Northeastern Borneo Research Articles

Maligay: An Iconic Tausug Traditional Token for Pagtammat in the Sulu Archipelago

The Tausug reside in Lupah Sug (Sulu) and even in Northeastern Borneo, including parts of Indonesia and Malaysia. Historically, they were governed under the Sulu Sultanate. Today, the Tausug maintain a strong connection to their heritage, including the tradition of Pagtammat, using Maligay as an example of a valued cultural practice in rural communities in Sulu, Philippines. Maligay Pagtammat symbolizes the completion of Quranic studies by children, reflecting a strong attachment to traditional learning methods and the importance of Islamic education. It is largely unknown outside the Tausug community, particularly in Luzon and Visayas, due to limited available literature. Hence, this study explores Maligay Pagtammat among Tausug families in the municipalities of Parang, Panglima Estino, and Panamao in Sulu. Through participant observation and interviews with eight participants, all residents of the three localities with first-hand experience of the practice, descriptive thematic analysis of the data revealed the cultural significance, educational practices, and community values linked to Maligay Pagtammat among Tausug families. Despite challenges such as poverty and pastoral lifestyles, parents value Islamic education and express appreciation through this tradition. The ceremony involves extensive preparations, a procession, epic narratives, and a communal meal. Findings highlight the cultural and educational practices of Tausug families in rural Sulu, showcasing their resilience in preserving traditions amidst modernization. This study contributes to understanding Tausug identity and community cohesion through cultural practices.

Diurnal Cycle and Dipolar Pattern of Precipitation over Borneo during an MJO Event: Lee Convergence and Offshore Propagation

Abstract Surface precipitation anomalies over Maritime Continent islands typically lead oceanic precipitation by a week in the form of dipolar pattern before the arrival of Madden–Julian oscillation (MJO) convective phase. The authors study this dipolar pattern over Borneo during the boreal winter MJO event in January–February 2017 using cloud-permitting modeling, observation, and reanalysis datasets. The diurnal cycles of precipitation are analyzed during the local growing and decaying stages of this MJO event. Both the observation and simulation show positive precipitation anomaly over southwestern Borneo and negative anomaly over northeastern Borneo associated with the MJO easterly in the growing stage, whereas the pattern reverses in the decaying stage. Due to relatively high terrain, the low-level flows over Borneo split near the topography on the diurnal time scale. During the late afternoon and night (1700–2000 local solar time), the splitting-flow-induced wake vortices and thermally driven sea breezes tend to converge at the leeside, both contributing to leeward convergence and precipitation, which peaks at midnight. Subsequent offshore propagation during midnight and early morning develops from the leeward inland convection, and propagates northwestwards in the growing stage over west Borneo, and eastward in the decaying stage over east Borneo. Offshore propagation lasts until the next noon when sea breezes and island convection initiate. The timing and location of the offshore propagation suggest that it is not an independent convective mode. Instead, it is tied to the dipolar distribution of island precipitation modulated by the MJO.

Mantle Flow Patterns Beneath the Junction of Multiple Subduction Systems Between the Pacific and Tethys Domains, SE Asia: Constraints From SKS‐Wave Splitting Measurements

AbstractThe region around the Celebes Sea, SE Asia, is evolving within a convergent tectonic environment involving the Pacific plate to the east and the Indian‐Australian plate to the south. It is arguably one of the most tectonically complex regions in the world and serves as an ideal setting to study dynamic interactions between the Pacific and Tethys tectonic domains. The issue of which subducting plate plays a leading role in governing the regional mantle flow is not well understood. Mantle flow can be characterized by seismic anisotropy observations, providing clues for understanding regional tectonics. We conducted SKS‐wave splitting analysis by using data from seven seismic stations located around the Celebes Sea. Our results, when combined with previous observations, suggest the presence of various types of mantle flow in this area, including (a) corner flow in the mantle wedge above the westward‐subducting Molucca Sea (Sangihe) slab, (b) two‐layer anisotropy related to the eastward‐subducting Molucca Sea (Halmahera) slab, (c) deflected flow due to proximity to the Sangihe slab's edges, (d) trench‐normal mantle flow beneath southeastern Borneo due to the subduction of the Indian‐Australian plate, and (e) Northwest Borneo‐Palawan trough‐parallel mantle flow beneath northeastern Borneo. Various types of mantle flow indicate that the dynamic interactions of adjacent subduction zones played crucial roles in influencing the regional upper mantle dynamics between the Tethys and western Pacific domains since the breakup of the Gondwana supercontinent in the Mesozoic.

