Molecular and Morphological Phylogenetic Analyses of New World Cycad Beetles: What They Reveal about Cycad Evolution in the New World.

Two major lineages of beetles inhabit cycad cones in the New World: weevils (Curculionoidea) in the subtribe Allocorynina, including the genera <italic>Notorhopalotria</italic> Tang and O’Brien, <italic>Parallocorynus</italic> Voss, <italic>Protocorynus</italic> O’Brien and Tang and <italic>Rhopalotria</italic> Chevrolat, and beetles in the family Erotylidae, including the genus <italic>Pharaxonotha</italic> Reitter. Analysis of the 16S ribosomal RNA (rRNA) mitochondrial gene as well as cladistic analysis of morphological characters of the weevils indicate four major radiations, with a probable origin on the cycad genus <italic>Dioon</italic> Lindl. and comparatively recent host shifts onto <italic>Zamia</italic> L. Analysis of the 16S rRNA gene for erotylid beetles indicates that an undescribed genus restricted to New World <italic>Ceratozamia</italic> Brongn. is the most early-diverging clade, and this lineage is sister to a large radiation of the genus <italic>Pharaxonotha</italic> onto <italic>Zamia</italic>, with apparent host shifts onto <italic>Dioon</italic> and <italic>Ceratozamia</italic>. Analysis of beetles are in accord with current models of continental drift in the Caribbean basin, support some proposed species groupings of cycads, but not others, and suggest that pollinator type may impact population genetic structure in their host cycads. [ABSTRACT FROM AUTHOR]