DNA evidence that Marshallagia marshalli Ransom, 1907 and M. occidentalis Ransom, 1907 (Nematoda: Ostertagiinae) from Svalbard reindeer are conspecific.

The gastro-intestinal parasitic nematodes of ruminants Marshallagia marshalli and M. occidentalis are morphs of a single species according to indirect evidence. In this study, their taxonomic status and molecular identification were assessed more directly in isolates from the abomasal nematode community of Svalbard reindeer using genetic data. DNA sequences of the first and second internal transcribed spacers of nuclear ribosomal RNA genes were obtained from individual nematodes by the polymerase chain reaction (PCR). Both taxa contained virtually identical sequences of each ITS and shared most of the polymorphisms detected. A PCR assay based on ITS-2 sequences previously developed to identify M. marshalli and Ostertagia gruehneri, the second common species in this community, gave identical results for M. marshalli and M. occidentalis. Genetic data thus confirmed that M. marshalli and M. occidentalis are conspecific.