa Izawa, 1974

This study describes four new species of Colobomatus Hesse, 1873 and redescribes Colobomatus collettei Cressey, 1977 and Colobomatus pupa Izawa, 1974 based on females collected from the sensory canals of seven finfish species from off the Ryukyu Islands, southern Japan. Colobomatus pteroisi sp. nov. from Pterois volitans is unique in having a mid-lateral pair of cephalic processes; Colobomatus acanthuri sp. nov. from Acanthurus olivaceus possesses a short neck between the head and first pair of thoracic processes and tiny spinules and three claws apically on the cephalic, thoracic and genital processes; Colobomatus gymnocranii sp. nov. from Gymnocranius griseus has an anterior pair of papillose thoracic processes that are twice as long as the posterior pair of spinulose processes; Colobomatus absens sp. nov. from Pterocaesio digramma is unique in lacking a posterior pair of thoracic processes. New host and locality records for C.collettei and C.pupa are also reported herein.