Acanthocephala of South American Fishes. Part I, Eoacanthocephala

Abstract

Paracavisoma impudica (Diesing, 1851) Kritscher, 1957, is redescribed from Pseudodoras niger from Peru. It is characterized by having 42 to 48 longitudinal rows of 23 to 27 proboscis hooks. Errors in previous descriptions of this species are corrected. Pomphorhynchus yamagutii sp. n. is described from Percichthys melanops from Chile. It has 12 to 14 longitudinal rows of 9 to 10 proboscis hooks. It is close to P. sebastichthydis but differs in having stouter hooks, shorter hooks in the basal circle, and a much shorter neck in proportion to the trunk. This paper is the last report on the Acanthocephala collected from fishes by the second author in South America during a National Science Foundation study trip in 1968-69. Specimens were fixed in 10% formalin and stained with carmine for study. All measurements are in microns unless otherwise stated. Class Palaeacanthocephala Meyer, 1931 Order Echinorhynchida Southwell et Macfie, 1925 Family Echinorhynchidae Cobbold, 1879 Paracavisoma impudica (Diesing, 1851) Kritscher, 1957 (Figs. 1-4) Four females, three gravid and one immature, were recovered from an armored catfish, Pseudodoras niger, in Peru. Because of an error in hook number reported by Kritscher (1957), and because he did not illustrate the female, we redescribe the female here. Description Proboscis (Fig. 1) claviform, widest near anterior end, narrow posteriorly. Hooks (Fig. 2) numerous, closely spaced in 45 to 48 longitudinal rows of 23 to 27 each. Basal 10 to 12 rootless spines, each with anterior manubrium; remaining hooks with well-developed roots. Anterior hooks slender, 30 to 40 long, middle hooks stout, 50 to 56 long, basal spines slender, most with recurved tips, 44 to 50 long. Neck 140 to 210 long, 400 to 415 greatest width at base. Trunk slender, slightly wider in anterior half, unarmed. Lemnisci flat, equal, distal ends about at level of posterior end of proboscis receptacle, which is double-walled, with brain at posterior end. Genital pore subterminal. Female (Fig. 3): 12.5 to 14.3 mm long, 1.0 to 1.2 mm greatest width. Proboscis 1.2 to 1.3 mm long, 615 to 625 greatest width. Neck 140 to 210 long, 400 to 415 wide at base. Lemnisci Received for publication 27 April 1973. * Department of Biology, University of Northern Colorado, Greeley, Colorado 80639. t Department of Entomology-Zoology, South Dakota State University, Brookings, South Dakota 57006. 1.5 to 1.85 mm long. Proboscis receptacle 1.85 to 1.95 mm long, 350 to 500 wide. Uterine bell about 1.95 mm from posterior end. Eggs (Fig. 4) 85 to 90 by 12 to 14, with polar elongations of middle shell. Anterior end of acanthor conspicuously spined. Host: Armored catfish, Pseudodoras niger (Valenciennes), Doradidae. Location: Small intestine. Locality: Ucayali River, Pucallpa, Peru. Specimens deposited: USNM Helm. Coll. No. 72769.