Hassalstrongylus dollfusi

Hassalstrongylus dollfusi is a medium-sized nematode (3-10 mm in length), generally uncoiled, sometimes loosely coiled in 1–3 spirals.^[1]{^[3]}

According to Serrano et al. (2021), characters of Hassalstrongylus dollfusi males are: the morphology of the caudal bursa and the peculiar shape of the distal tip of the spicules. Characters of the female are: the dorsal cuticular inflation at ovejector level and the subventral postvulvar alae supported by hypertrophied struts.^[3]

The species is parasitic in the small intestine of rodents. Hassalstrongylus dollfusi was first described in 1963^[1] as a parasite of a wild house mouse, Mus musculus, in Venezuela and was never reported again for the next six decades. In 2021 a paper based on a large survey of native rodents showed that the species was actually present as a parasite in five species of wild native cricetid rodents in Argentina: Oligoryzomys fornesi, Oligoryzomys flavescens, Oligoryzomys nigripes, Holochilus chacarius and Akodon azarae.^[3] The authors wrote that Hassalstrongylus dollfusi showed a strong preference for host species of Oligoryzomys, which appear to act as primary hosts.^[3]