Pseudocryptic species, those that are difficult to diagnose using traditional taxonomic methods, are serious impediments for recognizing the introduction of non-native species. Rapid identification of species facilitates a rapid response to newly introduced species which can lessen their damaging effects. This situation is acute for known pest species such as xyleborine ambrosia beetles which are difficult to identify given minute morphological, often variable, diagnostic characters. These beetles have been introduced into non-native temperate regions and have caused economic and ecological havoc. In this study, we produced DNA-based phylogenies using four genes for individuals of Cyclorhipidion bodoanum (Reitter, 1913), C. distinguendum (Eggers, 1930), and C. pelliculosum (Eichhoff, 1878) sampled from their introduced and native Asian ranges and as well as other Cyclorhipidion species. In addition, we review subtle morphological characters for diagnostic potential for these similar species. Bayesian phylogenetic analysis produced well-resolved and supported phylogeny that provided evidence for multiple introductions of C. bodoanum and C. distinguendum into the US and the occurrence of pseudocryptic species. The ambrosia beetles Cyclorhipidion tenuigraphum (Schedl, 1953) and C. nemesis Smith & Cognato, sp. nov. are reported in North America for the first time. We find that the pattern of elytral interstrial setae is an unrealized source for the identification of Cyclorhipidion species. This study resulted in the recognition of six species adventive to the US with the revised status of C. californicum (Wood, 1975). All species known from North American are diagnosed, illustrated and a key is provided.

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