Sciadicleithrum spp. (Dactylogyridae, Monopisthocotyla) parasitizing Saxatilia brasiliensis (Cichlidae, Cichliformes) from the Munim River Basin, northeastern Brazil, with a description of a new species

During a study conducted on the helminth fauna of fishes in the middle Munim River Basin, Maranhão State, northeastern Brazil, a new species of Sciadicleithrum , S. anapurusensis sp. nov. , is reported from the gills of Saxatilia brasiliensis (Bloch, 1792), a cichlid endemic to the Northeast region of Brazil. In addition, a known species, Sciadicleithrum araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016, was recovered from the same host and is redescribed here, providing new morphological and biogeographical data. Sciadicleithrum anapurusensis sp. nov. differs from all congeneric species in the general morphology of sclerotized structures (anchors, bars, vagina, accessory piece, and the number of MCO rings), being mainly characterized by the bifurcated accessory piece with unequal branches at the distal portion, with a subterminal thin projection and a hook-shaped terminal end. The findings of this study emphasize the importance of carrying out comparable surveys on different host species in order to increase the knowledge on monopisthocotylan parasites of fishes in this area. Furthermore, the finding of two congeneric species in the same host species reinforces the host specificity of Sciadicleithrum species to cichlid hosts.