UMINGMAKSTRONGYLUS-PALLIKUUKENSIS GEN-NOV ET SP-NOV (NEMATODA, PROTOSTRONGYLIDAE) FROM MUSKOXEN, OVIBOS-MOSCHATUS, IN THE CENTRAL CANADIAN ARCTIC, WITH COMMENTS ON BIOLOGY AND BIOGEOGRAPHY

Umingmakstrongylus pallikuukensis gen.nov. et sp.nov. is established f or a protostrongylid nematode in muskoxen, Ovibos moschatus, from the Kitikmeot Region (central Arctic) of the Northwest Territories, Canada . It is distinguished from Cystacaulus and other Muelleriinae by chara cters that include the following: males: deeply incised, bilobed bursa , independent externodorsal rays, telamon composed of distal transvers e plate, absence of falcate crurae, and spicules not distally split; f emales: absence of provagina; and first-stage larvae: presence of thre e cuticular folds on the tail. The great length of females (468 mm) an d males (171 mm) is exceptional among the Protostrongylidae. Pathognom onic lesions include well-defined cysts dispersed through the lung tis sue (maximum diameter 40 mm) containing adult and larval parasites in a dense matrix. Transmission involves a molluscan intermediate host, a s indicated by experimental infections in the slug Deroceras reticulat um. The parasite is apparently restricted in its geographic distributi on and has been found only in a population of muskoxen northwest of Co ppermine, N.W.T. This may be indicative of a relictual host-parasite a ssemblage that has existed since the Pleistocene. The pathogenicity, h igh prevalence, and intensity of infection in the Coppermine herd sugg est that the occurrence of U. pallikuukensis has implications for the management of muskoxen in the Holarctic region.