Peninsular Malaysia Research Articles

Companion to R. H. Beddom's Handbook to the Ferns of British India, Ceylon and the Malay Peninsula

No Abstract.

Third List of Species and Genera of Indian Phanerogams not Included in J. D. Hooker's Flora of British India (Excluding Bangladesh, Burma, Ceylon, Malayan Peninsula and Pakistan)

Calder et al. (1926) presented the first list of Phancrogams not included in J.D. Hooker's Flora of British India and it covered a span of twenty six years between 1898-1924. Razi (1959) enumerated the second list of Indian Phanerogams supplementing Calder's list for the period from 1924 to 1950 and this again covered a period of twenty six years. The third list now presented by the authors spanned a period of twenty five years (1950-1975) and the plants enumerated is geographically delimited to India, Bhutan and Nepal. In the present list the authors have listed about 1000 taxa of Phanerogams added to the Indian flora supplementing the lists of Calder (1926) and Razi (1959). The countries Bhutan and Nepal are part of Himalayan region and for any study of Himalayan flora of India, it is necessary to understand the floristic elements of Nepal and Bhutan since many Himalayan elements occur in the contiguous territories of India, Bhutan and Nepal.

Genetic erosion in a tropical tree species demonstrates the need to conserve wide-ranging germplasm amid extreme habitat fragmentation

AbstractComparing the genetic diversity across different generations within tropical tree populations is an understudied topic. To assess the potential genetic consequences and conservation implications of contemporary disturbances, a population genomic study of Palaquium obovatum across age classes was undertaken. Trees and juveniles were sampled from ten different localities (eight in Singapore, two in Peninsular Malaysia) and subjected to double digest restriction-site associated DNA-sequencing (ddRAD-seq) to assess intergenerational genetic differences and investigate population structure in a hexaploid lineage. Genetic erosion, characterised by reduced heterozygosity, was found to have occurred in almost all wild populations over time, the exceptions being in one isolated coastal population and some areas with cultivated occurences. Population structure was highly localised with the number of genetically distinct populations usually following geographically separated districts, which indicates limitations in pollen and seed dispersal between fragments, possibly due to declines in the associated assemblage of dispersers. For this reason, the germplasm for conserving species diversity in degraded habitats and forest fragments should be selected from a wide range of wild populations across the landscape.

Green hydrogen prospects in Peninsular Malaysia: a techno-economic analysis via Monte Carlo simulations

According to Malaysia's National Energy Transition Roadmap, hydrogen is a critical component of the country's energy transition. However, there is a scarcity of hydrogen studies for Peninsular Malaysian states, which limits discussions on green hydrogen production. This study employs a Monte Carlo model to assess the economic and technical factors influencing the success of green hydrogen in Peninsular Malaysia. The study focuses on three target years: 2023, 2030, and 2050, representing various stages of technological development and market adoption. The levelized cost of hydrogen (LCOH) of a 1-MW Proton Exchange Membrane (PEM) electrolyzer system ranges from $5.39 to $10.97 per kg in 2023, highlighting early-stage challenges and uncertainties. A 6-MW PEM electrolyzer system could achieve an LCOH of $3.50 to $4.72 per kg by 2030, indicating better prospects. Because of technological advancements and cost reductions, a 20-MW PEM electrolyzer system could achieve an LCOH of $3.12 to $3.64 per kg in 2050. The findings indicate that the northern regions of Peninsular Malaysia have consistently low LCOH values due to favorable geographical conditions. Due to minor variations in solar capacity factors, uncertainty distributions in LCOH remain stable across different regions. Some states may face increased uncertainty, emphasizing the need for additional policy support mechanisms to mitigate risks associated with green hydrogen investments. The sensitivity analysis shows that key cost drivers are shifting, with early-stage electrolyzer investments dominating in 2023 and electricity prices becoming more important in 2030 and 2050. Future research could focus on optimizing green hydrogen systems for areas with underdeveloped green hydrogen industries. This study contributes to informed discussions about green hydrogen production by emphasizing the importance of tailored strategies that consider local conditions and highlighting the role of Peninsular Malaysia in the energy transition.

