The North and Central American Species of Rhabdochona Railliet 1916 (Nematoda: Rhabdochonidae) of Fishes, Including Rhabdochona canadensis sp.nov.

Abstract

The systematics of the representatives of the genus Rhabdochona, parasitic in fishes of North and Central America, is revised. Rhabdochona cascadilla Wigdor 1918, R. kidderi Pearse 1936, R. decaturensis Gustafson 1949, R. cotti Gustafson 1949, R. ovifilamenta Weller 1938, R. milled Choquette 1951, and R. canadensis sp.nov. are considered as the valid species of this region. The first six species are redescribed and illustrated. The new species, R. canadensis, is described from the cyprinids Hybopsis gracilis (flathead chub; type host), H. plumbea (lake chub), and Rhinichthys cataractae (longnose dace) of Alberta; the latter form is characterized largely by the presence of one or two long filaments at each pole of the eggs, by 14 teeth in the prostom, by the presence of the cuticular spike at the tip of the tail, and by the character of the spicules. The species R. pellucida Gustafson 1949 is regarded as a synonym of R. cascadilla Gustafson 1949, and R. laurentiana Lyster 1940 as a synonym of R. ovifilamenta Weller 1938. Rhabdochona serrata (Wright 1879) Ko and Anderson 1969 is transferred to the genus Cystidicola as species inquirenda. The hosts and geographical distribution of the current members of the genus are reviewed. The paper is supplemented by a key for the identification of the species parasitic in fishes of North and Central America.