Site adaptations of Acanthogyrus (Acanthosentis) tilapiae: observations through light and scanning electron microscopy

Morphomolecular identification and considerations of the infestation site adaptations of Pricea multae (Thoracocotylidae: Priceinae) from Scomberomorus commerson, off Arabian Gulf, Saudi Arabia

Monogeneans Pricea multae naturally infested 42 of the 120 (35%) mackerel fish (Scomberomorus commerson) examined. For the first time, an infestation was discovered off the coast of Jubil in the Arabian Gulf of Saudi Arabia. Based on the structure clarified through light and electron microscopy of mounted specimens and molecular analysis of rDNA and measurements of this monogenean parasite was identified as P. multae. The tegumental surface of the parasite was characterized by tegumental ridges running transversally, generating folds in both the dorsal and ventral surfaces of the body at regular intervals. The study clarified the importance and function of the micro-structures, such as tegumental folds, perforations, sensory ganglia present on the parasite's surface, and the larger hamulus supported by a relatively unmodified internal spine. This monogenean parasite has adapted to its host infestation site uniquely.

Scanning morphology, prevalence and histopathology of some acanthocephalans infecting some River Nile fish

Acanthocephalan morphology and their adverse pathological impact on fish are of great concern. Two species of acanthocephalans were recorded from 800 samples of live freshwater fish collected randomly during 2017–2018 from Lake Nasser, Aswan, Egypt. The recovered species were identified morphologically as Acanthogyrus (Acanthosentis) tilapiae from three Tilapia spp. (Sarotherodon galilaeus, Oreochromis niloticus and Tilapia zillii) and Rhadinorhynchus niloticus from Lates niloticus. The intensity of parasitic infection and the seasonal prevalence were higher in L. niloticus than in Tilapia spp. The clinical signs and post mortem lesions of infected fish were reported. Morphological description of the detected parasites using light microscope was then confirmed by electron microscopy to amplify ambiguous details. The histopathological findings of the intestine of naturally infected fish with acanthocephalan parasites were investigated and described. The main damage caused by them is destruction of the mucosal epithelium of the villi, necrosis and degeneration of intestinal epithelial cells.