Cladistics of the Tryphoninae (Hymenoptera: Ichneumonidae) with a discussion of host use and the evolution of parasitism in the Ichneumonidae

A cladistic revision of the world genera of the Tryphoninae (Hymenoptera: Ichneumonidae) was performed using morphological and life history characters from adult, egg and larval stages. Previous studies recognized eight tribes and 52 extant genera. The present study classified the Tryphoninae into seven tribes and 55 genera. Exenterini syn.n. was synonymized with Tryphonini because Exenterini syn.n. rendered Tryphonini paraphyletic. The Idiogrammatini were sister taxon of all other tryphonines.; Two new genera were recognized (to be described in subsequent publications). In addition, Otoblastus was divided into Otoblastus s.s. and Cerda gen.reinst. Cteniscus (Japanicola) was raised to generic status forming Japanicola stat.n. Cosmoconus (Otitoconus) was moved to Tryphon as a subgenus. Brevitubulus aequilatus syn.n. was synonymized with Netelia (Bessobates). Eclytus (Zapedias) was re-synonymized with E. (Eclytus). Cosmoconus ( Alpicosmus) syn.n. was synonymized with C. (Cosmoconus). The fossil Eubaeus leiponeura was removed to the Neorhacodinae. Tribal and generic keys and descriptions are provided for adults. The final larval instar of Acrotomus and Orthomiscus are described for the first time.; The preferred cladogram was used to examine hypotheses regarding evolution of host use in tryphonines. Evidence supported the hypothesis that koinobiosis arose from idiobiosis and that lepidopteran parasitism arose from hymenopteran parasitism. Furthermore, the ancestral trypbonine most likely parasitized concealed hosts because this is the predominant host type in outgroup taxa and the ancestor of all tryphonines other than the Idiogrammatini switched directly from parasitizing concealed hosts to exposed hosts, contrary to the predicted transformation: concealed to semi-concealed to exposed hosts.; The preferred cladogram was also used to predict host ranges. The hypothesis that Ankylophon parasitizes hymenopterans was not upheld by the phylogenetic analysis because Ankylophon was resolved in a lepidopteran-parasitizing clade. Finally, the phylogeny was used to investigate why Netelia is so speciose. A switch to parasitizing exposed hosts or a switch to lepidopteran parasitism cannot be used to explain the species richness of Netelia because these traits evolved earlier than in the ancestor of Netelia. A switch to nocturnal behaviour correlates with an increase in species richness of Netelia ; however, an increase in species richness is not evident in other nocturnal tryphonines.