Redescription of Diclidophoroides maccallumi (Monogenea: Diclidophoridae) from the gills of longfin hake, Phycis chesteri, from the Gulf of St. Lawrence

Diclidophoroides maccallumi is redescribed from the gills of longfin hake, Phycis chesteri, caught off the coast of Newfoundland in the Gulf of St. Lawrence. Specific characteristics such as the number of genital corona spines and morphometric measurements are within the range limits given in previous descriptions of this species from red hake, Urophycis chuss. The detailed morphology of the clamp, the male genital terminalia, and the female reproductive system is presented. This redescription confirms the restoration of Diclidophoroides Price, 1943 (sensu Mamaëv, 1976) as a primitive genus in the subfamily Diclidophorinae. The generic diagnosis of Diclidophoroides should be emended to include the following: in the male genital terminalia, the presence of a prostatic vesicle, and in the clamp, the presence of a partially developed lamellate extension, b, originating from median sclerite a1, with distal attachment to the terminal half of peripheral sclerite c1, with no proximal border between sclerites a2 and c2, and the presence of a sucker in the inner side. Major generic characteristics that differentiate the genera Diclidophoroides and Diclidophora are briefly discussed. The occurrence of Diclidophoroides maccallumi on Phycis chesteri in the Gulf of St. Lawrence represents a northern range extension of the parasite and a new host record, and provides further evidence for the close phylogenetic affinity between Phycis chesteri and the genus Urophycis.