A new species of Heligmosomoides Hall, 1916 is proposed for nematodes collected from Peromyscus maniculatus (Wagner) in western Canada. The diagnostic trait for this species is the presence of 2 ventral bulbs on the bursal membrane. Only 3 species, Heligmosomoides bullosus, Heligmosomoides vandegrifti, and Heligmosomoides douglasi, are characterized as possessing a bursal membrane. However, the bursal membrane of the specimens herein described feature 2 parts that resemble calluses or bobbles, whereas there is only 1 in Heligmosomoides vandegrifti, Heligmosomoides bullosus, and Heligmosomoides douglasi. Further, the new species can be differentiated by the size of spicules 759–892 μm, which are longer than those in Heligmosomoides vandegrifti 635–740 μm, yet smaller than those of Heligmosomoides douglasi, which are 1 mm. The genetic distance between Heligmosomoides bibullosus sp. nov, and its putative sister clade Heligmosomoides vandegrifti is congruent with their geographical separation of 4,000km. Finally, this study suggests the monophyly of Heligmosomoides in North America, which includes worms infecting species of the Cricetidae, Geomyidae, Arvicolidae, and Muridae.
Nematoda, Heligmosomoides, Heligmosomoides bibullosus, Peromyscus maniculatus, Heligmosomoidea, Museum Research, Yukon Territory, British Columbia