Evolution of endemism on a young tropical mountain.

Tropical mountains are hot spots of biodiversity and endemism, but the evolutionary origins of their unique biotas are poorly understood. In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities. Also, it is debated whether mountain endemics mostly originate from local lowland taxa, or from lineages that reach the mountain by long-range dispersal from cool localities elsewhere. Here we investigate the evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu in Sabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), and comprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shifts from lower to higher vegetation zones in this latter group were rare. These insights could improve forecasts of the likelihood of extinction and 'evolutionary rescue' in montane biodiversity hot spots under climate change scenarios.

Sexual selection predicts the persistence of populations within altered environments.

The effect of sexual selection on species persistence remains unclear. The cost of bearing ornaments or armaments might increase extinction risk, but sexual selection can also enhance the spread of beneficial alleles and increase the removal of deleterious alleles, potentially reducing extinction risk. Here we investigate the effect of sexual selection on species persistence in a community of 34 species of dung beetles across a gradient of environmental disturbance ranging from old growth forest to oil palm plantation. Horns are sexually selected traits used in contests between males, and we find that both horn presence and relative size are strongly positively associated with species persistence and abundance in altered habitats. Testes mass, an indicator of post-copulatory selection, is, however, negatively linked with the abundance of species within the most disturbed habitats. This study represents the first evidence from a field system of a population-level benefit from pre-copulatory sexual selection.

Selective­logging and oil palm: multitaxon impacts, biodiversity indicators, and trade­offs for conservation planning.

Strong global demand for tropical timber and agricultural products has driven large-scale logging and subsequent conversion of tropical forests. Given that the majority of tropical landscapes have been or will likely be logged, the protection of biodiversity within tropical forests thus depends on whether species can persist in these economically exploited lands, and if species cannot persist, whether we can protect enough primary forest from logging and conversion. However, our knowledge of the impact of logging and conversion on biodiversity is limited to a few taxa, often sampled in different locations with complex land-use histories, hampering attempts to plan cost-effective conservation strategies and to draw conclusions across taxa. Spanning a land-use gradient of primary forest, once- and twice-logged forests, and oil palm plantations, we used traditional sampling and DNA metabarcoding to compile an extensive data set in Sabah, Malaysian Borneo for nine vertebrate and invertebrate taxa to quantify the biological impacts of logging and oil palm, develop cost-effective methods of protecting biodiversity, and examine whether there is congruence in response among taxa. Logged forests retained high species richness, including, on average, 70% of species found in primary forest. In contrast, conversion to oil palm dramatically reduces species richness, with significantly fewer primary-forest species than found on logged forest transects for seven taxa. Using a systematic conservation planning analysis, we show that efficient protection of primary-forest species is achieved with land portfolios that include a large proportion of logged-forest plots. Protecting logged forests is thus a cost-effective method of protecting an ecologically and taxonomically diverse range of species, particularly when conservation budgets are limited. Six indicator groups (birds, leaf-litter ants, beetles, aerial hymenopterans, flies, and true bugs) proved to be consistently good predictors of the response of the other taxa to logging and oil palm. Our results confidently establish the high conservation value of logged forests and the low value of oil palm. Cross-taxon congruence in responses to disturbance also suggests that the practice of focusing on key indicator taxa yields important information of general biodiversity in studies of logging and oil palm.

An account on some katydids of the tribes Agraeciini (Conocephalinae) and Meconematini (Meconematinae) from the highlands of western Sabah.

Based on recent field sampling in the highlands of western Sabah, a new species of Depressacca Ingrisch, 1998 (Conocephalinae: Agraeciini) is described from Tenompok, Depressacca macrolima sp. nov., that can be easily distinguish from two other known congeners by the presence of numerous large and falcate spines on the legs numerous large and falcate spines on its legs. Based on the new material, we also document here the live images and/or new locality records for other katydids of the tribes Agraeciini and Meconematini: Bispinolakis longicauda Ingrisch, 1998, Palaeoagraecia philippina (Karny, 1926) and Salomona borneensis Willemse, 1959; Alloteratura (Meconemopsis) longa Gorochov, 2008, Borneratura kinabaluana (Bey-Bienko, 1971) and Rhinoteratura pulchra Gorochov, 2008.

