Java, Indonesia is one of the most biodiverse regions of the world. However, knowledge of its biodiversity is threatened by both continued habitat conversion and the lack of domestic research capacity. The aim of this multinational project was to document the species of bark and ambrosia beetles (Curculionidae: Platypodinae and Scolytinae) within the protected forested areas of Universitas Brawijaya, East Java. One new platypodine and three new scolytine species are described: Crossotarsus gunungapi Hulcr, Tarno, and Levia, new species, Cosmoderes arjuno Johnson, new species, Cosmoderes opacus Johnson, new species, and Amasa brawijaya Smith, new species. Six Platypodinae and 28 Scolytinae species are documented. The goal of this checklist is not to be exhaustive, but rather to provide a baseline in the recently re-established multinational collaboration between forest entomologists in Indonesia and the USA. The broader aim of the project is equitable benefit-sharing; therefore, this paper not only delivers new data about biodiversity in Indonesia but also provides training of the new generation of local forest entomologists.

A comprehensive list of the currently (as of 17 November 2025) valid taxa of bark and ambrosia beetles of the world (Curculionidae: Scolytinae) is presented, including all tribes, genera, species (6516), and subspecies. The high diversity of scolytine species, their biosecurity significance, and the rapidly advancing understanding of their phylogenetic relationships has resulted in decentralized and often incorrect usage of names. The list represents species names accepted and used in compliance with the International Code of Zoological Nomenclature and a consensus of name usage by the community of active systematists. Species names listed here are bona fide hypotheses of biological species, but not always of confirmed biological entities; instead, the list aims to provide a foundation for the subsequent taxonomic, biological, and phylogenetic work on species resolution, and for biodiversity data management. The list is presented as a formatted checklist, as well as a Darwin-core format enabling interpolation into biodiversity information systems. Two replacement names were needed to resolve homonyms, Hylastes woodi Johnson, nom. nov. (= Hylastes niger Wood, 1974) and Taphrorychus krivolutskayae Johnson, nom. nov. (= Dryocoetes aceris Krivolutskaya, 1968).

A synopsis of the West (Peninsular) Malaysian fauna of platypodine pinhole borer beetles is provided with information on local and world distribution, host trees, biology and taxonomy. One hundred and thirty-eight species are recorded from West Malaysia, eight for the first time. Diapus borneensis Browne comb. res. and Diapus pendleburyi Schedl comb. res. are restored to Diapus Chapuis from Genyocerus Motschulsky. Platypus philippinensis (Schedl) comb. res. is restored to Platypus Herbst from Dendroplatypus Browne. Attention is drawn to the presence of wax glands on the elytra as a possible synapomorphy defining the genus Genyocerus, and to the probable polyphyly of Peroplatypus Wood and Treptoplatypus Schedl. We also list 16 species for which 'Malaya' is included in the distribution in various catalogues, but for which we have been unable to find published records or see West Malaysian specimens. These records require confirmation.

Anthropogenic disturbances, such as forest conversion, have a profound impact on species distributions and biodiversity in tropical forests. This study aimed to determine the diversity and distribution of bark and ambrosia beetles (Curculionidae: Scolytinae and Platypodinae) across three forest types: Primary Forest (PF), Disturbed Forest (DF), and Rubber Plantation (RP) in southern Sabah, Malaysia. We analyzed biweekly data obtained from ethanol-baited traps over three years, from April 2017 to May 2020, which included 7257 individuals from 154 species. The dominant species remained the same across all forest types. However, species composition was highly stochastic and unpredictable between forest types. The abundance and number of species were highest in RP but lowest in DF. Indigenous forest use in DF mostly for fuel likely reduced the resources for the beetles. Open canopy structure in RP probably increased the number of flying beetles. Although adjacent to PF, RP displayed a distinct species composition predominantly associated with rubber trees. These findings underscore the anthropogenic impact on beetle assemblages due to forest use and emphasize the need for sustainable forest management practices to prevent biodiversity loss and maintain ecosystem stability.

