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The phylogenetic relationships among the Japanese members of the genus Eubrianax (Coleoptera: Psephenidae) were examined using the mitochondrial cytochrome oxidase subunit I ( COI) gene and nuclear 28S rRNA gene sequences. Based on the molecular phylogeny as well as morphological features, the species status of Eubrianax brunneicornisNakane, 1952 was proposed. The phylogenetic analyses recovered monophyly of the previously proposed pellucidus species group with four Japanese species, whereas a single Japanese species of the granicollis group was included in the lineage of the ramicornis group with five Japanese species. The divergence times of the species were estimated by dating the phylogenetic tree against the fossil record and a molecular clock based on the COI gene. The divergence of the Japanese species was inferred to have occurred during the Pliocene epoch. [ABSTRACT FROM AUTHOR]

Molecular phylogenies of the genus Platycerus in Japan were characterized based on the nuclear 28S ribosomal RNA and mitochondrial cytochrome oxidase subunit I ( COI) genes. These analyses, combined with our previous morphological information, revealed a detailed diversification process of Platycerus in Japan, as well as estimates of their divergence times. Japanese species were monophyletic and were inferred to have diverged to the acuticollis species group and all other species ca 1.69 Mya. The acuticollis species group then appeared to split into P. viridicuprus and a group including P. takakuwai, P. albisomni and P. acuticollis ca 1.26 Mya. Other specific divergences have occurred primarily since ca 0.33 Mya. Comparing the molecular trees and the morphological tree, we also found introgression of the COI gene in some species. Genetic divergence of Platycerus has occurred intensely in southwestern Japan. [ABSTRACT FROM AUTHOR]

Two psephenid beetles, Eubrianax granicollis Lewis and E. ramicornis Kiesenwetter, are common species on the main islands of Japan (i.e. Honshu, Shikoku and Kyushu), but diagnostic characters for larval identification are unknown. Two types of field-collected Eubrianax larvae from Honshu and Kyushu were discriminated based on the distributions of granules on the dorsal surface. These larvae were assigned to E. granicollis and E. ramicornis by comparing them with larvae of the two species obtained via laboratory rearing. The two species were also identified unambiguously on the basis of their mitochondrial cytochrome oxidase subunit I (COI) gene sequences. Larval and pupal morphology are described based on laboratory-reared specimens. [ABSTRACT FROM AUTHOR]

We examined the genetic structures of 13 Japanese populations of an ambrosia beetle, Xylosandrus germanus (Curculionidae: Scolytinae), to understand the effects of geographical barriers on the colonization dynamics of this species. The genetic structure was studied using portions of the mitochondrial cytochrome oxidase I ( COI) gene. A phylogenetic analysis revealed three distinct lineages (clades A, B and C) within X. germanus. Clade A contained 21 haplotypes from all 13 populations; whereas clade B contained eight haplotypes from Hokkaido (Sapporo and Furano), Iwate and Nagano populations; and clade C contained only a single a haplotype from the Hokkaido (Furano) population. In the analysis of molecular variance (amova), the greatest amount of genetic variation was detected between populations in Hokkaido and those in Honshu and other southern islands. Between these two groups of populations, all the values of the coefficient of gene differentiation were significantly larger than zero, except for the Hokkaido (Sapporo) versus Nagano comparison. Our results confirm that for X. germanus, gene flow has been interrupted between Hokkaido and Honshu since the last glacial maximum. [ABSTRACT FROM AUTHOR]