Morphological and molecular characterization of Rhadinorhynchus sp. from the Nile perch Lates niloticus (Linnaeus),...

Previous studies revealed a systematic misunderstanding on the nomenclature of Rhadinorhynchus niloticus, where two different species shared the same scientific name: R. niloticus Meyer, 1932 and R. niloticus Mohamadain, 1989. Rhadinorhynchus sp. of the present study were collected from the intestine of Lates niloticus (Linnaeus) in Egypt, and examined using scanning electron microscopy and ITS Ribosomal RNA analysis. The results revealed specific characteristics concerning the number and arrangement of proboscis hooks, body spination in the adult and, for the first time, in the juvenile. The findings of the present parasite were compared with the previously described related species including Tenuisentis niloticus (Meyer 1932) (previously identified as R. niloticus Meyer, 1932). The presence of trunk spines, specific proboscis hooks number, double-walled proboscis receptacle, leminci shorter than receptacle, tubular cement glands and egg shape definitively exclude our specimen from being T. niloticus, as this genus has different characters. Moreover, the results obtained from the molecular analysis confirmed the genetic difference. Further studies are needed to verify if the present specimen is a new species. A single worm has been found hyperparasitized by clusters of rod-shaped bacteria attaching to the tegument; this may be considered as the first record of bacterial hyperparasitism and their associated pathology on Acanthocephala. Granulomatous lesions and some necrosis associated with tegumental disintegration have been encountered. Future collaborative research is suggested that leads to the potential use of bacteria as a means of biological control to Acanthocephalan infections.