Mexicana rubra sp. nov. and Encotyllabe cf. spari Yamaguti, 1934 (Monogenea) of Orthopristis ruber (Cuvier, 1830) from the Brazilian Coast off Rio de Janeiro

sp. nov. and cf. are described from the gills of the marine fish (Haemulidae) caught off Rio de Janeiro, Brazil. Morphological, ultrastructural and genetic data are provided. The main diagnostic features of this new species of ectoparasite are a posteriorly bipartite testis, a ventral bar with three deep bowed projections and a dorsal bar with two deep, conspicuous, antero-lateral indentations. Genetic data on sp. nov. are based on the ITS1, 5.8S and partial 18S and 28S rDNA. This is the sixth known species of Caballero & Bravo-Hollis, 1959, a key to which is also presented. cf. Yamaguti, 1934 is described from the same host, with new ultrastructural data and new partial 18S and 28S rDNA sequences. A phylogenetic analysis based on partial 18S and 28S sequences is undertaken for both species.