Systematics and Cladistics of the genus Megalostomiswith Biogeographic considerations (Coleoptera: Cryptocephalinae)

AGRAIN, F.; ROIG JUÑENT, SERGIO

SYSTEMATIC ENTOMOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2011 vol. 36 p. 672 - 704

0307-6970

We present a cladistic analysis of the subtribe Megalostomina, a Neotropical group of ?case bearer? leaf beetles. A comparative study of the external and internal adult morphology of Clytrini was undertaken. New characters are described for the subtribe Megalostomina, from the internal sac of aedeagus, which provides useful phylogenetic signal. More than 180 photographs illustrating the most important characters (74 characters and their respective states) used in the cladistic analysis are provided. The cladistic analysis of 57 terminal taxa and 95 characters was undertaken, under equal weights, and also using implied weights as a means to down-weight homoplasious characters. We test the monophyly and explore intergeneric relationships of the subtribe Megalostomina, and reconstruct the relationships among the species of Megalostomis Chevrolat. We confirm the subgenera of Megalostomis of previous classifications are unnatural. The 42 species recognized can be assigned either to a group containing mostly species of North and Central America, or to a larger one of mostly South American species. However, support is low and we refrain from formal naming pending systematic revision of all Megalostomina. Our cladistic analyses support changes in the generic classification of the subtribe Megalostomina: Coleorozena Moldenke 1981, syn. nov. of Coscinoptera Lacordaire 1848; Coleothorpa Moldenke 1981, syn. nov. of Coscinoptera Lacordaire 1848; and Euryscopa (Coleoguerina) Moldenke 1981, syn. nov. of Coscinoptera Lacordaire 1848. Furthermore, six formerly recognized subgenera of Megalostomis are considered junior synonyms of Megalostomis Chevrolat 1837: M. (Minturnia) Lacordaire 1848, syn. nov.; M. (Heterostomis) Lacordaire 1848, syn. nov.; M. (Scaphigenia) Lacordaire 1848, syn. nov.; M. (Snellingia) Moldenke 1981, syn. nov.; M. (Coleobyersa) Moldenke 1981, syn. nov.; and M. (Pygidiocarina) Moldenke 1970, syn. nov. Thus, no subgenera are recognized within Megalostomis. Previous hypotheses on Clytrini biogeography were revisited by considering new biogeographic and phylogenetic knowledge, including the evidences from our cladistics analysis. We hypothesize that the origin of Clytrini was situated in the tropical/subtropical region of Gondwana, when South America, Africa, Madagascar and India were connected. During the Cenozoic, the new configuration of the tectonic plates allowed the dispersal of Clytrina to the Palearctic and Nearctic regions, as well as the dispersion of Babiina and Megalostomina through the Nearctic. This hypothesis of tropical origin of clytrines explains the observed distribution patterns and is expected to be contrasted in future works.