New species of the elusive crickets from the genus Pendleburyella Chopard, 1969 (Gryllidae, Pentacentrinae) from Sabah, Borneo.

Only one species of Pendleburyella Chopard, 1969 (Gryllidae, Pentacentrinae) was previously known to occur in Borneo: Pendleburyella eirmosa Tan, Muhammad & Wahab, 2023 from Brunei Darussalam. Here, two additional new species of crickets from the genus Pendleburyella are described from the highlands of Sabah, Borneo: Pendleburyella eremita sp. nov. from Bukit Hampuan and Pendleburyella nimba sp. nov. from Mount Trus Madi. In total, six species of Pendleburyella are currently known, three from Borneo and three from Malay Peninsula. It is likely that many more species are awaiting discovery owing to its cryptic morphology and elusive nature.

A taxonomic review of Odontogryllodes Chopard, 1969 (Gryllidae: Landrevinae).

The taxonomy of the crickets from the genus Odontogryllodes Chopard, 1969 is reviewed. Two species new to science are described here, one from Peninsular Malaysia (part of Malay Peninsula) and another from East Malaysia (part of Borneo): Odontogryllodes undatus Tan, Muhammad & Abdullah sp. nov. from Panti Forest Reserve and Odontogryllodes magnus Tan, Japir & Chung sp. nov. from Tenompok Forest Reserve, respectively. We also present an updated key to the species of Odontogryllodes. In total, nine species are currently known.

New species of Itara (Orthoptera: Grylloidea: Itarinae) and descriptions of calling songs from Mindanao and Sabah.

A new species of Itara (Phormincter) is described from Mindanao in the Philippines: Itara (Phormincter) mindanao Tan, Grumo, Gono & Bahoy, sp. nov. This represents the first record of this subgenus in the Philippines, having previously known only from Borneo, Java, Malay Peninsula and Sumatra; as well as only the second species of Itara known from the Philippines and the first from Mindanao Island. The male calling song of the holotype was also recorded and is described here. Additionally, the male calling song of another congener, Itara (Singitara) singularis Gorochov, 1997 from Sabah, is described here. A new species of Itara (Bornitara) is also described from Sabah in Borneo: Itara (Bornitara) tenompok Tan, Japir & Chung, sp. nov.

Tropical beetles more sensitive to impacts are less likely to be known to science.

Insects are posited to be declining globally. This is particularly pertinent in tropical forests, which exhibit both the highest levels of biodiversity and the highest rates of biodiversity loss. However, for the hyper-diverse tropical insects there are scant data available to evidence declines. Understanding tropical insect diversity and its response to environmental change has therefore become a challenge, but it is estimated that 80% of tropical insect species remain undescribed1. Insect biodiversity predictions are based mostly on well-studied taxa and extrapolated to other groups, but no one knows whether resilience to environmental change varies between undescribed and described species. Here, we collected staphylinid beetles from unlogged and logged tropical forests in Borneo and investigated their responses to environmental change. Out of 252 morphospecies collected, 76% were undescribed. Undescribed species showed higher community turnover, reduced abundance and decreased probability of occurrence in logged forests. Thus the unknown components of tropical insect biodiversity are likely more impacted by human-induced environmental change. If these patterns are widespread, how accurate will assessments of insect declines in the tropics be?

Towards a better future for DNA barcoding: Evaluating monophyly- and distance-based species identification using COI gene fragments of Dacini fruit flies.

The utility of a universal DNA 'barcode' fragment (658 base pairs of the Cytochrome C Oxidase I [COI] gene) has been established as a useful tool for species identification, and widely criticized as one for understanding the evolutionary history of a group. Large amounts of COI sequence data have been produced that hold promise for rapid species identification, for example, for biosecurity. The fruit fly tribe Dacini holds about a thousand species, of which 80 are pests of economic concern. We generated a COI reference library for 265 species of Dacini containing 5601 sequences that span most of the COI gene using circular consensus sequencing. We compared distance metrics versus monophyly assessments for species identification and although we found a 'soft' barcode gap around 2% pairwise distance, the exceptions to this rule dictate that a monophyly assessment is the only reliable method for species identification. We found that all fragments regularly used for Dacini fruit fly identification >450 base pairs long provide similar resolution. 11.3% of the species in our dataset were non-monophyletic in a COI tree, which is mostly due to species complexes. We conclude with recommendations for the future generation and use of COI libraries. We revise the generic assignment of Dacus transversus stat. rev. Hardy 1982, and Dacus perpusillus stat. rev. Drew 1971 and we establish Dacus maculipterus White 1998 syn. nov. as a junior synonym of Dacus satanas Liang et al. 1993.

