Morphological and molecular characterization of Chauhanellus peruvianus sp. nov. (Dactylogyridea, Dactylogyridae) from Galeichthys peruvianus (Siluriformes, Ariidae) in the Southern Pacific Ocean

A new species of Chauhanellus Bychowsky & Nagibina, 1969 is described from the gills of the Peruvian sea catfish, Galeichthys peruvianus Ltken (Siluriformes, Ariidae), collected from the Southern Pacific Ocean off the coast of Peru. The description of the new species is based on an integrative taxonomic approach, incorporating morphological data, 28S rDNA sequencing, and phylogenetic analysis. Chauhanellus peruvianus sp. nov. can be distinguished from all its congeners by possessing a tubular MCO with proximal and distal curvatures and a spear-shaped distal extremity, as well as an elongated, grooved accessory piece that is proximally expanded and distally hook-shaped. Phylogenetic analyses based on 28S rDNA sequences recovered C. peruvianus sp. nov. in a clade with C. boegeri Domingues & Fehlauer, 2006 and an unidentified Chauhanellus species from Genidens genidens (Cuvier), forming a well-supported Neotropical lineage. However, the genus Chauhanellus was recovered as non-monophyletic, with a separate Indo-Malayan lineage comprising seven species. The description of C. peruvianus sp. nov. represents the first record of Chauhanellus in the Southeastern Pacific and raises the number of species reported from South America and globally to eight and 32, respectively.