The genus Capillospirura Skrjabin, 1924 (Nematoda: Cystidicolidae) of sturgeons

Abstract

Capillospirura Skrjabin, 1924 (Nematoda: Cystidicolidae) is redefined on the basis of a study of specimens from old world sturgeons. It can be distinguished from the closely related Ascarophis van Beneden, 1870 by a bidentate plate-like structure which arises from the anterolateral wall of the buccal cavity. Capillospirura is also characterized by narrow pseudolabia with a ridge-like apex, submedian labia, and sublabia in subdorsal and subventral quadrants of the oral opening. Three species are assigned to Capillospirura: C. ovotrichuria Skrjabin, 1924 and C. argumentosa (Skrjabina, 1966) n. comb. (= Ascarophis argumentosus) from old world sturgeons and C. pseudoargumentosa (Appy and Dadswell, 1978) n. comb. (= Caballeronema pseudoargumentosus) from a new world sturgeon. The value of cephalic structure in cystidicolid taxonomy is discussed.