Light and Scanning Electron Microscopy of Cainocreadium epinepheli (Digenea: Opecoelidae) and Prosorhynchus serrani (Digenea: Bucephalidae) From Two Economically Important Serranid Fishes from the Red Sea in Egypt

Abstract

The present study recorded the adult stages of two digenetic trematodes from the anterior part of the alimentary canal and pyloric caeca of two commercially important marine bony fishes belonging to the family Serranidae from the Red Sea in Egypt. They are opecoelid Cainocreadium epinepheli (Yamaguti, 1934) Durio and Manter, 1968 and Bucephalid Prosorhynchus serrani Durio and Manter, 1968 that infect areolate grouper, Epinephelus areolatus and yellow-edged lyretail, Variola louti, respectively. The incidence of infection is reported as 55.5% (5/9) for Cainocreadium epinepheli and 81.2 % (13/16) for Prosorhynchus serrani. The body of Cainocreadium epinepheli measured 2.003-3.667 (2.809) × 0.651-1.338 (0.986) (length × maximum width) while the body of Prosorhynchus serrani measured 1.664-2.210 (1.750) × 0.225-0.358 (0.287). Cainocreadium epinepheli is characterized by the presence of smooth tegument, median gonopore in the forebody, canalicular seminal receptacle, claviform cirrus sac, long excretory vesicle reaching forebody, pre-testicular intercaecal uterus, lobed ovary, non-filamentous eggs and has an extension of vitellaria into forebody. On the other hand, Prosorhynchus serrani devoids the oral and ventral suckers but has a single caecum, midbody-located mouth, conical rhynchus, pre-testicular ovary, and elongated seminal vesicle with curved proximal part of pars prostatica. The internal organs, body regions, and their ratios concerning total body length for both species were described, measured, and compared with some of the previously described species. Finally, this study postulates that it is the first time for studying surface topography using scanning electron microscopy of both species in Egypt.