[A new classification of Trichostrongyloidea nematodes (author's transl)].

The preliminary classification that we proposed in 1977 grouped provisionally in the family Amidostomatidae all the primitive Trichostrongyloidea (with the exception of the Strongylacanthidae). The study of several nematodes from reptiles and amphibians, and above all parasites of Australian monotremes and marsupials, lead us to split up this family. We believe that two families, Amidostomatidae and Strongylacanthidae evolved from ancestors close to the Ancylostomatoïdea. All the others, however, appear to have evolved from the Strongyloïdea. The morphological characters considered permit the elucidation of three principal evolutionary lines, recognized for the primitive forms by the anatomy of the caudal bursa and for specialized forms by the structure of the synlophe. The principal evolution of the group seems to have occurred during the Secondary Era in Gondwanaland. The families and sub-families remain very numerous in the Neotropical and Australian zones.