We revised the genera and species of Xyleborini (Coleoptera, Curculionidae: Scolytinae) recorded from New Guinea and neighboring islands. We examined more than 44,000 representatives of 282 species and 31 genera, including 264 type specimens. Established classification (Wood and Bright 1992; Bright and Skidmore 1997, 2002) and several recent cladistic and molecular analyses of Xyleborini guided our revisions. We used phylogenetically informative morphological characters inferred by these analyses to define genera and species. As a result, we describe new genera and species, but overall we reduce the number of previously described species through synonymies.

Three new genera are described: Ancipitis Hulcr and Cognato [type species Ancipitis puer (Eggers)]; Immanus Hulcr and Cognato [type species Immanus colossus (Blandford]; and Stictodex Hulcr and Cognato [type species Stictodex dimidiatus (Eggers)].

Ten new species are described: Amasa knizeki Hulcr and Cognato; Ambrosiophilus mogia Hulcr and Cognato; Arixyleborus simplicaudus Hulcr and Cognato; Beaverium rugipunctus Hulcr and Cognato; Cyclorhipidion artedilatatum Hulcr and Cognato; Cyclorhipidion spurlinum Hulcr and Cognato; Diuncus niger Hulcr and Cognato; Euwallacea andreae Hulcr and Cognato; Planiculus rodmanculus Hulcr and Cognato; Xyleborus devexipennis Hulcr and Cognato.

Twenty-one new combinations are made: Amasa truncatiformis (Eggers 1923) to Truncaudum; Ambrosiodmus colossus (Blandford 1896) to Immanus; Ambrosiodmus declivispinatus (Schedl 1969) to Xyleborus; Coptoborus bispinus (Schedl 1979) to Streptocranus; Coptodryas chimbui (Schedl 1973) to Microperus; Coptodryas fragosus (Schedl 1942) to Microperus; Coptodryas popondettae (Browne 1970) to Microperus; Coptoborus superbus (Schedl 1942) to Cyclorhipidion; Cyclorhipidion tuberculifer (Eggers 1923) to Truncaudum; Leptoxyleborus puer (Eggers 1923) to Ancipitis; Taphrodasus cuspidus (Schedl 1975) to Stictodex; Webbia similis (Eggers 1923) to Amasa; Xyleborus acanthurus (Lea 1910) to Immanus; Xyleborus curvatus Browne (1986) to Pseudowebbia; Xyleborus cyclopus Schedl (1940) to Debus; Xyleborus densatus Schedl (1979) to Euwallacea; Xyleborus dimidiatus (Eggers 1927) to Stictodex; Xyleborus latecornis Schedl (1969) to Debus; Xyleborus repandus Schedl (1942) to Cyclorhipidion; Xyleborus timidus Schedl (1973) to Euwallacea; Xyleborus truncaticauda Browne (1984) to Truncaudum.

