Litomosoides pardinasi n. sp. (Nematoda, Onchocercidae) from two species of cricetid rodents in northern Patagonia, Argentina.

Seventy-seven cricetid rodents, corresponding to six different species, deposited at the Mammal Collection at Centro Nacional Patagónico, Puerto Madryn, Chubut, were examined for parasites. Litomosoides pardinasi n. sp. is described parasitizing the pleural and abdominal cavities of Phyllotis xanthopygus (Phyllotini) and the abdominal cavity of Oligoryzomys longicaudatus (Oryzomynii) in the northern Patagonia, Argentina. The new species is included in the carinii group, characterized by the presence of a right spicule with a dorsal heel and a terminal cap well cuticularized; left spicule composed with a handle longer or as long as the blade, and the blade constituted by a cuticularized distal filament. Litomosoides pardinasi n. sp. possesses a buccal capsule tubular with an anterior enlargement, and a smooth cavity; four labial and two dorsal cephalic papillae; vulva posterior to the esophagus-intestinal junction; male tail with three to five pairs of symmetric postcloacal papillae; female tail slender; vagina globular and small. This is the first record for a filarioid in a Phyllotini rodent and the southernmost record of any filarioid species worldwide.