| The subfamily Macrocentrinae (Hymenoptera: Ichneumonoidea: Braconidae) comprises koinobiont endoparasitoids that usually attack concealed lepidopterous larvae feeding within roots, stems, cases, leaves tied together, or rolled leaves. Some species attack exposed lepidopterous and hymenopterous (sawfly) larvae. In the Western Hemisphere the subfamily occurs from northern Canada and Alaska southward to Argentina. This treatment, however, is limited to those of America north of Mexico. All species are illustrated and described with geographic distribution and host information.; Five Nearctic macrocentrine genera (one new) are here recognized. Austrozele Roman, 1910, includes two valid Nearctic species. Dolichozele Viereck, 1911, includes three valid Nearctic species (two new). Hymenochaonia Dalla Torre, 1898, includes six valid Nearctic species (two new). Macrocentrus Curtis, 1833, includes 44 valid Nearctic species (seven new) plus one possible new species informally described here based only on males. The new genus includes only a single species (new) with highly unusual foliaceous hind tibiae.; Five species are moved from Macrocentrus to new combinations: Austrozele soror (Mason), A. uniformis (Provancher), Hymenochaonia diorytriae (Muesebeck), H. nupera (Cresson), H. texana (Muesebeck); M. crambivorus Viereck, 1911, is placed as a junior synonym of M. crambi (Ashmead, 1894). A total of 7,153 specimens were examined (4,318 females and 2,835 males).; Keys to the macrocentrine genera and species and a preliminary analysis of the phylogenetic relationships among the genera are provided. The analysis (based on seven genera and the outgroup Orgilus coded for 15 binary characters) suggests that Macrocentrus may be paraphyletic with respect to the other macrocentrine genera.; The work includes 470 figures (photographs, scanning electron micrographs and line drawings) that depict the features of the head, antennae, wings, mesosoma, and metasoma, for each species. |
