Description of <i>Pseudobenedeniella johnstoni</i> sp. n. (Monogenea: Capsalidae) from the gills of Antarctic black rockcod, <i>Notothenia coriiceps</i> Richardson in coastal waters of West Antarctica

Morphological and metrical analyses of monogeneans from the gills of Antarctic rockcod <i>Notothenia coriiceps</i> revealed the presence of a new species, <i>Pseudobenedeniella johnstoni</i> sp. n. Fresh specimens of monogeneans collected from <i>N. coriiceps</i> from the vicinity of Galindez Island, Argentine Islands, West Antarctica were examined morphologically, by molecular analysis and Energy Dispersive X-ray analysis (EDXA). The new species differs from <i>Pseudobenedeniella branchialis</i> Timofeeva, Gaevskaya, Kovaljova, 1987 by the different shapes of anterior and posterior hamuli, the presence of a pronounced sickle-shaped blade of the anterior hamulus and its characteristic wide (wing-like) shaft, serrated on one side, smaller posterior hamulus with a distinct short and broad shaft that widens and is serrated distally, more extensive dimensions of the penis and its pear-like shape, smaller vagina diameter, ovoid egg shape with more pointed anterior pole and blunt posterior pole and long coiled filament as well as different type species of the host in a geographically distant type locality. Genetic data accompanied the description, and phylogenetic analyses inferred that the new species clustered with monogenean species positioned under the family Capsalidae. Molecular data were generated for the 18S and 28S genes of the ribosomal RNA of <i>P. johnstoni</i> sp. n. to provide the first molecular analysis for <i>Pseudobenedeniella</i> species. EDXA for a species of <i>Pseudobenedeniella</i> was offered for the first time.