Spirocerca vulpis sp. nov. (Spiruridae: Spirocercidae): description of a new nematode species of the red fox, Vulpes vulpes (Carnivora: Canidae)

Previous studies have reported nematodes of the Spirocercidae family in the stomach nodules of red foxes (Vulpes vulpes) described as Spirocerca sp. or Spirocerca lupi (Rudolphi, 1819). We characterized spirurid worms collected from red foxes and compared them to S. lupi from domestic dogs by morphometric and phylogenetic analyses. Nematodes from red foxes differed from S. lupi by the presence of six triangular teeth-like buccal capsule structures, which are absent in the latter. Additionally, in female worms from red foxes, the distance of the vulva opening to the anterior end and the ratio of the glandular-to-muscular oesophagus lengths were larger than those of S. lupi (P < 0.006). In males, the lengths of the whole oesophagus and glandular part, the ratio of the glandular-to-muscular oesophagus and the comparison of the oesophagus to the total body length were smaller in S. lupi (all P < 0.044). Phylogenetic analyses revealed that S. lupi and the red foxes spirurid represent monophyletic sister groups with pairwise nucleotide distances of 9.2 and 0.2% in the cytochrome oxidase 1 and 18S genes, respectively. Based on these comparisons, the nematodes from red foxes were considered to belong to a separate species, for which the name Spirocerca vulpis sp. nov. is proposed.