A checklist of the West Malaysian fauna is provided with information on local and world distribution, host trees, biology and taxonomy. Three hundred seventy-six species are recorded from Malaya, 33 for the first time. Five new species are described: Asiophilus bukiticola Smith, Beaver & Cognato sp. nov., Cyclorhipidion brownei Smith, Beaver & Cognato sp. nov., Euwallacea frimensis Smith, Beaver & Cognato sp. nov., Euwallacea phrixosoma Smith, Beaver & Cognato sp. nov., and Microperus pasohanthus Smith, Beaver & Cognato sp. nov. Three species are removed from synonymy and reinstated as valid species: Euwallacea barbatus (Hagedorn, 1910), Euwallacea pseudobarbatus (Schedl, 1942), Euwallacea rudis (Eggers, 1930). Two new combinations are proposed: Ancipitis scabrior (Schedl) comb. nov. from Leptoxyleborus Wood, 1980; Xylosandrus mascareniformis (Eggers, 1972) comb. nov. from Xyleborus Eichhoff, 1864. Two new synonyms are proposed: Coccotrypesgedeanus (Eggers, 1936) (= Xyleborus despectus Schedl, 1975 syn. nov.) and Arixyleborus scapularis (Schedl, 1942) (=Xyleborus magnus Browne, 1985 syn. nov.).

A new species, Cryptoxyleborus brevicauda Sittichaya & Beaver sp. nov., , is described from the South of Thailand. A list of Cryptoxyleborus species found in Thailand with their provincial distributions and habitat types, and a key to Thai species are provided.

Four new species of Euwallacea Hopkins, 1915, Euwallacea chiangdao Sittichaya, Smith, and Beaver, new species, Euwallacea congruens Sittichaya, Smith, and Beaver, new species, Euwallacea plenilunium Sittichaya, Smith, and Beaver, new species, and Euwallacea sulcatus Sittichaya, Smith, and Beaver, new species, are described from Thailand. Habitus photographs and diagnoses are provided with differential characters to separate them from other Euwallacea species. With the inclusion of the species described and recorded herein, the diversity of Euwallacea is increased to 81 species, of which 17 occur in Thailand. A synoptic list with updated species distributions within Thailand is provided.

A new species of ambrosia beetle Indocryphalus chiyui Lin & Beaver (tribe Xyloterini LeConte, 1876) from Taiwan is described. The species is monogamous and xylomycetophagous, breeding in Castanopsis cuspidata var. carlesii (Hemsl.) Yamazaki (Fagaceae). Indocryphalus sordidus (Blandford) is recorded for the first time from Taiwan. Diagnostic characters, biological data and a key to species of Indocryphalus in Taiwan are provided.

Micrapate spinula Liu, sp. nov., is described from the cerrado savanna biome of Brazil (Mato Grosso do Sul and Minas Gerais), together with information on its biology and natural enemies. A key to the Micrapate species known from Brazil is provided.

Four new species, Arixyleborus halabala Sittichaya, Beaver & Smith sp. nov. , Arixyleborus longicauda Sittichaya, Beaver & Smith sp. nov. , Arixyleborus vellus Sittichaya, Beaver & Smith sp. nov. are described from Thailand, and Arixyleborus liratus Sittichaya, Beaver & Smith sp. nov. from Thailand and East Malaysia (Sabah). With the inclusion of the species described here, the diversity of Arixyleborus is increased to 46 species, of which 20 occur in Thailand. A synoptic list with distributions and habitat types is provided.

Only 20% of the estimated five million species of insects on Earth are named despite over 240 years of taxonomy. Yet insects are poorly represented in protected area assessments, and insect declines are of concern globally. Here we explore how to increase the discovery of new species and understanding of this group through analysis of 10,097 tropical rainforest bark beetles (Scolytinae) from eight different ecological studies using beetles between 2000 and 2018 in the Australian Wet Tropics. Of the 107 species identified, 58 are undescribed: an increase of 35% on the 166 species known from Australia. As hypothesised, new species are significantly smaller, less abundant and less widespread than described species making them more extinction prone than named species. Rarefaction indicates doubling sampling would increase the number of species by 17. Flight Interception Traps (FIT) collected 84% of individuals and 98% of species confirming the effectiveness of a single sampling method for some beetles. Increased locations and collection from the canopy may sample further species rather than additional collecting methods. Scolytines are relatively well studied with a cadre of taxonomists at the forefront of using modern methods to resolve formerly intractable groups. These new species are more likely to be named than others in many other beetle groups where taxonomy has largely stalled. To increase species description rates and to avoid most species becoming extinct before being named, we call on taxonomists to use new character systems provided by DNA methods and to look at working with Artificial Intelligence tools.Significance Statement In an era of rapid biodiversity loss, current conservation decisions for insects will continue to be based on a small and almost certainly biased sample of the world’s biota until more species are named. We demonstrate how large-scale sampling can dramatically increase the number of species discovered for one group of beetles and how these undescribed species are significantly smaller, less abundant and less widespread than named species. The identification and determination of undescribed species is rarely possible except when taxonomic expertise is available, as in the present study. Addressing the insect taxonomic bottleneck and increasing the rate of description will require the adoption of new and developing tools.### Competing Interest StatementThe authors have declared no competing interest.

