Cuticular ridge patterns of Nematodirella (Nematoda: Trichostrongyloidea) of North American ruminants, with a key to species

Abstract

Trichostrongyloid nematodes are usually identifed by characteristics of the males. In an effort to find additional diagnostic characteristics of both sexes of Nematodirella of North American ruminants, cuticular ridges were studied. Four distinct cuticular morphotypes were found among specimens from North American ruminants. The four cuticular morphotypes represent three species previously reported in North America and a fourth Asian species not previously reported in North America. One species has numerous ridges that are discontinuous in a regular pattern: N. antilocaprae, parasitic in the pronghorn antelope, Antilocaprae americana, is believed to be confined to North America. Two species have numerous continuous ridges and are parasites of Holarctic cervids, namely, N. longissimespiculata with 44–52 cervical ridges, parasitic in the reindeer, Rangifer tarandus, and N. alcidis with 28–34 cervical ridges, parasitic in the moose, Alces alces. The fourth species, N. gazelli, has 14 cervical ridges, and is parasitic in Holarctic bovids including Ovis aries. A fifth species, not known to occur in North America, was also studied — N. dromedarii with 22 cervical ridges is parasitic in the camel, Camelus dromedarius. The cuticular characteristics are correlated with other characteristics in a key to species and the evolution of the species of Nematodirella is discussed. Numerous redeterminations are made of specimens from earlier reports. ac]19821013