Two major lineages of beetles inhabit cycad cones in the New World: weevils (Curculionoidea) in the subtribe Allocorynina, including the genera Notorhopalotria Tang and O'Brien, Parallocorynus Voss, Protocorynus O'Brien and Tang and Rhopalotria Chevrolat, and beetles in the family Erotylidae, including the genus Pharaxonotha 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 Dioon Lindl. and comparatively recent host shifts onto Zamia L. Analysis of the 16S rRNA gene for erotylid beetles indicates that an undescribed genus restricted to New World Ceratozamia Brongn. is the most early-diverging clade, and this lineage is sister to a large radiation of the genus Pharaxonotha onto Zamia, with apparent host shifts onto Dioon and Ceratozamia. 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.

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The genus Cycadophila Xu, Tang & Skelley (Coleoptera: Erotylidae: Pharaxonothinae) associated with Cycas L. (Cycadacaeae) in Asia is reviewed. Strobilophila, new subgenus, with five species is described: Cycadophila (Strobilophila) assamensis new species, C. (S.) hiepi new species, C. (S.) kwaiensis new species, C. (S.) tansachai new species and C. (S.) yangi new species, all associated with Cycas. For the nominate subgenus Cycadophila eight new species are described, Cycadophila (Cycadophila) abyssa new species, C. (C.) collina new species,C. (C.) samara new species, C. (C.) convexa new species, C. (C.) cyclochasma new species, C. (C.) eurynota new species, C. (C.) papua new species, and C. (C.) torquata new species and four new generic combinations are proposed: C. (C.) vittata (Arrow) new combination, C. (C.) discimaculata (Mader) new combination, C. (C.) intermedia (Chûjô) new combination, and C. (C.) lata (Grouvelle) new combination. Only the first three listed species of the nominate subgenus have known associations with Cycas. Species are distinguished on the basis of morphology and/or by analysis of 16S rRNA gene sequences. The larva of subgenus Strobilophila is described based on individuals collected together with adults and matched with analysis of 16S rRNA gene sequences. Keys to subgenera and species of known adults and larvae are provided.

Asian species assigned to Pharaxonotha Reitter formed a separate clade from New World species of the genus and are distinguished on the basis of morphology and analysis of 16S rRNA gene sequences. Cycadophila, new genus, is described based on a consideration of four Asian species in comparison with New World Pharaxonotha. This new genus includes two new species (Cycadophila debaonica new species and Cycadophila fupingensis new species) and two previously described species (Cycadophila nigra (Gorham) new combination and Cycadophila yunnanensis (Grouvelle) new combination). These latter two may represent species complexes. Lectotypes are designated for Thallis nigra Gorham and Pharaxonotha yunnanensis Grouvelle. Larvae of C. debaonica and C. fupingensis are described based on individuals collected on the cones of Cycas debaoensis Y. C. Zhong & C. J. Chen (Cycadaceae), a cycad native to Guangxi and Yunnan provinces, China.