Two New Acanthocephalans from Neotropical Fishes: Neoechinorhynchus prochilodorum sp. n. and Gorytocephalus plecostomorum gen. et sp. n.

Abstract

Dying bocachicos, Prochilodus reticulatus, from the Sonso Reservoir at Valle, Colombia, were infected with Neoechinorhynchus prochilodorum sp. n. The new species has a proboscis which averages 83 , long. Hooks of the apical circle are 55 t, long, those of the middle circle 41, and those of basal circle 30. N. prochilodorum is distinguished from all previously described species of Neoechino- rhynchus except N. coiliae Yamaguti, 1939, and N. hutchinsoni Datta, 1936, by its proboscis hook lengths and its small proboscis. N. prochilodorum has a shorter, stouter trunk with a shorter neck and longer lemnisci than N. coiliae. Lack of sexual dimorphism in body size, lack of a trunk construction in males, and possession of lemnisci that reach the level of the anterior testis distinguish N. prochilodorum from N. hutchinsoni. Five of 7 specimens of the armored catfish, Plecostomus plecostomus, collected from the Rio Cardenas, Panama, R. P., were infected with from 1 to 7 specimens of Gorytocephalus plecostomorum gen. et sp. n. Gorytocephalus is a member of the subfamily Neoechinorhynchinae of the family Neo- echinorhynchidae. It differs from other genera of the subfamily in possession of a prominent muscular sling surrounding the proboscis receptacle and by the arrangement of the proboscis hooks. Goryto- cephalus plecostomorum is also characterized by a tall (750 ,) dorsal crest extending the entire length of the trunk. Neoechinorhynchus spectabilis Machado, 1959, is tentatively assigned to Gorytocephalus.