| Abstract: | A new genus and species of the formerly monobasic and predominantly amphitropical, ichneumonid subfamily, Eucerotinae, is described from Chile. A phylogenetic analysis of the redefined Eucerotinae is undertaken. Barronia araucaria gen. et sp. n. has a sister-group relationship with Euceros. The southern hemisphere species of the latter genus were found to comprise a monophyletic clade, the sister group to all other Euceros species. Similarly all north temperate Euceros species form a monophyletic clade, the sister group of which occurs in Madagascar. Within the former clade, the North American species form a monophyletic group, the sister species of which is Palaearctic. Several other groups of Palaearctic taxa have a sister-group relationship to this lineage. These results suggest the Eucerotinae had an ancient origin on Gondwanaland in the lower Cretaceous, prior to the separation of the Indo-Madagascar terrane from the Australian-Antarctic-South American tectonic plate. We hypothesize the Palaearctic fauna colonized Eurasia following the impaction of India on to its southern margin, and that the North American fauna is derived from a single circum-polar dispersal from Eurasia. Our results do not support an earlier hypothesis that the Eucerotinae arose as hyperparasitoids of Symphyta. Evidence suggests the group arose as parasitoids of ophioniform ichneumonids attacking lepidopterous larvae feeding on gymnosperms or anemophilous angiosperm trees. |