Notes on the Eneopterinae (Orthoptera, Grylloidea, Gryllidae) from eastern Sabah.

Based on material collected during recent fieldwork in eastern Sabah, the males of Nisitrus danum Robillard & Tan and Cardiodactylus variegatus Gorochov & Robillard are described for the first time, along with their calling songs. New locality records of N. danum, N. vittatus (Haan), Falcerminthus sandakan (Tan et al.), Cardiodactylus borneoe Robillard & Gorochov and C. variegatus are also presented. New material of Nisitrus species-N. danum and N. vittatus-allowed us to compare these syntopic species.

Contribution to the taxonomy of Uvarovia (Orthoptera: Chorotypidae: Mnesicleinae) from Borneo and Malay Peninsula.

Mnesicleinae is a little-known subfamily of Chorotypidae and consists of 19 genera distributed throughout the Malay Archipelago, including Uvarovia Bolvar, 1930. For many species from this subfamily, nearly nothing is known after their original descriptions. Based on new materials from recent surveys, we were able to examine specimens from two species: Uvarovia longipennis Bolvar, 1930 from Malay Peninsula (also type species for genus) and Uvarovia gracilipes Bolvar, 1931 from Borneo. Only female specimens were known for the two species. Here, we describe for the first time males specimens of Uvarovia longipennis and Uvarovia gracilipes. We also present an updated key to species of Uvarovia and a key to genera of Mnesicleinae from Borneo and Malay Peninsula.

A review of the genus Monseremus Ingrisch, 2018 (Orthoptera, Stenopelmatoidea, Gryllacrididae) from Borneo.

We review the taxonomy of the gryllacridids from a small genus Monseremus Ingrisch, 2018. Monseremus bellus (Tan Wahab, 2018) comb. nov., previously described from Brunei Darussalam before the description of Monseremus, is now added as a second known species in this genus. From a recent field trip, we also added new locality record for the type species Monseremus appendiculatus Ingrisch, 2018. First described from Mount Kinabalu in western Sabah, this species has now been reported also in Mount Silam in eastern Sabah. Males of the type species were also collected for the first time and are described here. Lastly, we provide a dichotomous key to separate these two species.

New taxa and notes on bark and bush crickets (Orthoptera, Grylloidea, Gryllidae, Landrevinae and Podoscirtinae) from Sabah.

From the eastern parts of Sabah, four new species of crickets are described, two of which are from the subfamily Landrevinae and two from the subfamily Podoscirtinae: Duolandrevus (Duolandrevus) nobilis sp. nov. and Odontogryllodes spinifer sp. nov.; and Brevimunda trilineata sp. nov. and Varitrella (Cantotrella) tabin sp. nov., respectively. We also describe the calling songs for three species: Duolandrevus (Bejorama) lambir Gorochov, 2017, Duolandrevus (Duolandrevus) nobilis sp. nov. and Varitrella (Cantotrella) tabin sp. nov. A new locality record (Sabah, Sepilok) for Duolandrevus (Bejorama) lambir Gorochov, 2017, previously known from western Borneo (Sarawak, Lambir Hill and Brunei Darussalam, Kuala Belalong), was also reported.

Taxonomy and bioacoustics of some katydids of the tribes Meconematini and Phisidini (Orthoptera, Tettigoniidae, Meconematinae) from eastern Sabah.

A new species of Meconematini is described from Tabin Wildlife Reserve in eastern Sabah: Cercoteratura repens sp. nov. This is the first report of the genus Cercoteratura in Sabah. Two species of Phisidini, Carliphisis acutipennis (Carl, 1908) and Neophisis (Indophisis) longipennis Jin, 1992, are reported in eastern Sabah for the first time. The calling song of Neophisis (Indophisis) longipennis with a near-complete ultrasonic spectrum is also described.

Taxonomy and bioacoustics of scaly crickets (Orthoptera, Mogoplistidae, Mogoplistinae) from Borneo and Singapore.

