Serendipitous discovery of a novel protostrongylid (Nematoda: Metastrongyloidea) in caribou, muskoxen, and moose from high latitudes of North America based on DNA sequence comparisons

Fecal samples are often the only feasible means to assess diversity of parasites in wildlife; however, definitive identification of egg or larval stages in feces by morphology is rarely possible. We determined partial sequences from the second internal transcribed spacer region (ITS-2) of nuclear ribosomal DNA for first-stage, dorsal-spined larvae (DSL) in feces from caribou (Rangifer tarandus tarandus(L., 1758), Rangifer tarandus caribou(Gmelin, 1788), Rangifer tarandus grantii (Allen, 1902)), muskoxen (Ovibos moschatus moschatus(Zimmermann, 1780), Ovibos moschatus wardiLydekker, 1900), moose (Alces alces gigas Miller, 1899 and Alces alces andersoni Peterson, 1952), and from the tissue of one slug (Deroceras laeve (Muller, 1774)) in Arctic-Subarctic North America. A previously uncharacterized, genetically distinct species was recognized based on sequences of 37 DSL from 19 ungulate hosts and the slug. Sequence similarity among in- dividuals of this novel species was 91%-100%. For many individual DSL, paralogues of ITS-2 were detected. ITS-2 se- quences from the novel species were 72%-77% similar to those of Varestrongylus alpenae(Dikmans, 1935) and 51%- 61% similar to those of other protostrongylids known in North American and some Eurasian ungulates. Results indicate a discrete lineage of an undescribed protostrongylid infecting muskoxen, caribou, and moose from Alaska to Labrador. Sym- patric infections with Parelaphostrongylus andersoniPrestwood, 1972 were found in three caribou herds.