The use of ovejector structure in the phylogeny of the Haemonchinae is hampered by differences among nematologists in the application of terminology and the recognition of homologous parts. Some workers recognize a sphincter with 2 parts, but others recognize only the proximal, rounded part of the sphincter and include the distal cylindrical part of the sphincter with the vestibule. The results of this study demonstrate that all sphincters of Haemonchinae of ruminants have 2 parts. To encourage the application of a uniform terminology to homologous parts of the ovejector, we propose the use of the terms “sphincter 1” for the rounded part and “sphincter 2” for the cylindrical part. It is hoped that clarification of the terminology for ovejectors of the Haemonchinae will provide a model useful for improving descriptions of ovejectors throughout the Trichostrongyloidea.

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