A species of scaly cricket is described here: Ornebius lupus sp. nov. from the mangrove forests in Singapore. Ornebius pullus Ingrisch, 2006 is recorded in eastern Sabah for the first time. The calling songs of Cycloptiloides bimaculatus Tan et al., 2021 and Ornebius pullus from Sabah are described. We also revise the diagnosis of Ectatoderus nigrofasciatus Tan et al., 2021 from Brunei Darussalam.

Oil palm expansion increases the vectorial capacity of dengue vectors in Malaysian Borneo.

Changes in land-use and the associated shifts in environmental conditions can have large effects on the transmission and emergence of mosquito-borne disease. Mosquito-borne disease are particularly sensitive to these changes because mosquito growth, reproduction, survival and susceptibility to infection are all thermally sensitive traits, and land use change dramatically alters local microclimate. Predicting disease transmission under environmental change is increasingly critical for targeting mosquito-borne disease control and for identifying hotspots of disease emergence. Mechanistic models offer a powerful tool for improving these predictions. However, these approaches are limited by the quality and scale of temperature data and the thermal response curves that underlie predictions. Here, we used fine-scale temperature monitoring and a combination of empirical, laboratory and temperature-dependent estimates to estimate the vectorial capacity of Aedes albopictus mosquitoes across a tropical forest-oil palm plantation conversion gradient in Malaysian Borneo. We found that fine-scale differences in temperature between logged forest and oil palm plantation sites were not sufficient to produce differences in temperature-dependent demographic trait estimates using published thermal performance curves. However, when measured under field conditions a key parameter, adult abundance, differed significantly between land-use types, resulting in estimates of vectorial capacity that were 1.5 times higher in plantations than in forests. The prediction that oil palm plantations would support mosquito populations with higher vectorial capacity was robust to uncertainties in our adult survival estimates. These results provide a mechanistic basis for understanding the effects of forest conversion to agriculture on mosquito-borne disease risk, and a framework for interpreting emergent relationships between land-use and disease transmission. As the burden of Ae. albopictus-vectored diseases, such as dengue virus, increases globally and rising demand for palm oil products drives continued expansion of plantations, these findings have important implications for conservation, land management and public health policy at the global scale.

Spiky pygmy devils: revision of the genus Discotettix (Orthoptera: Tetrigidae) and synonymy of Discotettiginae with Scelimeninae.

Spiky pygmy devils (Tetrigidae: Discotettiginae) are, because of the spiky pronotal projections and widened subapical antennal segments, among the most unique pygmy grasshoppers in Southeast (SE) Asia. The taxonomy of the group was unclear in the past, so this study brings a taxonomic and biographical review of the genus Discotettix Costa, 1864. New terminology of the pronotal projections is proposed for Scelimeninae. All valid species hitherto included in the genus are redescribed; a new genus is established for Discotettix shelfordi Hancock, 1907, Disconius Skejo, Pushkar et Tumbrinck gen. n., so a new combination is established for the species (Disconius shelfordi comb. n.). New synonymy is established: Discotettix selysi Bolívar, 1887 = Discotettix selangori Mahmood, Idris et Salmah, 2007 syn. n. Three new species are described and a key to Discotettix species is provided. The genus now includes seven species (1) Discotettix aruanus Skejo, Pushkar et Tumbrinck sp. n. from Aru; (2) D. belzebuth (Serville, 1838) from Borneo; (3) D. doriae Bolívar, 1898 stat. resurr. from the Mentawai islands; (4) D. kirscheyi Skejo, Pushkar, Tumbrinck et Tan sp. n. from Northeast (NE) Borneo; (5) D. scabridus (Stål, 1877) endemic to Mindanao and Samar; (6) D. selysi Bolívar, 1887 from Sumatra and peninsular Malaysia; (7) D. sumatrensis Skejo, Pushkar et Tumbrinck sp. n. endemic to southern Sumatra. Moreover, Discotettix is again subdivided into two subgenera: Mnesarchus Stål, 1877 stat. resurr. (D. scabridus) and nominotypical one (other species). Widened antennal segments are the only character common to all Discotettiginae genera, but this trait does not have great taxonomic importance, as it is homoplastic, meaning that it appeared in distant Tetrigidae groups independently. Discotettix is herewith transferred to the subfamily Scelimeninae and accordingly, the subfamily Discotettiginae Hancock, 1907 syn. n. becomes a junior synonym of the subfamily Scelimeninae Bolívar, 1887. The tribe Discotettigini stat. resurr., on the other hand, gathers corticolous genera of the Scelimeninae (Austrohancockia Günther, 1938, Bidentatettix Zheng, 1992, Disconius gen. n. Discotettix, Eufalconius Günther, 1938, Gibbotettix Zheng, 1992, Paragavialidium Zheng, 1994, Gavialidium Saussure, 1862, and Tegotettix Hancock, 1913), while the tribe Scelimenini becomes restricted to amphibious taxa. All taxa are described and amply depicted with both museum specimens and in situ photographs. An identification key is provided. The morphology and function of widened antennae in Discotettigini are discussed.

