Assessing the taxonomic status of an opecoelid trematode from the evileye blaasop, Amblyrhynchote honckenii (Bloch), in South Africa

The taxonomic status of Pseudoheterolebes cotylophorus (Ozaki 1935) Yamaguti 1959 (Opecoelidae: subfamily Opistholebetinae) has been a subject of taxonomic confusion since its initial description by Ozaki in 1935 as Opistholebes cotylophorus Ozaki 1935 from diodontid fish in Japan. The species' current recognised classification dates back to Yamaguti's reclassification of O. cotylophorus as Pseudoheterolebes cotylophorus; however, doubts persist regarding this classification and the validity of this species. The species was reported by Bray in 1986 from off the coast of South Africa, based on a single specimen infecting the evileye blaasop, Amblyrhynchote honckenii (Bloch) (Tetraodontidae). However, recently, this report from the South African coastline was considered doubtful. Parasitological assessments of South African marine fishes provided the opportunity to recollect this taxon from the same host species reported by Bray, allowing a reassessment of its taxonomic status. Morphological and molecular phylogenetic analyses, incorporating ITS2 and 28S rDNA, as well as cox1 and nad1 mtDNA sequence data, support the identification of the South African material as Opistholebes cf. amplicoelus; demonstrating both the value of molecular approaches in the identification and classification of marine parasites and the need for additional life-cycle data to fully resolve species boundaries.