Fifty-nine species are synonymized: Amasa anomala (Schedl) [= Amasa nakazawai (Browne 1984)]; Amasa resecta (Eggers) [= Amasa fulgens (Schedl 1975)]; Amasa schlichi (Stebbing) [= Amasa striatotruncatus (Schedl 1936), = Amasa umbratulus (Schedl 1975)]; Ambrosiophilus restrictus (Schedl) [= Ambrosiodmus incertus (Schedl 1969), = Xyleborus australis Schedl (1980a), = Xyleborus devius Schedl (1979)]; Ambrosiophilus semicarinatus (Schedl) [= Xyleborus nitens Browne (1984)]; Arixyleborus abruptus Schedl [= Arixyleborus iriani Browne (1983)]; Arixyleborus canaliculatus (Eggers) [= Arixyleborus cariniceps Schedl (1975)]; Arixyleborus minor (Eggers) [= Arixyleborus trux Schedl (1975)]; Arixyleborus puberulus (Blandford) [= Arixyleborus morio (Eggers 1923)]; Arixyleborus scabripennis (Blandford) [= Arixyleborus guttifer (Schedl 1955)]; Beaverium insulindicus (Eggers) [= Xyleborus annexus Schedl (1973), = Xyleborus depressurus Browne (1985)]; Beaverium perplexus (Schedl) [= Xyleborus platyurus Browne (1984)]; Beaverium sundaensis (Eggers) [= Xyleborus aplanatideclivis Schedl (1942)]; Cnestus aterrimus (Eggers) [= Cnestus pseudosuturalis Schedl (1964)]; Coptodryas popondettae (Browne 1970) [= Coptodryas docta (Schedl 1975)]; Cyclorhipidion apicipenne (Schedl) [= Cyclorhipidion anoplum (Schedl 1975)]; Cyclorhipidion bituberculatum (Eggers) [= Ambrosiodmus funestus (Schedl 1979), = Cyclorhipidion canarii (Browne 1984), = Cyclorhipidion revocabile (Schedl 1942), = Xyleborus abbreviatipennis Schedl (1973), = Xyleborus flavipennis Schedl (1979), = Xyleborus flavopilosus Schedl (1936)]; Cyclorhipidion multipunctatum (Browne) [= Xyleborus multipunctulus Browne (1984)]; Cyclorhipidion tuberculifer (Eggers 1923) [= Xyleborus hopeae Browne (1986)]; Debus latecornis (Schedl) [= Xyleborus opulentus Schedl (1975)]; Diuncus haberkorni (Eggers) [= Xyleborus approximatus Schedl (1951)]; Diuncus Justus (Schedl) [= Xyleborus apiculatus Schedl (1942), = Xyleborus ciliatoformis Schedl (1953b), = Xyleborus ciliatus Eggers (1940)]; Diuncus mesoleiulus (Schedl) [= Xyleborus brevicollis Browne (1984)]; Diuncus papatrae (Schedl) [= Xyleborus biuncus Browne (1984), = Xyleborus mucronatoides Schedl (1975)]; Eccoptopterus spinosus (Olivier) [= Eccoptopterus gracilipes (Eichhoff 1886), = Eccoptopterus Sagittarius Schedl (1939)]; Euwallacea destruens (Blandford) [= Euwallacea procerrimus (Schedl 1969)]; Euwallacea timidus (Schedl) [= Xyleborus granulipes Schedl (1973)]; Leptoxyleborus puer (Eggers 1923) [= Leptoxyleborus ceramensis (Schedl 1937)]; Leptoxyleborus sordicauda (Motschulsky) [= Leptoxyleborus concisus (Blandford 1894)]; Microperus reddens (Sampson) [= Coptodryas artegrapha (Schedl 1942), = Coptodryas extensa (Schedl 1955)]; Pseudowebbia squamatilis (Schedl) [= Webbia denticulatus Browne (1983)]; Schedlia usitata (Schedl) [= Schedlia convexa Bright (1980), = Schedlia paraconvexa Bright (1980)]; Euwallacea andamanensis (Blandford) [= Euwallacea talumalai (Browne 1966)]; Webbia pabo Sampson [= Webbia quadricinctus Schedl (1972)]; Webbia similis (Eggers 1923) [= Amasa cylindriformis (Schedl 1942), = Amasa tereticollis (Schedl 1951)]; Xyleborinus exiguus (Walker) [= Xyleborinus ankius (Schedl 1975), = Xyleborinus perexiguus (Schedl 1971)]; Xyleborus bidentatus (Motschulsky) [= Xyleborus subcostatus Eichhoff (1869)]; Xyleborus dimidiatus (Eggers 1927) [= Xyleborus cruciatus Schedl (1973), = Xyleborus decumans Schedl (1953), = Xyleborus tunggali Schedl (1936)]; Xyleborus judenkoi Schedl [= Xyleborus immitatrix Schedl (1975)]; and Xyleborus perforans Wollaston [= Xyleborus cognatus Blandford (1896)].

We designate a lectotype for Cyclorhipidion repandum Schedl (1942). In addition to dicotomous keys to the genera and species, the monograph is complemented by photographs of all species and multiple-entry electronic keys to all species and genera, available online at http://www.ambrosia-symbiosis.org/PNG_Xyleborini. Because all the genera and many species that occur in New Guinea also occur throughout the Eastern Paleotropic region, the presented reclassification of the Xyleborini is applicable to a larger geographical scale, in many cases to the entire world.