NEW DATA ON THE MORPHOLOGY AND SYSTEMATIC STATUS OF KLOSSINEMELL-IHERINGI (NEMATODA, ATRACTIDAE) FROM AN AMAZONIAN SERRASALMID FISH

The morphology of the nematode Klossinemella iheringi (Travassos, Arti gas et Pereira, 1928), the type species of the genus Klossinemella Cos ta, 1961, was studied using specimens collected from the serrasalmid f ish, Mylesinus paraschomburgkii Jegu, Santos et Ferreira, 1989 (a new host record), from the Trombetas River, Para State, Brazil, by both li ght and scanning electron microscopy. This species was also recorded f rom the Jari River (Para State), the Uatuma, Pitinga and Capucapu Rive rs (Amazonas State), and the Araguari River (Amapa State). An examinat ion by SEM made it possible, for the first time in this genus, to stud y in detail the structure of the cephalic end. Characteristic features are the presence of 8 cephalic papillae arranged in two circlets, wel l developed lateral amphids, and especially a crown of 8 cephalic, Y-s haped sclerotized pieces (outgrowths). The male possesses 8 pairs of c audal papillae (3 preanals, 1 adanal and 4 postanals), two unequal spi cules (0.156-0.294 mm and 0.069-0.099 mm long) and a gubernaculum (0.0 27-0.045 mm in length); previously undescribed deirids were also found . This is the first record of this parasite from the Amazon River basi n. The genus Proatractis G. Caballero, 1971 is considered a synonym of Klossinemella Costa, 1961, belonging to the cosmocercoid family Atrac tidae, and its type species is transferred to the latter genus as Klos sinemella parvicapiticoronata (G. Caballero, 1971) comb. n.