Amphistomes as species markers of the serrasalmid fish, Myleus ternetzi (NORMAN), from French Guiana, with descriptions of two new species and one new genus

Abstract

Two new species of amphistome (Trematoda) are described from "pacu", Myleus ternetzi, from French Guiana. For one of these, a new genus is proposed. Additionally, a common species, Pseudocladorchis cylindricus, is reported. Pacudistoma guianensis sp. nov. is a robust form with a massive pharynx; a large genital sucker; long, convoluted ceca; and a subterminal acetabulum that is smaller than the genital sucker. Myleustrema concavatum gen. et sp. nov., on the other hand, has a slender, flattened body, concave dorsally; a small pharynx; no genital sucker; ceca that are short, slender, and nearly straight; and a small, terminal acetabulum which is provided with papillae. The two new forms seem to be highly host specific and could therefore be used as biological markers.