How index selection, compression, and recording schedule impact the description of ecological soundscapes.

Acoustic indices derived from environmental soundscape recordings are being used to monitor ecosystem health and vocal animal biodiversity. Soundscape data can quickly become very expensive and difficult to manage, so data compression or temporal down‐sampling are sometimes employed to reduce data storage and transmission costs. These parameters vary widely between experiments, with the consequences of this variation remaining mostly unknown.We analyse field recordings from North‐Eastern Borneo across a gradient of historical land use. We quantify the impact of experimental parameters (MP3 compression, recording length and temporal subsetting) on soundscape descriptors (Analytical Indices and a convolutional neural net derived AudioSet Fingerprint). Both descriptor types were tested for their robustness to parameter alteration and their usability in a soundscape classification task.We find that compression and recording length both drive considerable variation in calculated index values. However, we find that the effects of this variation and temporal subsetting on the performance of classification models is minor: performance is much more strongly determined by acoustic index choice, with Audioset fingerprinting offering substantially greater (12%–16%) levels of classifier accuracy, precision and recall.We advise using the AudioSet Fingerprint in soundscape analysis, finding superior and consistent performance even on small pools of data. If data storage is a bottleneck to a study, we recommend Variable Bit Rate encoded compression (quality = 0) to reduce file size to 23% file size without affecting most Analytical Index values. The AudioSet Fingerprint can be compressed further to a Constant Bit Rate encoding of 64 kb/s (8% file size) without any detectable effect. These recommendations allow the efficient use of restricted data storage whilst permitting comparability of results between different studies.

Taxonomic review of Xenorhyncocoris Miller (Heteroptera: Reduviidae: Ectrichodiinae), with description of X. attractivus sp. nov. and notes on sexual dimorphism of the genus

The enigmatic millipede assassin bug genus Xenorhyncocoris Miller, 1938 is revised. Previously known species, X. caraboides Miller, 1938, X. princeps Miller, 1949 and X. schoenitzeri Putshkov & Bérenger, 1999, are diagnosed and photographed. A new species, X. attractivus sp. nov., is described based on male and female specimens from northeastern Borneo. The male of Xenorhyncocoris is reported for the first time, revealing the extreme sexual dimorphism present in the genus. The diagnosis of Xenorhyncocoris is extended in order to make it applicable to the new discovery, and a female-based key to species of the genus is updated. Relationships among Xenorhyncocoris and Vilius Stål, 1863, Neozirta Distant, 1919 and Schottus Distant, 1902 are briefly discussed.

Fungal communities in bat guano, speleothem surfaces, and cavern water in Madai cave, Northern Borneo (Malaysia)

ABSTRACT The island of Borneo is a global biodiversity hotspot. However, its limestone caves are one of its least-studied ecosystems. We report for the first time the fungal species richness, diversity and abundance from Madai cave, situated in north-eastern Borneo. Environmental samples from inside the cave environment were collected (guano, speleothem, and cavern water) via opportunistic sampling. The dilution method was performed for isolation of fungi. Morphological characterisation and molecular analysis of the ITS region were utilised for the identification of isolates. Fifty-five pure cultures of fungi were attained, comprising 32 species from 15 genera, eight orders, and two divisions, Ascomycota and Basidiomycota. Ascomycetes dominated the fungal composition, accounting for 53 (96%) out of 55 total isolates. Penicillium spp. accounted for more than 47.1% of fungal abundance in all sample types. However, Aspergillus spp. had the highest occurrence rate, being isolated from all environmental samples except one. Purpureocillium lilacinum was isolated most frequently, appearing in five separate samples across all three substrates. Annulohypoxylon nitens, Ganoderma australe, Pyrrhoderma noxium, and Xylaria feejeensis were discovered and reported for the first time from the cave environment. This study provides additional data for further research on the mycoflora of Sabah’s various ecosystems, especially limestone caves.

