Abstract
The pleopod morphology of eleven species of parasitic isopods from Brazilian fish was compared. Ten
species of Cymothoidae were studied, as follows: Asotana magnifica THATCHER, 1988; Artystone minima
THATCHER & CARVALHO, 1988; Braga cichlae SCHIöDTE & MEINERT, 1881; Braga nasuta
SCHIÖDTE & MEINERT, 1881; Braga patagonica SCHIöDTE & MEINERT, 1884; Braga spp. 1 & 2;
Riggia brasiliensis SZIDAT & SCHUBART, 1960; Telotha henselii (VON MARTENS, 1869); and
Nerocila orbignyi (GUERIN-MENEVILLE, 1832). All of these species are from freshwater in the Brazilian
Amazon except for N. orbignyi which is marine. The pleopods of Excorallana berbicensis BOONE, 1918,
a freshwater representative of the family Excorallanidae, were also studied. The pleopods of the cymothoid
species are individually characterized. Pleopod morphology is shown to be useful in defining species and
genera. The evolution of the "appendix masculinum" from a reproductive structure to an accessory gill is
also indicated.
