Morphological and molecular analyses of Paropecoelus saudiae sp. nov. (Plagiorchiida: Opecoelidae), a trematoda parasite of Parupeneus rubescens (Mullidae) from the Arabian Gulf

Abstract

The Rosy Goatfish (Parupeneus rubescens) is considered to be one of the most common goatfish species in the Arabian Gulf used as seafood on Saudi Arabia’s fish markets. The purpose of this study was therefore to investigate one of the digenean species that infects this species of fish. It has been established that a new plagiorchiid species depends primarily on its morphological and morphometric characteristics within the Opecoelidae family and is classified as Paropecoelus saudiae referring to its host’s location. The present opecoelid species is characterized by having all the generic features within the genus Paropecoelus at morphological and morphometric levels. It could be differentiated from other species within this genus by the proportions of the different body parts, ratios of forebody/hindbody and oral/ventral suckers, location of oral sucker, number of marginal papillae on the ventral sucker, location and number of ovarian lobes, distribution and arrangement of uterine coils, extent of vitelline follicles, shape of seminal vesicle, and the terminal position of the genital pore. Due to the presence of some difficulties in the morphology of the closely related Paropecoelus species, the 18S and 28S rRNA gene-based molecular phylogenetic analysis was selected and analyzed to investigate the phylogenetic affinities and the taxonomic status of the recovered parasite species. The existing Paropecoelus species’ phylogenetic tree revealed a well-resolved distinct clade with other species belonging to The Opecoelidae family and deeply embedded within the Paropecoelus genus. The current study of the Paropecoelus species therefore reflects the third account of this genus as endoparasites of various species of the rosy goatfish.