Abstract
The genus Priotomis (Townes, 1969, p. 292) was placed by its author in the subtribe Lymeonina of the ichneumonid tribe Mesostenini. While data provided by a study of the new species treated in this article do not controvert that placement it is well to emphasize that Priotomis shows a number of singularly aberrant characters unparalleled among other genera of its subtribe. For example, the presence of a series of teeth on the dorsal valve of the ovipositor tip recalls the Baryceratina rather than the Lymeonina, whereas the specialized, twisted mandibular apex is not found in any other mesostenine genus.Priotomis was described from a unique female collected in the wet subtropical forest of Santa Catarina State in southern Brasil. Now, however, another specimen has come to light, from the invernally deciduous Chaco Forest o northwest Argentina, and this form, while agreeing perfectly with Townes' diagnosis of Priotoms, differs in so many respects from its Brazilian congener that it must be recognized as a separate species.