Abstract
Heligmosomoides crarigi n. sp. (Nematoda: Heligmosomoidea) is described from Microtus limnophilus Buchner, 1889 (Rodentia: Cricetidae) from Rangtang, Sichuan, China. It is related to H. protobullosus Asakawa, 1987 and H. longispiculum Tokobaev & Erkulov, 1966 both parasites of Microtus spp. from Japan and USSR, respectively by the following features: a ratio of spicule length/body length of more than 45 % and rays 9 shorter than rays 10. The new species is differentiated by rays 8 being closed to rays 6 and 19-22 cuticular ridges versus 14 in H. protobul10sus (synlophe not described in H. longispiculum). H. longicirratus (Schulz, 1954) also a parasite of Microlus sp. from the USSR is the most closely related species based on the number of cuticular ridges (20) and the ratio of spicule length/body length (48 % versus 50 %). There are no illustrations of this species and the female has not been described; for that reason, it is not possible to compare it accurately with our specimens.