Molecular evidence and morphological aspects of Transversotrema licinum, Phyllodistomum hoggettae, and re-description of Gyliauchen volubilis (Digenea) from the Red Sea

During a recent survey on digenean parasites infecting marine fish captured from water located along the Red Sea off Gizan Coasts, Saudi Arabia, thirty-two (29.09%) out of 110 fish were naturally infected with three different species of digenean parasites. The taxonomical status of the recovered worms was confirmed by light microscopy and molecular analysis. Transversotrema licinum infecting the Haffara seabream Rhabdosargus haffara possessed a transversely elongated body with eyespots and the anterior body margin with delineated velum along with its entire breadth. Oral sucker was absent, and eyespots were paired anterior to or at the level of ventral sucker. Phyllodistomum hoggettae from the urinary bladder of the Arabian Nagil Plectropomus areolatus was differentiated by its elongated body, narrow anterior end widened as going posteriorly with prominent marginal undulations in the hindbody. Gyliauchen volubilis infecting the marbled spinefoot Siganus rivulatus, was with fleshy body, conical, tapered anteriorly, convex dorsally, and concave ventrally. Prepharynx was very long and convoluted and had occupied the greater part of the anterior half of the body. Multiple sequence alignment and phylogeny were based on maximum likelihood analysis for the ITS–2 and 28S rDNA for Transversotrema licinum and Phyllodistomum hoggettae were constructed, respectively. They were compared to species within their families and further deposited into the Genebank under accession numbers MG 722711 and MG722710, respectively.