A new species of Characithecium (Monogenea: Dactylogyridae) from external surface and gills of two species of Astyanax (Ostariophysi:Characidae) in southern Brazil

Abstract

A new species of Characithecium, a genus of monogenean parasites of Neotropical characids, is described from specimens collected on the bodysurface and gills of Astyanax aff. fasciatus and Astyanax jacuhiensis from Lake Guaíba, State of Rio Grande do Sul, Brazil. The new species issimilar to Characithecium costaricensis, but differs by having the haptor separated from the body by a long peduncle, and by having an accessorypiece composed of 2 subunits in the male copulatory complex – 1 ventral pincer-shaped at the distal end, and 1 dorsal with an expanded rod-shapedproximal end and the distal end containing 3 elongated projections–, and the dorsal bar usually presenting a small median elevation in the anteriormargin. This study increases the number of species of Characitecium to 7 and expands our knowledge on the diversity of monogenean parasitesof characids.