New xyleborine (Coleoptera: Curculionidae: Scolytinae) genus with an Afrotropical-Neotropical distribution

<p>Plant-associated arthropods have been shown to cross large oceanic distances on floating plant material and to establish themselves on distant landmasses. Xyleborini (Coleoptera: Curculionidae: Scolytinae) ambrosia beetles occur in forests worldwide and are likely capable of  long range dispersal. In less than 20 million years, this group dispersed from Asia to tropical regions of Africa and South America. The phylogeny, taxonomy, and biogeography of one <em>Xyleborus </em>species group which occurs on both continents are reviewed for this study. Based on a well-resolved molecular phylogeny resulting from parsimony, likelihood, and Bayesian analyses of four gene loci, we describe a new monophyletic genus, <em>Xenoxylebora </em>Osborn, Smith &amp; Cognato, gen. nov., for this bicontinental <em>Xyleborus </em>species group with seven Afrotropical and six Neotropical species. Six new species are described: <em>Xenoxylebora pilosa </em>Osborn, Smith &amp; Cognato, sp. nov. from Africa, and <em>Xenoxylebora addenda </em>Osborn, Smith &amp; Cognato, sp. nov., <em>Xenoxylebora calculosa </em>Osborn, Smith &amp; Cognato, sp. nov., <em>Xenoxylebora hystricosa</em> Osborn, Smith &amp; Cognato, sp. nov., <em>Xenoxylebora serrata </em>Osborn, Smith &amp; Cognato, sp. nov., and <em>Xenoxylebora sulcata </em>Osborn, Smith &amp; Cognato, sp. nov., from South America. Seven new combinations from <em>Xyleborus </em>are proposed: <em>Xenoxylebora caudata</em> (Schedl, 1957) comb. nov., <em>Xenoxylebora collarti</em> (Eggers, 1932) comb. nov., <em>Xenoxylebora perdiligens</em> (Schedl, 1937) comb. nov., <em>Xenoxylebora sphenos</em> (Sampson, 1912) comb. nov., <em>Xenoxylebora subcrenulata</em> (Eggers, 1932) comb. nov., and <em>Xenoxylebora syzygii</em> (Nunberg, 1959) comb. nov. from Africa, and<em> Xenoxylebora neosphenos</em> (Schedl, 1976) comb. nov. from South America. One new synonym is proposed: <em>Xenoxylebora sphenos </em>(Sampson, 1912) =<em>Xyleborus tenellus </em>Schedl, 1957 syn. nov. Descriptions, diagnoses, images, and a key to the identification of all 13 species are provided. The sequence of colonization between Africa and South America is uncertain for <em>Xenoxylebora</em>. Prevailing ocean currents and predominant locality patterns observed for other organisms suggests an African <em>Xenoxylebora</em> origin.  However, the phylogeny, biogeographical analyses, and a calibrated divergence time suggests a possible South American origin for African <em>Xenoxylebora</em> (2.3 Ma, 95% HDP 4.5 – 0.6 Ma) which is supported by the occurrence of ocean counter currents between the continents and evidence of dispersal from South America to Africa among some plant and arthropod taxa.   </p>