Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 24, 2002
Publication Date: October 31, 2002
Citation: LICHTENFELS, J.R., PILITT, P.A., GIBBONS, L.M., HOBERG, E.P. REDESCRIPTIONS OF HAEMONCHUS MITCHELLI AND HAEMONCHUS OKAPIAE (NEMATODA: TRICHOSTRONGYLOIDEA). JOURNAL OF PARASITOLOGY. 88:947-960. 2002. Interpretive Summary: Species of the genus Haemonchus are pathogens of cattle, sheep, and goats, causing significant production losses due to morbidity, mortality, cost of treatment and suboptimal use of contaminated pastures. This report provides modern descriptions for 2 species of Haemonchus, previously indistinguishable from each other, from African ruminants. This study is part of an effort to improve the capability to identify, and develop a predictive phylogeny for, all species of this economically important genus that includes emerging threats to ruminant farming in North America. The information will improve the ability to identify endemic and exotic species that threaten economically important hosts, to evaluate biological and chemical treatment and control agents, determine the importance of reservoir hosts such as wildlife, evaluate emerging or imported pathogens and to prevent the importation of others.
Technical Abstract: In the course of revision of the nematode genus Haemonchus Cobb, 1989, commonly referred to as large stomach worms, significant new morphological information was discovered that allows the recognition of 2 species previously believed to be synonymous for more than 50 years. Both species, Haemonchus mitchelli Le Roux, 1929 from the eland, Taurotragus oryz, and other African ruminants; and, H. okapiae van den Berghe, 1937 from the okapi, Okapia johnstoni, have a synlophe of 42 ridges, but the synlope of H. mitchelli is longer than that of H. okapiae. The distal tip of the left spicule of H. mitchelli males bears a barb that is about twice as long as the short barb and half as long as the long barb on the right spicule. In contrast the barb on the left spicule of H. okapi males is similar in size to the short barb and about 25% as long as the long barb of the right spicule. The dorsal ray of H. mitchelli is bifurcated distally for 25-39 (32)% of its length and its stem is expanded proximally, but the dorsal ra of H. okapiae is bifurcated 37-50 (42)% and its stem is of uniform thickness.