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

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Abstract
The internal phylogenetic relationships of the ichneumonid subfamily Labeninae (Hymenoptera) are re-assessed using 136 characters for 54 species representing all currently known species-groups. New character sets are used. These 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 extensive structural modifications of the terminal segments of the female metasoma, which are described and structural homologies established. The monophyly of the Labeninae and of the four component tribes, Groteini, Poecilocryptini, Xenothyrini and Lahenini, is demonstrated The Groteini is shown to be the sister-group to the Poecilocryptini + (Xenothyrini + Labenini). Monophyletic genera are established, including three new genera: Ozlabium gen. nov. Gauld & Wahl(type-species O. arcadium sp. nov.) in the Groteini from Australia; Torquinsa gen. nov. Gauld & Wahl (type-species Certonotus invictus Porter) in the Labenini from Chile, and Gauldianus gen. nov. Lanfranco (type-species Gauldianus chilensis sp. nov. Lanfranco) in the Labenini from Chile. Apechoneura is removed from synonymy and re-instated as a valid genus for 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 continental 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 and mating behaviour are examined for the group. Members of the more defined lineages show- progressively more female specializations for attacking hosts deeply concealed in woody substrates, Males in the more specialized lineages are shown to have a wider array of secondary sexual characteristics and genitalic ornamentations than more plesiomorphic taxa. (C) 2000 The Linnean Society of London.