First report of Nematodirus battus (Nematoda: Trichostrongyloidea) in North America: redescription and comparison to other species.

Abstract

Nematodirus battus Crofton and Thomas, 1951 from sheep is reported for the first time in North America. Nematodes of this species were recovered from the small intestine of sheep born and raised in the Willamette Valley of western Oregon. Previously, N. battus was believed to have a geographic distribution limited to the British Isles and smaller foci in Europe where it is recognized as a significant pathogen in lambs. The presence of this nematode, exotic to North America, is consequently of great importance because of its potential negative economic impact. Specimens of N. battus can be distinguished from those of related species found in North America by the structure of the synlophe in both sexes, the form of the copulatory bursa and terminal portion of the spicules in males, and the form of the tail in females. It is likely that N. battus in sheep will most often occur in mixed infections with N. filicollis and N. spathiger. Nematodes identified as Nematodirus battus Crofton and Thomas, 1951 were recovered from the small intestines of sheep (mixed breed), Ovis aries Linnaeus, at Oregon State University dur- ing a routine anthelminthic trial. Animals found to be infected had been locally raised in the Wil- lamette Valley of western Oregon, thus estab- lishing the endemic source of infection. Prior to the present study, N. battus had not been found outside of the western Palearctic. The presence of this species, exotic to North America and the Western Hemisphere, is notable and of signifi- cance beyond the apparent new geographic rec- ord. Nematodirus battus was originally described