Parasitology, Harold W. Manter Laboratory of

 

Date of this Version

1991

Comments

Published by Lichtenfels & Pilitt in Journal of the Helminthological Society of Washington (1991) 58(2).

Abstract

Ostertagia bisonis Chapin, 1925, is an abomasal worm of the American buffalo, Bison bison, and other ruminants including cattle in which it can cause clinical nematodiasis. This report describes characteristics of O. bisonis, especially details of the synlophe and esophagus, that are necessary for constructing a key to the species of medium stomach worms (Ostertagiinae) parasitic in domestic ruminants in North America. The synlophe of O. bisonis is most similar to the single ridge tapering lateral synlophe of Ostertagia ostertagi. Ducts of the subventral glands of the esophagus empty anterior to the cervical papillae and the esophageal-intestinal valve is more than twice as long as wide. We follow earlier workers in considering Ostertagia orloffi Sankin, 1930, a synonym of O. bisonis. Ostertagia bisonis may have more generalized characters than any other species with a tapering lateral synlophe that are parasites of domestic ruminants in North America, but polarization of some characters cannot be considered reliable until additional outgroups are studied.

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