Interactions in multi-pattern M\xfcllerian communities support origins of new patterns, false structures, imperfect resemblance and mimetic sexual dimorphism

Mimicry is a hot spot of evolutionary research, but de novo origins of aposematic patterns, the persistence of multiple patterns in Müllerian communities, and the persistence of imperfect mimics still need to be investigated. Local mimetic assemblages can contain up to a hundred of species, their structure can be a result of multiple dispersal events, and the gradual build-up of the communities. Here, we investigate the structure of lowland and mountain mimetic communities of net-winged beetles by sampling the Crocker Range in north-eastern Borneo and neighbouring regions. The local endemics evolved from the Bornean lowland fauna which is highly endemic at the species level. We inferred that metriorrhynchine net-winged beetles evolved in high elevations yellow/black and reticulate aposematic high-contrast signals from a widespread low-contrast brown/black pattern. As the mountain range is ~ 6 million years old, and these patterns do not occur elsewhere, we assume their in situ origins. We demonstrate that a signal with increased internal contrast can evolve de novo in a mimetic community and can persist despite its low frequency. Additionally, a similar aposematic signal evolves from different structures and its similarity is imperfect. The community with multiple patterns sets conditions for the evolution of aposematic sexual dimorphism as demonstrated by the yellow/black male and reticulate female pattern of Micronychus pardus. These insights elucidate the complex character of the evolution of mimetic signalling in the dynamically diversifying biota of high tropical mountains.

Imaging spectroscopy reveals the effects of topography and logging on the leaf chemistry of tropical forest canopy trees.

Logging, pervasive across the lowland tropics, affects millions of hectares of forest, yet its influence on nutrient cycling remains poorly understood. One hypothesis is that logging influences phosphorus (P) cycling, because this scarce nutrient is removed in extracted timber and eroded soil, leading to shifts in ecosystem functioning and community composition. However, testing this is challenging because P varies within landscapes as a function of geology, topography and climate. Superimposed upon these trends are compositional changes in logged forests, with species with more acquisitive traits, characterized by higher foliar P concentrations, more dominant. It is difficult to resolve these patterns using traditional field approaches alone. Here, we use airborne light detection and ranging‐guided hyperspectral imagery to map foliar nutrient (i.e. P, nitrogen [N]) concentrations, calibrated using field measured traits, over 400 km2 of northeastern Borneo, including a landscape‐level disturbance gradient spanning old‐growth to repeatedly logged forests. The maps reveal that canopy foliar P and N concentrations decrease with elevation. These relationships were not identified using traditional field measurements of leaf and soil nutrients. After controlling for topography, canopy foliar nutrient concentrations were lower in logged forest than in old‐growth areas, reflecting decreased nutrient availability. However, foliar nutrient concentrations and specific leaf area were greatest in relatively short patches in logged areas, reflecting a shift in composition to pioneer species with acquisitive traits. N:P ratio increased in logged forest, suggesting reduced soil P availability through disturbance. Through the first landscape scale assessment of how functional leaf traits change in response to logging, we find that differences from old‐growth forest become more pronounced as logged forests increase in stature over time, suggesting exacerbated phosphorus limitation as forests recover.

Pliocene corals from the Togopi Formation of the Dent Peninsula, Sabah, northeastern Borneo, Malaysia

