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R. Beutel et al.: On the head morphology of Tetraphalerus, the phylogeny of Archostemata and the basal branching events in Coleoptera

Rolf G. Beutel, Si-qin Ge, Thomas Hoernschemeyer
On the head morphology of Tetraphalerus, the phylogeny of Archostemata and the basal branching events in Coleoptera.
Cladistics, 23 (2007): 1-29.

(Institut fuer spezielle Zoologie und Evolutionsbiologie, FSU Jena, 07743, Germany;
Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China;
Institut fuer Zoologie & Anthropologie, Abteilung Morphologie & Systematik, Georg-August-Universitaet, 37073, Goettingen, Germany)

Accepted 10 July 2007


Internal and external features of Tetraphalerus bruchi were studied using X-ray microtomography (l-CT) and other techniques, and head structures were described in detail. l-Ct is highly efficient for the assessment of anatomical data. A data matrix with 90 morphological characters of recent and fossil beetles was analyzed with different approaches (parsimony, Bayesian analysis).
The results of the parsimony analysis resulted in the following branching pattern: (Tshekardocoleidae + (Permocupedidae, Rhombocoleidae + (Triadocupedidae + ((Adephaga + (Myxophaga + Polyphaga)) ) + Archostemata s.str. [including Jurodidae]))).
Sikhotealinia is placed as sister group of Jurodes (Jurodidae), and Jurodidae as sister group of the remaining Archostemata (Bayesian analysis) or of a clade comprising Micromalthidae, Crowsoniellidae, Ademosynidae, Schizophoridae and Catiniidae. The monophyly of Ommatidae and Cupedidae is well supported and Priacma is placed as the sister group of all other Cupedidae. Important events in the early evolution of Coleoptera are the shortening of the elytra and the transformation of the elytral venation (Coleoptera excluding Tshekardocoleidae), the formation of a closed subelytral space (Coleoptera excluding Tshekardocoleidae and Permocupedidae), the reduction of two apical antennomeres, and the loss of the broad prothoracic postcoxal bridge (Coleoptera excluding Tshekardocoleidae, Permocupedidae and Rhombocoleidae). Plesiomorphic features preserved in extant Archostemata are the tuberculate cuticle, the elytral pattern with parallel longitudinal ribs and window punctures, a mesoventrite with a transverse ridge, triangular mesocoxae with a distinct meron, and the exposed metatrochantin. The fossils included in the analyses do not only contribute to the reconstruction of character evolution but also influence the branching pattern. An understanding of the major evolutionary events in Coleoptera would not be possible without considering the rich fossil record of Permian and Mesozoic beetles.

The Willi Hennig Society, 2007.