Abstract.  1. The parasitic wasp family Ichneumonidae (Hymenoptera) is of great interest because it has been claimed that its species richness does not increase with decreasing latitude. 2. No extensive studies of the family have been conducted in South American localities. 3. Arthropods were sampled using 27 Malaise traps in the Allpahuayo–Mishana National Reserve (56 000 ha) in the north‐eastern Peruvian Amazonian lowland rainforest. The total duration of the sampling programme was 185 Malaise trap months. 4. Altogether, 88 species were collected. This is one of the highest local pimpline and rhyssine species numbers ever recorded. A comparison with results from Mesoamerica revealed that at equal numbers of individuals sampled, the number of Pimplinae and Rhyssinae species in Peruvian Amazonia is at least twofold compared with lowland locations in Mesoamerica and somewhat higher than in the most species‐rich Costa Rican higher altitude localities. 5. Non‐parametric methods of estimating species richness were applied. These suggest that additional sampling would yield a considerable number of new Pimplinae and/or Rhyssinae species.

The enormous cytochrome oxidase subunit I (COI) sequence database being assembled from the various DNA barcoding projects as well as from independent phylogenetic studies constitutes an almost unprecedented amount of data for molecular systematics, in addition to its role in species identification and discovery. As part of a study of the potential of this gene fragment to improve the accuracy of phylogenetic reconstructions, and in particular, exploring the effects of dense taxon sampling, we have assembled a data set for the hyperdiverse, cosmopolitan parasitic wasp superfamily Ichneumonoidea, including the release of 1793 unpublished sequences. Of approximately 84 currently recognized Ichneumonoidea subfamilies, 2500 genera and 41,000 described species, barcoding 5'-COI data were assembled for 4168 putative species-level terminals (many undescribed), representing 671 genera and all but ten of the currently recognized subfamilies. After the removal of identical and near-identical sequences, the 4174 initial sequences were reduced to 3278. We show that when subjected to phylogenetic analysis using both maximum likelihood and parsimony, there is a broad correlation between taxonomic congruence and number of included sequences. We additionally present a new measure of taxonomic congruence based upon the Simpson diversity index, the Simpson dominance index, which gives greater weight to morphologically recognized taxonomic groups (subfamilies) recovered with most representatives in one or a few contiguous groups or subclusters.

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Utilising short‐term but geographically extensive sampling in Guatemala, Honduras, and Nicaragua, we examined altitudinal trends in species richness and diversity of ichneumonid parasitoid wasps. This study covered 19 subfamilies, including four globally large subfamilies that have not yet been taxonomically revised in the Neotropics. Sampling was done at 25 sites classified into three elevational categories on the basis of the average elevation of traps at each site (low 34–659 m a.s.l., middle 1033–1709 m a.s.l., and high 1930–2565 m a.s.l.). A total of 2847 ichneumonid individuals were captured and sorted into 751 morphospecies, most of which were identified to the genus level. We found a clear compositional gradient in ichneumonid communities along the elevational gradient, as the majority of species were restricted to either one elevational zone or two adjacent zones. In our data, mid‐ and high‐elevation sites had generally higher ichneumonid species richness and diversity than low‐elevation sites. These trends were largely similar to those found in larger scale Mesoamerican ichneumonid studies. Yet, the low ichneumonid richness at low elevations may partly be a sampling artefact. This provides a new piece of evidence for the suggestion that extensive sampling is needed for uncovering the real diversity of ichneumonids in tropical lowland forests, and that the reputation of Ichneumonidae as a notable example of a reversed latitudinal diversity gradient may be undeserved.

More faunistic and taxonomic information about the species of the genus Atractodes of the Palaearctic Region are reported. The following species are described as new: A. cylindraceus sp. n., A. foveoclypeatus sp. n., A. kasparyani sp. n., A. magnus sp. n. and A. rossicus sp. n. The females of A. procerus Foerster and A. remotus Jussila, and the male of A. turkuensis Jussila are described. A. ficticius (Foerster) is a senior synonym of A. genuinus Foerster, and A. helveticus (Foerster) a senior secondary homonym of A. helveticus Foerster and a senior synonym of A. oreophilus Foerster. A. areolaris (Habermehl) is a new junior synonym of A. gravidus Gravenhorst and A. cinctus (Foerster) a junior synonym of A. fumatus (Haliday). A. remotus Jussila is given a species rank. New combinations are A. cinctus (Foerster) and A. helveticus (Foerster). Renewed keys to the females and males of western Palaearctic Atractodes have been made.