We show, using molecular data, that the enigmatic genus Urocorthylus Petrov, Mandelshtam & Beaver from Southeast Asia belongs in the scolytine tribe, Dryocoetini, and not in the almost wholly American tribe Corthylini, where it was originally placed. The male of Urocorthylus hirtellus Petrov, Mandelshtam & Beaver is described and figured for the first time, and new records from China are presented. Urocorthylus hirtellus is a bark beetle, and not an ambrosia beetle as originally hypothesised. Keys are provided to the genus within the Dryocoetini, and to the two species included in the genus.

A new genus, Plesioxylion Liu & Beaver gen. nov., is described for Amintinus gambianus Borowski, 2018 from West Africa with a more detailed description and new records of both sexes. We also provide a key to the ten Afrotropical genera in the tribe Xyloperthini Lesne, 1921 as the baseline information for a future study.

We describe Polycaon sinensis sp. n., the first Asian species of this otherwise American genus, and Melalgus plesiobatillus sp. n., from the same montane locality in China (Zhejiang). The following new synonym is proposed: Melalgus batillus (Lesne) (=Melalgus japonicum Chûjô syn. n.). We comment on the species, Melalgus borneensis (Lesne) sensu Borowski & Węgrzynowicz (2012), and provide a key to the Chinese species of Polycaoninae.

Five new species, Anisandrus montanus sp. nov. , A. phithakpa sp. nov. , A. tanaosi sp. nov. , A. triton sp. nov. , and A. uniseriatus sp. nov. are described from Thailand. Anisandrus carinensis (Eggers, 1923) is reported from Thailand for the first time and A. apicalis is removed from the Thai fauna. With the inclusion of the species described and recorded here, the diversity of Anisandrus is increased to 40 species, of which 11 occur in Thailand. A synoptic list and a key to the Anisandrus of Thailand are presented.

Four new species, Webbia aculeata Sittichaya, Smith & Beaver sp. nov., Webbia granulosa Sittichaya, Smith & Beaver sp. nov., Webbia planicauda Beaver, Sittichaya & Smith sp. nov., and Webbia spinosulcata Sittichaya, Smith & Beaver sp. nov., are described. Arixyleborus dissimilis (Eggers, 1923), and Arixyleborus orbiculatus (Eggers, 1923) are transferred to Webbia. Two new synonyms and a new combination are proposed: Webbia dissimilis (Eggers, 1923) comb. nov. (=Webbia costulatula Schedl, 1953 syn. nov.); Webbia hatanakai Browne, 1986 (=Webbia turbinata Maiti & Saha, 1986 syn. nov.). A lectotype is designated for Webbia orbiculata (Eggers, 1923) comb. res.. Three species, Webbia bituberculata (Browne, 1977), Webbia subuculae (Browne, 1962), and Webbia suturalis Browne, 1955 are recorded in Thailand for the first time. With the inclusion of the Webbia species described and recorded herein, the diversity of Webbia is increased to 41 species. A key is given to the 16 species recorded from Thailand.

A new species of bark beetle Craniodicticus cinnamomi Lin & Beaver (tribe Carphodicticini Wood, 1971) from Taiwan is described. The species is phloeophagous and harem polygynous, breeding in Cinnamomum insulari-montanum (Lauraceae). A key to the species of Craniodicticus is provided.

The powder post beetles (Coleoptera: Bostrichidae) (except Lyctinae) of Yunnan Province in Southwest China are reviewed for the first time. Keys to twenty-six genera and fifty-two species from the Yunnan region are provided. One new genus and seven new species are described: Dinoderus (Dinoderastes) hongheensis sp. nov., Dinoderus (Dinoderastes) nanxiheensis sp. nov., Gracilenta yingjiangensis gen. nov., sp. nov., Calonistes vittatus sp. nov., Calophagus colombiana sp. nov., Xylodrypta guochuanii sp. nov. and Xylodrypta zhenghei sp. nov.. Fourteen species are recorded in China for the first time. The bostrichid fauna of Yunnan is compared with those of the neighbouring bio-geographically related Southeast Asian and Himalayan regions. The fauna has a close affinity with that of tropical Southeast Asia and a much weaker relationship with the Palearctic region. The differences with the Himalayas may reflect the separate evolutionary and complex geological history of the two areas.

