Phylogeny of the Hymenoptera: A cladistic reanalysis of Rasnitsyn's (1988)data

The hypothesis of higher-level relationships among extinct and extant hymen opterans presented by Rasnitsyn in 1988 is widely cited but the evidence ha s never been presented in the form of a character matric. or analysed cladi stically. We review Rasnitsyn's morphological work and derive a character m atrix for fossil and recent hymenopterans from it. Parsimony analyses of th is matrix under equal weights and implied weights show that there is little support for Rasnitsyn's biphyletic hypothesis, postulating a sister-group relationship between tenthredinoids and macroxyelines. instead, the data fa vour the conventional view that Hymenoptera excluding the Xyelidae are mono phyletic. Higher-level symphytan relationships are well resolved and, excep t for the basal branchings, largely agree with the tree presented by Rasnit syn. There is little convincing support for any major divisions of the Apoc rita but the Microhymenoptera and the Ichneumonoidea + Aculeata appear as m onophyletic groups in some analyses and require only a few extra steps in t he others. The Evaniomorpha appear as a paraphyletic grade of basal apocrit an lineages and enforcing monophyly of this grouping requires a considerabl e increase in tree length. The Ceraphronoidea are placed in the Proctotrupo morpha, close to Chalcidoidea and Platygastroidea. This signal is not entir ely due to loss characters that may have evolved independently in these tax a:in response to a general reduction in size. The analyses suggest that the Proctotrupomorpha may be monophyletic if the ceraphronoids are included. T he Chrysidoidea are resolved in good agreement with relationships proposed by Brothers and Carpenter in 1993 but in conflict with the tree presented b y Rasnitsyn. Rasnitsyn's data are largely uninformative about relationships among the Aculeata sensu stricto. The results are compared with those of o ther recent analyses of higher-level hymenopteran relationships.