The life cycle of Ohbayashinema erbaevae (Nematoda, Heligmosomoidea, Heligmosomidae) in Ochotona rufescens rufescens (Ochotonidae).

The morphogenesis and the chronology of the life cycle of Ohbayashinema erbaevoe Durette-Desset et al, 2000, a parasite of Ochotona daurica from Buriatia were studied in detail in an experimental host, Ochotona rufescens rufescens. Worm-free pikas were each infected per os with O. erbaevae larvae and were killed at one day post infection (DPI 1) and every 12 hours from 1.5 to 8 days post infection. By DPI 1, all the larvae were exsheathed and in the small intestine. The third moult occurred in 2.5-3.0 days. The last moult occurred in 4.0-4.5 days. The prepatent period was eight days and the patent period lasted between two and 12 weeks. The distribution of O. erbaevae along the small intestine of the pikas was assessed. For each experiment, a morphological description of the different stages of the life cycle was provided. The morphogenesis and the chronology of the life cycle of O. erbaevae appear to be identical with those of two other genera of the family of the Heligmosomidae, Heligmosomum Railliet & Henry, 1909 and Heligmosomoides Hall, 1916. They confirm that the three genera belong to the same family. The presence of an abortive posterior genital branch in the female of O. erbaevae, which represents the posterior part of the genital primordium of the didelphic females, supports the systematic position of the genus Ohbayashinema between the didelphic genus Citellinema Hall, 1916 and the monodelphic genera Heligmosomum and Heligmosomoides.