'First record of(Nematoda: Strongylidae) in North America: Morphological and molecular identification of a rare equine strongyle.

Abstract

Equids are infected by a diversity of gastrointestinal nematode parasites, including 64 species of equine strongyle nematodes from19 genera. Despite numerous surveys of horse strongyles worldwide, certain geographic regions and rare species remain understudied. In 1964, a new species of equine strongyle,, was described from a donkey in China. Subsequently, this species was recorded in horses from Kazakhstan and reclassified as(K'ung and Yang, 1964), the only species in this genus. Since then,has not been reported elsewhere, with limited knowledge on its distribution and phylogeny.This study documents the first record ofin North America. Adult specimens were recovered from fecal samples of a domestic horse in Alberta, Canada, following treatment with ivermectin. Species identification involved detailed morphological examination, complemented with sequencing of the internal transcribed spacer 1 (ITS1), 5.8S rRNA gene, and the internal transcribed spacer 2 (ITS2) regions of the nuclear genome. Phylogenetic analysis indicated a close evolutionary relationship with species fromandgenera. Nemabiome ITS2 sequencing of a paired pre-treatment sample also detected the presence ofin the studied horse. Re-analysis of public equine nemabiome datasets further detectedin feral horses in Alberta, but not in other regions considered. This study expands the known distribution of this rare species and enhances our knowledge of its placement in the phylogeny of equine strongyles. Furthermore, our re-analysis of public nemabiome datasets highlights the value of this approach for studying the global distribution of parasite species.