Skrjabingylus chitwoodorum Hill, 1939 (Nematoda: Metastrongyloidea) in Striped Skunks from Northcentral Minnesota

Received for publication 25 April 1984. ments overlapped (Fig. 1). The maximum length of P. boughtoni (range = 380-500 m) fell below the range of larvae of Pnotostrongylus spp. from bighorn sheep (527-673 jim), but overlapped with that of 0. inacnotis (488-611 tm). Also, maximum length of 0. macnotis overlapped with the range of Pnotostnongylus spp. from bighorns. Therefore, where the three definitive hosts are sympatric, only infective larvae in the extremes of the total length range for all species can be identified with confidence. Larvae of P. boughtoni can be distinguished from those of Pnotostnongylus spp. from bighorns if there is no possibility of Onthostnongylus larvae occurring in a sample. Although total length is not the most consistent morphologic basis on which to separate species of helminths, such a method is attractive in its simplicity and adaptability to field studies. Third-stage larvae of some species in the confamiliar genus Panelaphostnongylus differ in tail structure (Ballantyne and Samuel, 1984, J. Parasitol. In press). Specific structural differences may be found among Pnotostnongylus and Onthostnongylus infective larvae, but rapid examination of fine morphological details is prevented by the nearly opaque first-stage cuticle. Removal of this cuticle without damaging the larva inside, though not impossible, is extremely difficult and time-consuming. We wish to thank Brent Gray and Judith Samson for assistance in exposing and maintaining snails. This study was supported by the Alberta Fish and Wildlife Division, and the Natural Sciences and Engineering Research Council of Canada.