Abstract
Descriptions illustrated with 102 line drawings are provided for 31 new North American genera and 44 new species of Pteromalidae, and for 2 species of Tetracampidae (Hymenoptera, Chalcidoidea). They are published in order to provide names for these taxa mentioned in the keys to genera of the Nearctic Chalcidoidea. In Pteromalidae the genera described as new include Conigastrus, Arriva, Huberina, Ottawita, Nadelaia, Ptinocida, Duartea, Grissellium, Kukua, Meximalus, Dineuticida, Lenka, Bonitoa, Propodeia, Alticornis, Kratka, Abomalus, Jaliscoa, Euteloida, Mazinawa, Oaxa, Raspela, Hlavka, Kazina, Babina, Yosemitea, Miristhma, Vespita, Andersena, Laesthiola and Lasallea. In 10 other genera mostly known before only from outside of North America, the first Nearctic species are described, in other genera new transfers or new synonymies are proposed or species are redescribed or commented on. In Andersena a new species is described by Mr H. Andersen. In Tetracampidae one species is described in Platynocheilus and another in Epiclerus, and the known species of Platynocheilus are keyed out including a European species which had to be given a new name.