New species and taxonomic notes of scaly crickets (Orthoptera: Mogoplistidae: Mogoplistinae) from Borneo.

Recent orthopteran surveys in the hyper-diverse Borneo, i.e., Brunei Darussalam and Sandakan in Sabah, allow us to review the scaly crickets from the subfamily Mogoplistinae there. We discover and describe the male, as well as formally naming Cycloptiloides bimaculata Tan, Japir Chung, sp. nov. from Sandakan. This species was previously described as sp. 1 in a comprehensive revision by Ingrisch (2006) but only the females were known. We also describe Ectatoderus nigrofasciatus Tan Wahab, sp. nov. from Brunei Darussalam. New locality records are reported for Apterornebius kinabalu Ingrisch, 2006 in Sandakan (Sabah) and Ornebius pullus Ingrisch, 2006 in Belait District (Brunei).

Dung beetles as samplers of mammals in Malaysian Borneo-a test of high throughput metabarcoding of iDNA.

Invertebrate-derived DNA (iDNA) sampling in biodiversity surveys is becoming increasingly widespread, with most terrestrial studies relying on DNA derived from the gut contents of blood-feeding invertebrates, such as leeches and mosquitoes. Dung beetles (superfamily Scarabaeoidea) primarily feed on the faecal matter of terrestrial vertebrates and offer several potential benefits over blood-feeding invertebrates as samplers of vertebrate DNA. Importantly, these beetles can be easily captured in large numbers using simple, inexpensive baited traps, are globally distributed, and occur in a wide range of habitats. To build on the few existing studies demonstrating the potential of dung beetles as sources of mammalian DNA, we subjected the large-bodied, Bornean dung beetle (Catharsius renaudpauliani) to a controlled feeding experiment. We analysed DNA from gut contents at different times after feeding using qPCR techniques. Here, we first describe the window of DNA persistence within a dung beetle digestive tract. We found that the ability to successfully amplify cattle DNA decayed over relatively short time periods, with DNA copy number decreasing by two orders of magnitude in just 6 h. In addition, we sampled communities of dung beetles from a lowland tropical rainforest in Sabah, Malaysia, in order to test whether it is possible to identify vertebrate sequences from dung beetle iDNA. We sequenced both the gut contents from large dung beetle species, as well as whole communities of smaller beetles. We successfully identified six mammalian species from our samples, including the bearded pig (Sus barbatus) and the sambar deer (Rusa unicolor)-both vulnerable species on the IUCN red list. Our results represent the first use of dung beetle iDNA to sample Southeast Asian vertebrate fauna, and highlight the potential for dung beetle iDNA to be used in future biodiversity monitoring surveys.

New taxa of crickets (Orthoptera: Grylloidea: Phaloriinae, Phalangopsinae, Itarinae and Podoscirtinae) from Borneo (Brunei Darussalam and Sandakan).

Three new species were described from Borneo: Itara (Bornitara) spinosa sp. nov. and Aphonoides duri sp. nov. from Brunei and Varitrella (Cantotrella) suikei sp. nov. from Sandakan in Sabah. We describe the call of Varitrella (Cantotrella) suikei sp. nov. In addition to the new species descriptions, we also report new locality records of other recently discovered species: Borneloria spinosa Gorochov, 2018 in Belait (Brunei Darussalam), species of Anemozara Gorochov, 2014 in Brunei Darussalam and Terrozacla borneo Gorochov, 2014 in Belait.