An ongoing study of the ambrosia beetle tribe Xyleborini has resulted in numerous taxonomic changes mostly representing new generic/species combinations which remove species from the once all-encompassing Xyleborus Eichhoff, 1864 to other genera based on revised taxonomic concepts. These changes are here listed. Terminalinus Hopkins, 1915 is removed from synonymy with Cyclorhipidion Hagedorn, 1912 and reinstated as a valid genus. Five species are removed from synonymy and reinstated as valid species: Amasa brevipennis (Schedl, 1971), Amasa fulgens (Schedl, 1975), Ambrosiophilus immitatrix (Schedl, 1975), Ambrosiophilus semirufus (Schedl, 1959), Microperus leprosulus (Schedl, 1936). The following 97 new or restored combinations are proposed: Ambrosiophilus bispinosulus (Schedl, 1961) comb. nov., Ambrosiophilus compressus (Lea, 1894) comb. nov., Ambrosiophilus latecompressus (Schedl, 1936) comb. nov., Ambrosiophilus pertortuosus (Schedl, 1942) comb. nov., Ambrosiophilus tomicoides (Eggers, 1923) comb. nov., Ambrosiophilus tortuosus (Schedl, 1942) comb. nov., Euwallacea obliquecauda (Motschulsky, 1863) comb. nov., all from Ambrosiodmus Hopkins, 1915; Coptodryas decepta (Schedl, 1979) comb. nov., Microperus pusillus (Eggers, 1927) comb. nov., both from Arixyleborus Hopkins, 1915; Coptodryas pseudopunctula (Schedl, 1942) comb. nov., from Cnestus Sampson, 1911; Microperus abbreviatus (Schedl, 1942) comb. nov., Microperus amphicauda (Browne, 1986) comb. nov., Microperus borneensis (Browne, 1986) comb. nov., Microperus comptus (Sampson, 1919) comb. nov., Microperus gorontalosus (Schedl, 1939) comb. nov., Microperus pullus (Schedl, 1952) comb. nov., Microperus tenellus (Schedl, 1959) comb. nov., Microperus vafer Schedl, 1957 comb. nov., all from Coptodryas Hopkins, 1915; Ambrosiophilus pityogenes (Schedl, 1936) comb. nov., Arixyleborus scapularis (Schedl, 1942) comb. nov., Beaverium dihingicum (Wood, 1992) comb. nov., Beaverium rufonitidus (Schedl, 1951) comb. nov., Coptodryas brevior (Eggers) comb. nov., Terminalinus dipterocarpi Hopkins, 1915 comb. res., Terminalinus sexspinatus (Schedl, 1935) comb. nov., Terminalinus terminaliae (Hopkins, 1915) comb. res., Truncaudum leverensis (Browne, 1986) comb. nov., all from Cyclorhipidion Hagedorn, 1912; Planiculus kororensis (Wood, 1960) comb. nov., Planiculus loricatus (Schedl, 1933) comb. nov., Planiculus murudensis (Browne, 1965) comb. nov., all from Euwallacea Reitter, 1915; Terminalinus anisopterae (Browne, 1983) comb. nov., Terminalinus indigens (Schedl, 1955) comb. nov., Terminalinus macropterus (Schedl, 1935) comb. nov., Terminalinus major (Stebbing, 1909) comb. nov., Terminalinus pilifer (Eggers, 1923) comb. nov., Terminalinus posticepilosus (Schedl, 1951) comb. res., Terminalinus pseudopilifer (Schedl, 1936) comb. nov., Terminalinus sulcinoides (Schedl, 1974) comb. nov., all from Fortiborus Hulcr & Cognato, 2010; Microperus micrographus (Schedl, 1958) comb. nov., Microperus truncatipennis (Schedl, 1961) comb. nov., both from Xyleborinus Reitter, 1913; Ambrosiophilus immitatrix (Schedl, 1975) comb. nov., Ambrosiophilus semirufus (Schedl, 1959) comb. nov., Arixyleborus crenulatus (Eggers, 1920) comb. nov., Arixyleborus strombosiopsis (Schedl, 1957) comb. nov., Beaverium batoensis (Eggers, 1923) comb. nov., Beaverium calvus (Schedl, 1942) comb. nov., Beaverium obstipus (Schedl, 1935) comb. nov., Beaverium rufus (Schedl, 1951) comb. nov., Coptodryas cuneola (Eggers, 1927) comb. nov., Cyclorhipidion amanicum (Hagedorn, 1910) comb. nov., Cyclorhipidion impar (Eggers, 