Vertical transmission of a nematode from female lizards to the brains of their offspring. Novel nematodes in lizards

Vertebrates are hosts for a diverse range of nematodes. Transmission of nematodes is often trophic and involves a change in host species , but some species that parasitize mammals have evolved vertical transmission within a single host species, either through the milk or by crossing the placenta. While the intimate connection between mother and young in mammals is conducive to transplacental and transmammary transmission routes, vertical transmission may be constrained in egg-laying amniotes. However, here we report the first incidence of transovarial transmission of a previously undescribed nematode in the common wall lizard, Podarcis muralis. Our video documentation shows that nematodes enter the brain early in embryonic development. Invested lizard embryos develop normally and hatch with nematodes residing in their braincase. We present a morphological and molecular phylogenetic characterization of the new nematode that suggests that it is a representative of a previously unknown taxonomic group.