New host and ocean records and remarks on the morphology and behavior of Jusheyus shogunus (Copepoda: Siphonostomatoida: Eudactylinidae.

Jusheyus shogunus Deets and Benz, 1987 (Copepoda: Eudactylinidae) is reported from wreckfish, Polyprion americanus (Schneider, 1801) collected from widely separated locations in the north Atlantic. This represents a new host record and new ocean report for this parasite. Examination of male and female copepods allowed some confusion regarding the morphology of J. shogunus to be eliminated. Jusheyus shogunus possesses a cephalothorax rather than a cephalosome and its dorsal styliform processes are connected by an internal bridging sclerite and an external dorsal plate that is hinged to its cephalothorax. Each process also articulates with its own internal ventral sclerite. A series of muscles services these structures, and comparisons of the dorsal styliform processes of J. shogunus with the dorsal stylets of Kroyeria spp. revealed some morphological similarities. Adult female J. shogunus in the study collection varied in size from 2.16 to 4.97 mm total length, and smaller and larger specimens presented somewhat different body forms. Most egg sacs contained multiseriately arranged eggs; however, several specimens possessed a sac whose distal portion contained uniseriately arranged eggs and whose proximal portion contained 2 rows of eggs. Jusheyus shogunus attaches to the gill filament lamellae of its hosts using its second antennae and maxillipeds. The dorsal styliform processes can be erected by either directly raising them or by flexing the cephalothorax at its junction with the first free thoracic segment. In either case the tips of the processes can engage 1 to several lamellae on the adjacent gill filament to help secure the parasite.