This work is a taxonomic revision of two large subfamilies of Ichneumonidae present in Costa Rica, the Metopiinae and Banchinae. The study is based on an intensive biological inventory, and in total more than 10,000 specimens have been examined, although not all have been mounted and labelled. Such collecting is essential as it ensures the very large number of rare species present in tropical habitats are adequately represented. Biologically, the two ichneumonid subfamilies treated in this work are similar in that the majority of species are koinobiont endoparasitioids of the larvae of weakly concealed Lepidoptera, whilst a few taxa in each subfamily are specialized to attack exposed caterpillars. The study has revealed the presence in Costa Rica of 14 genera and 130 species of the ichneumonid subfamily Metopiinae, and 24 genera and 253 species ofthe subfamily Banchinae. Illustrated keys are given to enable all of these taxa to be identiﬁed by the non-specialist.
In the Metopiinae 124 new species and one new genus, Forrestopius, are described. The other metopiine taxa (13 genera and 6 species), which have previously been named, are re-described in a standardised format. In the Banchinae extensive re-definition of the Neotropical atrophine genera has been undertaken, and six new genera have been described: Cordeleboea, Hadeleboea, Hylesicida, Podeleboea, Quillonota and Wahlamia. One Old World genus, Leptobatopsis, is recorded from the New World for the ﬁrst time, and two South American genera, Cecidopimpla and Ptychopsis, are newly recorded for Central America. Eudeleboea is treated as a synonym of Meniscomorpha (syn. n.) and Isomeris is placed in synonymy under Lissonota (syn. n.). Deleboea is restricted to include only the Andean type-species. In the Banchinae 237 new species are described and the 16 species, which have previously been named, are re-described in a standardised format. Meniscus crassitarsus Cresson is placed in Hylesicida (comb n.), Lissonota pulchra Cameron is shown to be a junior synonym of Mnioes jucundus (Cresson) (syn. n.), Mesoleius zapotecus Cameron is a junior synonym of Extastes tarsalis Cresson (syn. n.) and Phytodietus guatemalensis Cameron is a junior synonym of Loxodocus cressoni (Cameron) (syn. n.). Where known, details are presented about the geographical distribution, seasonal abundance and recorded hosts of all the various taxa. An appendix provides a supplement to the treatment of the Pimplinae given in Volume 1 of this series (Memoirs of the American Entomological Institute, Volume 47). In this a new genus and species, lnbioia pivai, are described. Full nomenclatural details are listed in Appendix 2.