Saw, J.V.M., Hunter, A.W., Johnson, K.G. & Abdul Rahman, A.H.B., November 2018. Pliocene corals from the Togopi Formation of the Dent Peninsula, Sabah, northeastern Borneo, Malaysia. Alcheringa 43, 291–319. ISSN 0311-5518The palaeobiology of the Malay Archipelago region remains poorly documented, despite its present-day significance as a modern global marine biodiversity hotspot. The Togopi Formation of the Dent Peninsula, situated in Borneo on the western Sulu Sea and eastern coast of Sabah, Malaysia, preserves Plio-Pleistocene sedimentary sequences interpreted to represent localized transgressive episodes, and which have a relatively high coral diversity. Fossil corals were sampled from three available quarries on the Dent Peninsula, the sediments of which have been previously dated as 4.5–3.4 Ma in age based on foraminiferal data and radiometric analyses. These Pliocene corals are identified here based on their macromorphology, micromorphology and microstructural characteristics. In total, this study describes 28 fossil coral taxa, with 16 genera recognized and 22 taxa identified to species level, 21 of which can be confidently assigned to extant species. These new data have resulted in revised stratigraphic ranges for eight of these species. As the most comprehensive systematic survey of corals from the Pliocene of the Indo-Pacific to date, this study indicates a high diversity of corals on the margin of the Sabah Sea, Borneo, at this time, including taxa found today, thus casting doubt on the local impact of the Plio-Pleistocene extinction previously reported from faunal analyses of the central Indo-Pacific.Jasmin V.M. Saw [varnmay@yahoo.com] Department of Petroleum Geosciences, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia; Aaron W. Hunter* [awh31@cam.ac.uk] Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK; Kenneth G. Johnson [k.johnson@nhm.ac.uk] Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK; Abdul Hadi B Abdul Rahman [hadi_rahman@utp.edu.my] Department of Petroleum Geosciences, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia. *Also affiliated with: School of Earth Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.

Lithostratigraphy of Tabul Formation and Onshore Geology of Nunukan Island, North Kalimantan

Nunukan Island is located in Northeast Kalimantan Basin, one of prolific basin in western Indonesia. However, this island lies in northern verge of the basin and hydrocarbon exploration were limited before the 1940s. No detail geological fieldworks has been published. This paper attempts to share geological information obtained from few accessible outcrops, particularly from the western part of the island where previous oil drilling were carried out. Most of the island have been built by Tabul Formation, which was also the main objective of reservoir for hydrocarbon exploration. It is composed of claystones, siltstones, and sandstones interbeds, deposited in transitional environment during Late Miocene. They exhibit coarsening upward sequence, the lower part composed of heterolitic sandstones deposited in tidal flats, and the upper part composed of arkosic sandstones deposited in distributary channels and mouthbars. The eastern coastal strip was constructed by Tarakan conglomerates, which have been deposited in fluvio-deltaic environment in Pliocene, unconformably over the Tabul clastics. Those Neogene deposition of paleo-Simengaris Delta apparently deformed and inverted in Plio-Pleistocene, contemporaneously with basaltic volcanism which spread widely over northeastern Borneo, which also observed in the northern half of the Nunukan Island

Regional Conservation Implications of Green Turtle (Chelonia mydas) Genetic Stock Composition in China

Abstract Sea turtles are globally endangered and face anthropogenic threats, such as direct harvest, bycatch, and habitat degradation. Genetic studies help identify connectivity between nesting and foraging grounds for conservation and management. However, information on genetic stock composition of green turtles (Chelonia mydas) in the South China Region (including Hong Kong, Guangdong Province, and Taiwan) is severely limited. In this study, mixed stock analysis based on the 760-bp mitochondrial DNA (mtDNA) control region of green turtles (n = 110) revealed that the primary source rookeries in the Pacific contributing to foraging green turtle aggregations in the South China Region were Peninsular Malaysia, Yap in the Federated States of Micronesia, Aru of Indonesia, Sulu Sea, northeastern Borneo, Republic of Marshall Islands, Wan-an of Taiwan, and the central Ryukyu and Yaeyama of Japan. This study is the first to investigate and report the source nesting populations of a relatively large number of fora...

Spatio-temporal changes in rate of soil loss and erosion vulnerability of selected region in the tropical forests of Borneo during last three decades

