Neocucullanus neocucullanus Travassos, Artigas et Pereira, 1928 (Nematoda: Cucullanidae) from the Characidae fish, Brycon hilarii Valenciennes, 1850, from Brazil

Abstract

During investigation on the helminth parasites from (Caspeta-Mandujano et al. 2005). N. multipapillatus Petter, 1989 was detected in Paraná River basin, Arroyo, Tagatija-guazu, Conception Province, Paraguay (Petter 1989). According to Petter (1989) N. multipapillatus differs from N. neocucullanus mostly by the absence of small caudal alae and the presence of one unpaired precloacal papilla on the male posterior extremity. A detailed study of the material collected in the present work, including scanning electron microscopy (SEM), allowed to identify these nematodes as N. neocucullanus and to confirm N. multipapillatus as a junior synonym of N. neocuccullanus. MATERIALS AND METHODSFish specimens (n = 60) were captured from River Juba (14º 50'09.9''S and 57º51'13.5''W), Tangará da Serra, state of Mato Grosso, Brazil, from August 2003 to January 2004, by fishing rods. Fishes were deep-frozen after capture and dissected in the laboratory. Nematodes recovered from digestive tract were washed in physiological saline, fixed in 5% formalin and stored in 70% ethanol. microscope examination, nematodes were cleared in glycerine. Drawings were made with the aid of a Zeiss microscope drawing attachment using Nomarski's interference contrast. Two specimens (one male and one female) were dehydrated through a graded ethanol series, critical point dried, coated with gold and examined in a SEM. RESULTS Neocucullanus neocucullanus (Figs 1-2)Description -Large sized nematodes without lateral alae. Oral opening elongated dorsoventrally surrounded by membranous collarette with row of numerous denticles. Nerve ring, excretory pore (observed in one specimen) and deirids 0.41-0.47 mm, 0.71 mm, and 0.65-0.82 mm, respectively, from anterior extremity. Precloacal sucker present, situated 1.00-1.30 mm from posterior extremity. 14 pairs of caudal papillae: 10 preanal (3 pairs subventral and anterior to sucker; 3 pairs subventral at level of sucker; 2 pairs subventral posterior to sucker; and 2 pairs subventral between unpair median preanal papilla and anal aperture) and 4 postanal (3 subventral and 1 lateral). Unpair median preanal papilla proeminent. Spicules broad 0.49-0.73 mm long, with rounded and moderately scerotized distal ends. Gubernaculum absent. Tail rounded 0.19-0.32 mm long with terminal mucron.