The extraordinary diversity of herbivorous beetles is usually attributed to coevolution with angiosperms. However, the degree and nature of contemporaneity in beetle and angiosperm diversification remain unclear. Here we present a large-scale molecular phylogeny for weevils (herbivorous beetles in the superfamily Curculionoidea), one of the most diverse lineages of insects, based on approximate to 8 kilobases of DNA sequence data from a worldwide sample including all families and subfamilies. Estimated divergence times derived from the combined molecular and fossil data indicate diversification into most families occurred on gymnosperms in the Jurassic, beginning approximate to 166 Ma. Subsequent colonization of early crown-group angiosperms occurred during the Early Cretaceous, but this alone evidently did not lead to an immediate and major diversification event in weevils. Comparative trends in weevil diversification and angiosperm dominance reveal that massive diversification began in the mid-Cretaceous (ca. 112.0 to 93.5 Ma), when angiosperms first rose to widespread floristic dominance. These and other evidence suggest a deep and complex history of coevolution between weevils and angiosperms, including codiversification, resource tracking, and sequential evolution.
Thoracic structures of Tetraphalerus bruchi are described in detail. The results were compared with features found in other representatives of Archostemata and other coleopteran suborders. Differences between thoracic structures of Tetraphalerus and members of other archostematan subgroups are discussed. External and internal characters of larval and adult representatives of 37 genera of the coleopteran suborders are outlined, coded and analysed cladistically, with four groups of Neuropterida as outgroup taxa. The results strongly suggest the branching pattern Archostemata + [Adephaga + (Myxophaga + Polyphaga)]. Coleoptera excluding Archostemata are supported with a high Bremer support. Important evolutionary changes linked with this branching event are simplifications of the thoracic skeleton resulting in reduced degrees of freedom (i.e. a restricted movability, especially at the leg bases), and a distinct simplification of the muscle system. This development culminates in Polyphaga, which are also strongly supported as a clade. Internalization of the partly reduced propleura, further muscle losses, and the fusion of the mesoventrites and metaventrites-with reversal in Scirtoidea and Derodontidae-are autapomorphies of Polyphaga. Archostemata is a small relict group in contrast to highly successful xylobiontic groups of Polyphaga. The less efficient thoracic locomotor apparatus, the lack of cryptonephric Malpighian tubules, and the rise of angiosperms with beetle groups primarily adjusted to them may have contributed to the decline of Archostemata.(C) The Willi Hennig Society 2008.