An attempt has been made to analyze the spatial-temporal characteristics of soil erosion vulnerability and soil loss from the forested region in the north-eastern Borneo, Sarawak, Malaysia during the last three decades (1991–2015) using the revised universal soil loss equation (RUSLE) and geographical information systems (GIS). The components of RUSLE such as rainfall erosivity (R), soil erodibility (K), slope-length and steepness (LS), cover management (C) and conservation practice (P) factors were grouped into two categories by keeping one set as temporally changing and others as static. Among them the R and C factors are calculated for the years 1991, 2001 and 2015 whereas the K and LS factors are considered for the single time frame. Because of the forested nature of the study area, the P factor is kept constant for the whole analysis. The R factor and C factor is shown changes in values and its distribution over the years, which reflected in the final soil loss and erosion vulnerability map as a change in the rate of erosion and spatial domain. The analysis of three time slices has shown that the maximum value of the soil loss per unit area i.e. at erosion hotspots, is relatively similar throughout at around 1636 to 1744 t/ha/y. This is the result of maximum values of R factor and C factor i.e. high rainfall erosivity combined with lack of vegetation cover in those hotspots, which are generally steeply sloping terrain. The reclassification of annual soil loss map into erosion vulnerability zones indicated a major increase in the spatial spread of erosion vulnerability from the year 1991 to 2015 with a significant increase in the high and critical erosion areas from 2.3% (1991) to 31.5% (2015). In 1991, over 84% of the study area was under low erosion vulnerability class but by the year 2015 only 12% was under low erosion vulnerability class. Moreover, a dynamic nature in the erosion pattern was found from the year 1991 to 2015 with more linear areas of land associated with higher rate of soil loss and enhanced erosion vulnerability. The linearity in the spatial pattern is correlated with the development of logging roads and logging activities which has been confirmed by the extraction of exposed areas from satellite images of different years of analysis. The findings of the present study has quantified the changes in vegetation cover from dense, thick tropical forest to open mixed type landscapes which provide less protection against erosion and soil loss during the severe rainfall events which are characteristic of this tropical region.

Genomic phylogeography of the endemic Mountain Black‐eye of Borneo (Chlorocharis emiliae): montane and lowland populations differ in patterns of Pleistocene diversification

AbstractAimOur understanding of population diversification in the lowlands of Sundaland has improved substantially over the last 20 years through phylogeographical study, but we know almost nothing about population diversification in the mountains of the region. Here, we apply genomic analysis and habitat modelling to the phylogeography of Chlorocharis emiliae, the Mountain Black‐eye, an endemic montane bird of Borneo with a sky‐island distribution, to investigate the structure and interconnectivity of its populations. In the process, we consider factors driving population diversification in the mountains versus lowlands on the island, and how population structure of C. emiliae compares with structure of previously studied lowland species.LocationBorneo.MethodsUsing RAD‐seq, we produced thousands of SNPs in 25 individuals from five sky‐island populations of C. emiliae. These populations represent the species entire range across Borneo. Genetic structure and species tree analyses were applied to measure population relationships and connectivity. Ecological niche modelling was used to estimate habitat distributions during current and LGM time periods.ResultsWe identified slight to moderate genetic distinctiveness among all populations. Based on demographic models, isolation with migration was the main pattern of divergence, and the most admixture occurred among three populations in north‐eastern Borneo: Kinabalu, Trus Madi and Murud. The most divergent population, Pueh, in north‐western Borneo, has low genetic diversity and a small effective population size, is geographically isolated and has diverged in isolation without notable gene flow. These results, based on a large genomic dataset, contradict the evolutionary relationships identified in an earlier mitochondrial DNA study.Main conclusionsGenomic phylogeographical comparisons indicate that diversification among sky‐island populations of C. emiliae was driven largely by distance and historical habitat distribution, resulting in isolation but also some inter‐population gene flow. During Pleistocene glacial events, cooler temperatures would have caused montane forest to descend and spread, thereby increasing connectivity among sky‐island populations. However, despite increased montane habitat, the north‐western population of Pueh remained isolated. This montane pattern contrasts with phylogeographical patterns in the Bornean lowlands, where populations often display evidence of vicariance followed by secondary contact.

Lessons from Research for Sustainable Development and Conservation in Borneo

I present a brief synopsis of six key lessons provided by research on forest ecology and conservation, focusing particularly on the Malaysian state of Sabah in northeastern Borneo. These lessons are generalizable to other contexts, especially for tropical developing nations, where surviving forests are under growing pressures from a range of human activities.

