An integrative study of morphological and molecular characterization of Diplectanum aequans (Diplectanidae: Monogenea) infecting European sea bass Dicentrarchus labrax (L.) from Turkish coasts

The diplectanid monogenean Diplectanum aequans ( D. aequans ) (Wegener, 1857) is one of the most important ectoparasites in the wild and cultured European sea bass Dicentrarchus labrax ( Dic. labrax ) (Linnaeus, 1758) worldwide. Presently, there is no information on the molecular data of D. aequans from Turkish coasts. In the present study, diplectanid monogeneans were collected from wild and cultured Dic. labrax in the Black Sea (FAO area 37.4.2) and Aegean Sea (FAO area 37.1.3) coasts of Türkiye, morphologically identified, and genetically characterized by sequencing of 28S rRNA and 18S rRNA fragments. The collected diplectanids were unambiguously identified as D. aequans based on detailed morphological features and sequence characterization of partial 28S rRNA and 18S rRNA genes. The overall prevalence and mean intensity of D. aequans were 100% and 15.1, respectively. This study reports first information of molecular (28S and 18S rRNA) evidence of D. aequans from Dic. labrax in the Turkish coasts. The new 18S and 28S rRNA sequences for D. aequans isolated from the Black Sea and Aegean Sea are genetically characterized. The 28S and 18S rRNA sequences of D. aequans can be used to resolve the phylogenetic positions of species found in the family Diplectanidae from the Black and Mediterranean Sea.