Dactylogyrids (Platyhelminthes: Monogenoidea) from the gills of Hassar gabiru and Hassar orestis (Siluriformes: Doradidae) from the Xingu Basin, Brazil

Abstract

Four species of Cosmetocleithrum(three new) and one new species of Vancleaveusare described or reported parasitizing the gills of doradid catfishes (Siluriformes) from Xingu River and related tributaries: Cosmetocleithrumphryctophallussp. nov. and CosmetocleithrumbifurcumMendoza-Franco, Mendoza-Palmero & Scholz, 2016 from Hassarorestis; Cosmetocleithrumleandroisp. nov. from Hassargabiru; Cosmetocleithrumakuandubasp. nov. and Vancleaveusklassenisp. nov. from Hassarorestisand H.gabiru. Cosmetocleithrumphryctophallussp. nov. differs from its congeners by possessing a male copulatory organ (MCO) with 2 ½ counterclockwise rings, and an accessory piece with an elongate torch-shaped blade. Cosmetocleithrumleandroisp. nov. has a MCO comprising a coil of about 3 ½ rings, a sigmoid accessory piece with a cup-shaped distal portion, a single type of hooks, and anchors with poorly differentiated roots. Cosmetocleithrumakuandubasp. nov. is characterized mainly by having a J-shaped MCO, an elongate accessory piece with sharp distal region, distal portion with a small gutter, and a heavily sclerotized vagina with short “S”-shaped vaginal canal. Vancleaveusklassenisp. nov. differs from the other species of the genus occurring in doradids by possessing anchors with triangular to subtriangular superficial root, developed deep root, and a coiled MCO with 2 ½ counterclockwise rings. Cosmetocleithrumbifurcumwas reported for the first time parasitizing doradids from Brazilian Amazon.