Continental copepod biodiversity in North-Eastern Borneo, Malaysia

To obtain a relevant information on copepod biodiversity/distribution in continental Borneo water bodies in June 2011 about 30 different sites in Malaysian state Sabah were visited and more than 50 alcohol and formalin preserved samples in nine rivers, 10 ponds, and six near-road ditches and canals, rice fields and forest leaf litter environment were collected. In literature 16 copepod species were referred for Borneo and 10 other species for Kalimantan (Indonesean) states. After the Sabah sample analyses, the copepodspecies richnessin the Borneo island increased more than twice. The most abundant with species number genera were ranged as: Mesocyclops (13), Elaphoidella (6), Microcyclops (5), Eucyclops (4), Thermocyclops (4), Halicyclops (3) and Paracyclops (3). Species biodiversity in different sites plotted against type of water body and several environment parameters revealed significant positive correlations for number of species and both for depth and temperature in sampling site (Pearson non-parametric tests 0.6 and 0.5 respectively at p < 0.05). One way Kruscal-Walise dispersal analysis confirmed significant relationship between copepod biodiversity and water transparence/ turbidity (p < 0.05). The highest copepod biodiversity values were found in ponds (23 species), near road ditches (15), rivers with transparent water (12), lowland or swamp areas related with rivers (9). The lowest number of species were found in rivers with turbid water colored in orange with soil-erosive matter where the average number of copepod species (0.2 ± 0.08 species per site) was about 20 times less than in waters without silt particles (3.8 ± 2.8 species per site). This indicates a strong negative effect of soil erosion resulting water land-used activities and deforestation in the watershed on the biodiversity of aquatic organisms in Borneo. In one sub-urban population of Mesocyclops cf. thermocyclopoides, a trans-sexual mutation of female-sized but constructed as male armed with genicu late antennule organisms was found that possibly reflect a negative result of wide artificial hormone-based pesticide usage in this area. Keys for Harpacticoida species for Borneo and for Eucyclops species known for SEAsia, Australia and India are provided. Within practically each copepod genus studied in Borneo there are forms with problems on species identification by existing faunistic keys. This possibly indicates a necessity of new species description from this area in the nearest future.

Revision of the Oriental subfamily Heteropteryginae Kirby, 1896, with a re-arrangement of the family Heteropterygidae and the descriptions of five new species of Haaniella Kirby, 1904.(Phasmatodea: Areolatae: Heteropterygidae).

Revision of the Oriental subfamily Heteropteryginae Kirby, 1896, with a re-arrangement of the family Heteropterygidae and the descriptions of five new species of Haaniella Kirby, 1904.(Phasmatodea: Areolatae: Heteropterygidae).

Jellyfish-associated bacterial communities and bacterioplankton in Indonesian Marine lakes.

In the present study, we compared communities of bacteria in two jellyfish species (the 'golden' jellyfish Mastigias cf.papua and the box jellyfish Tripedalia cf.cystophora) and water in three marine lakes located in the Berau region of northeastern Borneo, Indonesia. Jellyfish-associated bacterial communities were compositionally distinct and less diverse than bacterioplankton communities. Alphaproteobacteria, Gammaproteobacteria, Synechococcophycidae and Flavobacteriia were the most abundant classes in water. Jellyfish-associated bacterial communities were dominated by OTUs assigned to the Gammaproteobacteria (family Endozoicimonaceae), Mollicutes, Spirochaetes and Alphaproteobacteria (orders Kiloniellales and Rhodobacterales). Mollicutes were mainly restricted to Mastigias whereas Spirochaetes and the order Kiloniellales were most abundant in Tripedalia hosts. The most abundant OTU overall in jellyfish hosts was assigned to the family Endozoicimonaceae and was highly similar to organisms in Genbank obtained from various hosts including an octocoral, bivalve and fish species. Other abundant OTUs included an OTU assigned to the order Entomoplasmatales and mainly found in Mastigias hosts and OTUs assigned to the Spirochaetes and order Kiloniellales and mainly found in Tripedalia hosts. The low sequence similarity of the Entomoplasmatales OTU to sequences in Genbank suggests that it may be a novel lineage inhabiting Mastigias and possibly restricted to marine lakes.

Congruence of microsatellite and mitochondrial DNA variation in acrobat ants (Crematogaster subgenus Decacrema, Formicidae: Myrmicinae) inhabiting Macaranga (Euphorbiaceae) myrmecophytes.

