The Labeninae (Hymenoptera : Ichneumonidae): a study in phylogenetic reconstruction and evolutionary biology

The internal phylogenetic relationships of the ichneumonid subfamily Labeni nae (Hymenoptera) are re-assessed using 136 characters for 54 species repre senting all currently known species-groups. New character sets are used. Th ese include a new form of sera (named the grosssulariform setae) which are present on the inner surface of the hind coxa of some females, and the exte nsive structural modifications of the terminal segments of the female metas oma, which are described and structural homologies established. The monophy ly of the Labeninae and of the four component tribes, Groteini, Poecilocryp tini, Xenothyrini and Lahenini, is demonstrated The Groteini is shown to be the sister-group to the Poecilocryptini + (Xenothyrini + Labenini). Monoph yletic genera are established, including three new genera: Ozlabium gen. no v. Gauld & Wahl(type-species O. arcadium sp. nov.) in the Groteini from Aus tralia; Torquinsa gen. nov. Gauld & Wahl (type-species Certonotus invictus Porter) in the Labenini from Chile, and Gauldianus gen. nov. Lanfranco (typ e-species Gauldianus chilensis sp. nov. Lanfranco) in the Labenini from Chi le. Apechoneura is removed from synonymy and re-instated as a valid genus f or a complex of tropical American species. The biogeographic patterns shown by the Labeninae are discussed. Evidence suggests that the group radiated on Gondwanaland after the separation of,Africa/India/Madagascar, bur prior to the separation of Australia. Species occurring off the southern continen tal fragments, in North America, are shown to be members of highly derived lineages, a result consistent with the hypothesis that labenines colonized North America recently through Mesoamerica. Patterns of host utilization an d mating behaviour are examined for the group. Members of the more defined lineages show- progressively more female specializations for attacking host s deeply concealed in woody substrates, Males in the more specialized linea ges are shown to have a wider array of secondary sexual characteristics and genitalic ornamentations than more plesiomorphic taxa. (C) 2000 The Linnea n Society of London.