1927) comb. nov., Cyclorhipidion inaequale (Schedl, 1934) comb. nov., Cyclorhipidion kajangensis (Schedl, 1942) comb. nov., Cyclorhipidion obiensis (Browne, 1980) comb. nov., Cyclorhipidion obtusatum (Schedl, 1972) comb. nov., Cyclorhipidion perpunctatum (Schedl, 1971) comb. nov., Cyclorhipidion repositum (Schedl) comb. nov., Cyclorhipidion separandum (Schedl, 1971) comb. nov., Debus abscissus (Browne, 1974) comb. nov., Debus amplexicauda (Hagedorn, 1910) comb. nov., Debus armillatus (Schedl, 1933) comb. nov., Debus balbalanus (Eggers 1927) comb. nov., Debus blandus (Schedl, 1954) comb. nov., Debus cavatus (Browne, 1980) comb. nov., Debus cylindromorphus (Eggers, 1927) comb. nov., Debus dentatus (Blandford, 1895) comb. nov., Debus excavus (Schedl, 1964) comb. nov., Debus fischeri (Hagedorn, 1908) comb. nov., Debus hatanakai (Browne, 1983) comb. nov., Debus insitivus (Schedl, 1959) comb. nov., Debus persimilis (Eggers, 1927) comb. nov., Debus subdentatus (Browne, 1974) comb. nov., Debus trispinatus (Browne, 1981) comb. nov., Diuncus taxicornis (Schedl, 1971) comb. nov., Euwallacea agathis (Browne, 1984) comb. nov., Euwallacea assimilis (Eggers, 1927) comb. nov., Euwallacea bryanti (Sampson, 1919) comb. nov., Euwallacea latecarinatus (Schedl, 1936) comb. nov., Euwallacea pseudorudis (Schedl, 1951) comb. nov., Euwallacea semipolitus (Schedl, 1951) comb. nov., Euwallacea temetiuicus (Beeson, 1935) comb. nov., Immanus duploarmatus (Browne, 1962) comb. nov., Leptoxyleborus sublinearis (Eggers, 1940) comb. nov., Peridryocoetes pinguis (Browne, 1983) (Dryocoetini) comb. nov., Stictodex halli (Schedl, 1954) comb. nov., Stictodex rimulosus (Schedl, 1959) comb. nov., Terminalinus granurum (Browne, 1980) comb. nov., Terminalinus indonesianus (Browne, 1984) comb. nov., Terminalinus moluccanus (Browne, 1985) comb. nov., Terminalinus pseudomajor (Schedl, 1951) comb. nov., Terminalinus sublongus (Eggers, 1927) comb. nov., Terminalinus takeharai (Browne) comb. nov., Terminalinus xanthophyllus (Schedl, 1942) comb. res., Tricosa abberrans (Schedl, 1959) comb. nov., Xenoxylebora truncatula (Schedl, 1957) comb. nov., Xyleborinus figuratus (Schedl, 1959) comb. nov., Xylosandrus cancellatus (Eggers, 1936) comb. nov., all from Xyleborus. Fifteen new synonyms are proposed: Anisandrus ursulus (Eggers, 1923)(= Xyleborus lativentris Schedl, 1942 syn. nov.); Cyclorhipidion amanicus (Hagedorn, 1910)(= Xyleborus jongaensis Schedl, 1941 syn. nov.); Cyclorhipidion bodoanum (Reitter, 1913) (= Xyleborus takinoyensis Murayama, 1953 syn. nov.); Cyclorhipidion pelliculosum (Eichhoff, 1878) (= Xyleborus okinosenensis Murayama, 1961 syn. nov.); Cyclorhipidion repositum (Schedl, 1942) (= Xyleborus pruinosulus Browne, 1979 syn. nov.); Debus persimilis (Eggers, 1927) (= Xyleborus subdolosus Schedl, 1942c syn. nov.); Debus robustipennis (Schedl, 1954) (= Xyleborus interponens Schedl, 1954 syn. nov.); Euwallacea destruens (Blandford, 1896) (= Xyleborus procerior Schedl, 1942 syn. nov.); Euwallacea nigrosetosus (Schedl, 1939) (= Xyleborus nigripennis Schedl, 1951 syn. nov.); Euwallacea siporanus (Hagedorn, 1910) (= Xyleborus perakensis Schedl, 1942 syn. nov.); Microperus quercicola (Eggers, 1926) (= Xyleborus semistriatus Schedl, 1971 syn. nov.); Stictodex dimidiatus (Eggers, 1927) (= Xyleborus spicatus Browne, 1986 syn. nov.); Stictodex halli (Schedl, 1954) (= Xyleborus cuspidus Schedl, 1975 syn. nov.); Terminalinus Hopkins, 1915 (= Fortiborus Hulcr & Cognato 2010 syn. nov.); Terminalinus moluccanus (Browne, 1985) (= Xyleborus teminabani Browne, 1986 syn. nov.).