A previously reported mitochondrial DNA (mtDNA) phylogeny of Crematogaster (subgenus Decacrema) ants inhabiting Macaranga myrmecophytes indicated that the partners diversified synchronously and their specific association has been maintained for 20 million years. However, the mtDNA clades did not exactly match morphological species, probably owing to introgressive hybridization among younger species. In this study, we determined the congruence between nuclear simple sequence repeat (SSR, also called microsatellite) genotyping and mtDNA phylogeny to confirm the suitability of the mtDNA phylogeny for inferring the evolutionary history of Decacrema ants. Analyses of ant samples from Lambir Hills National park, northeastern Borneo, showed overall congruence between the SSR and mtDNA groupings, indicating that mtDNA markers are useful for delimiting species, at least at the local level. We also found overall high host-plant specificity of the SSR genotypes of Decacrema ants, consistent with the specificity based on the mtDNA phylogeny. Further, we detected cryptic genetic assemblages exhibiting high specificity toward particular plant species within a single mtDNA clade. This finding, which may be evidence for rapid ecological and genetic differentiation following a host shift, is a new insight into the previously suggested long-term codiversification of Decacrema ants and Macaranga plants.

Diversification of filter-feeding nudibranchs: two remarkable new species of Melibe (Opisthobranchia: Tethyiidae) from the tropical western Pacific

Two new species of the genus Melibe are described from the tropical western Pacific. Melibe colemani sp. nov. is described from northeastern Borneo, Malaysia. This species is transparent with a series of white interconnecting digestive gland ducts visible throughout the body. It is also characterized by having weakly denticulate jaws, highly ramified digestive gland tracks that extend throughout the body, and a reproductive system with an external nodular vaginal gland and a penis with a curved apex. Melibe coralophilia sp. nov., described from the Philippines and Malaysia, has a deep golden brown colour. The body is wide and densely covered with tubercles that form a mid-dorsal crest and cover the surface of the ‘cerata’. Internally, this species has a massive muscular buccal mass, jaws with a finely denticulate margin, tuberculate ganglia in the central nervous system and an expanded, rounded receptaculum seminis. Melibe coralophilia is associated with the scleractinean coral Porites sp. and the blue coral Heliopora coerulea although the nature of this association remains unknown. This species is also unusual in that the egg mass is carried on the right side of the body located posterior to the genital atrium and is found between the mantle and the foot. A morphological phylogeny suggests that M. colemani is most closely related to M. engeli Risbec, 1937, M. digitata Gosliner & Smith, 2003 and M. tuberculata Gosliner & Smith, 2003. Melibe coralophilia is a member of the Indo-Pacific clade of Melibe species, but its relationship to other taxa remains unresolved. Preliminary molecular data suggest a more complex relationship between Melibe species, but strongly support the notion that all of the species examined represent distinct lineages. The sister-group relationship of Tethys with Melibe is confirmed and the molecular phylogeny supports the monophyly of Melibe and Tethyiidae based on the combined molecular dataset.

Multilocus analysis of the evolutionary dynamics of rainforest bird populations in Southeast Asia

Sundaland has a dynamic geographic history because its landmasses were periodically interconnected when sea levels fell during glacial periods. Superimposed on this geographic dynamism were environmental changes related to climatic oscillations. To investigate how tropical taxa responded to such changes, we studied the divergence and demographic history of two co-distributed rainforest passerine species, Arachnothera longirostra and Malacocincla malaccensis. We sampled birds primarily from Borneo and the Malay Peninsula, which straddle the now-submerged Sunda shelf, and analysed multilocus DNA data with a variety of coalescent and gene genealogy methods. Cross-shelf divergence in both species occurred well before the last glacial maximum, i.e., before the most recent land connection. However, post-divergence gene flow occurred, and it was more pronounced in A. longirostra (a highly vagile nectarivore/insectivore) than in M. malaccensis (an understory insectivore). Despite current habitat continuity on Borneo, the population of M. malaccensis in northeastern Borneo is substantially divergent from that on the rest of the island. The NE population experienced dramatic demographic fluctuations, probably because of competition with the other population, which expanded from western Borneo after the mid-Pleistocene. In contrast, the Borneo population of A. longirostra has little structure and appears to have experienced demographic expansion 16 kya, long after it had diverged from the Malay Peninsula population (630-690 kya). Malay Peninsula populations of both species have remained relatively stable. Overall, the most recent glacial period was not the chief determinant of the evolutionary dynamics of our study species, and in this respect, they are different from temperate species.