Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 4, 1997
Publication Date: N/A
Interpretive Summary: Strongyloid nematodes are a major cause of morbidity and mortality in equines in the United States. Resistance to antiparasitic drugs (currently the only means of controlling the nematode disease in horses) is common and alternative control methods for these parasites are needed to protect horses in the United States. Considerable research is underway worldwide to develop improved control strategies. This research requires the identification of the more than 40 species of small strongyles (nematodes of the subfamily Cyathostominae) that are parasitic in the large intestine and caecum of horses. This report provides new information on the type species of the genus Cylicocyclus. The results will be used by researchers worldwide working to control these economically important nematodes.
Cylicocyclus radiatus, the type species of the genus, a rare, but cosmopolitan, species of small strongyle from horses is redescribed to provide the information required for its identification and differentiation from other species of the genus. Type specimens discovered in the British Museum of Natural History were included among the specimens from Equus asinus from Egypt and Equus caballus from Kazakhstan, Ukraine, Panama, Canada, and United States of America that formed the basis for this redescription. Cylicocyclus radiatus is distinguished by its large buccal capsule with relatively thin, straight walls, the absence of a dorsal gutter, inconspicuous leaf crowns, and a small indistinct esophageal funnel. The most similar species is C. triramosus of zebras which can be distinguished by the presence of a dorsal gutter and distinct dorsal and ventral notches in the mouth collar.