Redescription of five known species of Hatschekia Poche, 1902 (Copepoda, Siphonostomatoida, Hatschekiidae) parasitic on Japanese tetraodontiform fishes, with discussion on sexually dimorphic features in the genus

Abstract

Abstract Five known species of Hatschekia Poche, 1902, parasitic on the branchial lamellae of Japanese tetraodontiform fishes, are redescribed. They are H. monacanthi Yamaguti, 1939, H. bibullae Uyeno & Nagasawa, 2010, H. kuroshioensis Uyeno & Nagasawa, 2010, H. ostracii Yamaguti, 1953, and H. legouili Nuñes-Ruivo, 1954. The males of H. bibullae and H. legouili, free-living larval stages of H. bibullae reared from eggs, the copepodid IV female of H. kuroshioensis, and both sexes of copepodids III-V of H. legouili are described for the first time. The antenna, the postantennal process, the length of the caudal ramus, and the ornamentation of the dorsal shield of the cephalothorax, if present, are sexually dimorphic within the genus. By showing these sexually dimorphic features of the male, it is inferred that both sexes of copepodid II-IV and copepodid V male, have attributes of the male.