Our study is focused on members of the weevil subfamily Cossoninae associated with the conifer genus Araucaria whose distribution in the southern-most continents (Australia and South America) is suggestive of an ancient origin of these associations. Previous molecular studies corroborate the ancestral association with the genus Araucaria of both South American and Australian Tomicini bark beetles (sister group to the Cossoninae) and Bayesian estimation of divergence times indicates that the divergence between the Australian and the South American Araucaria-feeding taxa occurred at the very latest in the Cretaceous/Paleocene border and that the age of the first Scolytinae- Araucaria association would then be during the later stages of the Late Cretaceous.
Indeed, the distributions and associations of the genera in the Cossoninae tribe Araucarini are similarly Gondwanan. The South American Araucarius and the Australian Coptocorynus, Mastersinella and Xenocnema are all associated with Araucariaceae, while New Zealand harbors Xenocnema (also on New Caledonia) plus Inosomus, the sole genus associated with Podocarpaceae, the sister group to Araucariaceae. The remaining genus in Araucariini, Amorphocereus, is associated with Cycadaceae in South Africa, where Araucaria is now extinct. If these associations of Tomicini and Araucariini with Araucariaceae reflect descent from a shared ancestor, the origin of the association would be even deeper in the Cretaceous. One approach to this problem is to resolve the position of members of the tribe Araucarini within the Cossoninae, using nucleotide sequences of ribosomal nuclear genes (18sand 28s) and amino acid sequences of mitochondrial protein coding genes (COI), to test for a basal position for the Araucaria associated Cossoninae. If it turns out that these plants were colonized independently by Cossoninae weevils they would provide a comparison of closely related (sister groups) with comparable associations.
Species 1: Coleoptera Curculionidae Araucarius major
Species 2: Coleoptera Curculionidae Cossonus linearis
Keywords: biogeography, host associations
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