Morphological and molecular identification of Habronema spp. (Nematoda: Habronematidae) from donkeys in Xinjiang, China, and notes on the taxonomical status of Habronema majus (Creplin, 1849) and H. microstoma (Schneider, 1866).

Habronematid nematodes were collected from the stomachs of donkeys, Equus asinus L., in the Tarim Basin, Xinjiang, China. After examination by light and scanning electron microscopy, Habronema muscae (Carter, 1861) and H. majus (Creplin, 1849) were identified. The morphology of our specimens representing H. muscae (Carter, 1861) agreed well with previous redescriptions in the shape of the lateral lips, origin of the lateral alae, ratio of left and right spicules, and number and arrangement of caudal papillae. However, H. majus (Creplin, 1849) differs from H. microstoma (Schneider, 1866) in the arrangement of the caudal papillae in the male. Moreover, molecular analysis also showed interspecific differences of 26.2-28.2% in ITS2 and 8.6-8.9% in cox1 between H. majus and H. microstoma, a divergence much higher than the known intraspecific variation of Habronema spp. (6.6-8.7% in ITS2; 0.2-2.2% in cox1). The results indicate that both H. microstoma (Schneider, 1866) and H. majus (Creplin, 1849) are valid species.