| The Nearctic bark beetle genus Scolytus was revised based in part on a molecular phylogeny. Monophyly of the native species was tested using mitochondrial (COI) and nuclear (28S, CAD, ArgK) genes and 43 morphological characters in parsimony and Bayesian phylogenetic analyses. Parsimony analyses of molecular and combined datasets provided variable results while Bayesian analysis recovered most nodes with posterior probabilities >90%. Native angiosperm and conifer-feeding Scolytus spp. were recovered as paraphyletic. Twenty-five species were recognized. Four new synonyms were discovered: Scolytus praeceps LeConte 1868 (= S. abietis Blackman 1934; =S. opacus Blackman 1934), S. reflexus (= S. virgatus Bright 1972; = S. wickhami Blackman 1934). Two species were removed from synonymy: Scolytus fiskei Blackman 1934 and S. silvaticus Bright 1972. Neotypes were designated for the following species: Scolytus aztecus Wood 1967, S. hermosus Wood 1968 and S. mundus Wood 1968. A key, diagnosis, redescription, distribution, host records and images were provided for each species. The influence of plants in the diversification of herbivorous insects, specifically those that utilize moribund and dead hosts, is unclear. Scolytini, a diverse tribe of weevils, specialize on many different plant taxa as a source of food. The phylogenetics of the Scolytini were reconstructed using Bayesian analyses to examine the origin, test the monophyly of Scolytini genera, and illuminate patterns of host-use and feeding habits among the tribe. Analyses were based on COI, 28S, CAD and ArgK. Ancestral host usage was reconstructed using likelihood criteria. Diversification of the Scolytini generally occurred well after host taxa diversified, as a combination of host shifts and lineage tracking. Repeated independent shifts to the same hosts occurred. Diversification occurred on common and widespread hosts, there was a single origination of conifer-feeding from angiosperm-feeding species and evolution of fungus-feeding from phloem-feeding ancestors. Overall, the observed patterns of Scolytini host-use can be explained by a combination of the sequential evolution and host-use oscillation hypotheses.;The Neotropical bark beetle genera Cnemonyx Eichhoff 1868 and Scolytus Geoffroy1762 were reviewed as part of ongoing research into the higher-level taxonomy of the Scolytini. Ceratolepsis Chapuis 1869 was removed from synonymy with Cnemonyx and seven new combinations are reported: Ceratolepsis amazonicus Eggers 1929, C. boliviae (Blackman) 1943, C. hylurgoides (Schedl) 1948, C. insignis (Wood) 1969, C. jucundus Chapuis 1869, C. maculicornis Blandford 1896 and C. niger (Eggers) 1929. One new species was described: Scolytus rabagliatus. Cnemonyx setulosus (Eggers) 1929 was removed from synonymy with C. panamensis (Blandford) 1896. Four new synonyms were discovered: Ceratolepsis Chapuis (= Coptosomus Schedl 1952), Cnemonyx setulosus (Eggers) 1929 (= Cnemonyx similis (Eggers) 1929), Scolytus proximus Chapuis 1869 (= Scolytus brevicauda Wichmann 1915) and Scolytus thoracicus Chapuis 1869 (= Scolytus plaumanni Wood 2007). One new distribution record was reported: Scolytus multistriatus in South America (Brazil). |