Spatiotemporal Characteristics and Rainfall Thresholds of Geological Landslide Disasters in ASEAN Countries

Drawing upon a comprehensive global database of landslides and utilizing high-resolution IMERG satellite precipitation data, this study investigates the spatial and temporal variations of landslide occurrences across the member states of the Association of Southeast Asian Nations (ASEAN). This study constructs a region-specific, graded warning system by formulating an average effective intensity–duration (I–D) rainfall threshold curve for each ASEAN member. Examination of 1747 landslide events spanning from 2006 to 2018 illustrates a significant association between the frequency of landslides in ASEAN regions and the latitudinal movement of local precipitation bands. Incidences of landslides hit their lowest in March and April, while a surge is observed from October to January, correlating with the highest mortality rates. Geographical hotspots for landslide activity, characterized by substantial annual rainfall and constrained landmasses, include the Philippine archipelago, Indonesia’s Java Island, and the Malay Peninsula, each experiencing an average of over 2.5 landslides annually. Fatalities accompany approximately 41.4% of ASEAN landslide events, with the Philippines and Indonesia registering the most substantial numbers. Myanmar stands out for the proportion of large-scale landslide incidents, with an average casualty rate of 10.89 deaths per landslide, significantly surpassing other countries in the region. The I–D rainfall threshold curves indicate that the Philippines experienced the highest precipitation levels before landslide initiation, whereas Myanmar has the threshold set at a considerably lower level.

Diversity and assemblage patterns of ladybirds (Coccinellidae) in different crop management practices in Peninsular Malaysia

Diversity and assemblage patterns of ladybirds (Coccinellidae) in different crop management practices in Peninsular Malaysia

The Issues and Challenges of Diversification Strategy in Multiple Industries: The Case of Kental Bina Sdn. Bhd.

A diversification strategy is one of the means to expand business among corporations, including Small and Medium Enterprises (SMEs). In Malaysia, many successful stories of SMEs’ diversification strategies permit others to follow in their footstep. The success of the strategy allows businesses to develop not only locally but also venture into the international market. However, various issues and challenges could be associated with diversification strategy implementation particularly among SMEs within multiple industries involved. Therefore, this study aims to discover the issues and challenges faced by Kental Bina Sdn. Bhd., one of the steadily growing diversified businesses in Northern Peninsular Malaysia. This study employed a few rounds of one-on-one interviews with the business owner as the key informant to meet the study objective. The recorded interview sessions are then transcribed and analyzed using thematic analysis through the Nvivo12 software. From the policy viewpoint, this study sheds light on the development of entrepreneurial training programs. The training program conducted by the relevant ministries and government agencies, including the Ministry of Entrepreneur and Cooperatives Development (MECD), Majlis Amanah Rakyat (MARA), SME Corporation (SMECorp.), and Tekun Nasional (TEKUN), needs to be specifically designed to address the issues and challenges of business diversification particularly among SMEs. For practical implication, this study helps to offer important information and inputs among other businesses, particularly SMEs, on what to expect when starting their diversification planning and strategy.

Feasibility Study of Solar-Powered Electric Vehicle Charging Infrastructure at Selected Petrol Stations in Malaysia

The transition from the conventional internal combustion engine (ICE) to electric vehicles (EV) are expected to result in higher total electricity demand in the country. With the introduction of more EVs into the market, the need for charging stations will grow, subsequently increasing power consumption. This research study aims to assess the potential of solar energy production at petrol stations in central region of Peninsular Malaysia and assess the feasibility of solar-powered petrol stations in meeting the energy demands of electric vehicles. 10 samples of existing petrol stations are selected to install a solar-powered DC charging station as a case study. To study their energy consumption, 90kW DC charger was evaluated. The design of the PV systems for the petrol stations was done by using the PVsyst simulation software. As a result, it is found that 90% of the designed PV systems are able to generate enough energy to meet the estimated annual energy consumption of the 90kW DC charging system. The results also showed that the cost to install the solar-powered charging system for both power ratings can be recouped in less than 2 years. Overall, this research study offers valuable insights for addressing the rising energy consumption resulting from the increased penetration of electric vehicles in the future. Additionally, the implementation of solar-powered charging infrastructure aligns with the country’s renewable energy objectives and efforts to reduce greenhouse gas emissions. However, the assessment of EV penetration and the adoption of charging infrastructure was conducted based on government targets rather than relying on current data regarding the actual numbers and trends of EVs and chargers in Malaysia. The availability of accurate and up-to-date data on the number of EVs, their battery characteristics, chargers, and user charging behaviors in Malaysia would contribute to further enhancing this research work.

Pathogenic variations in Colletotrichum spp. causing chilli anthracnose in Peninsular Malaysia

AbstractIn Peninsular Malaysia, Colletotrichum fioriniae, Colletotrichum fructicola, Colletotrichum scovillei, Colletotrichum siamense and Colletotrichum truncatum are the causative pathogens of chilli anthracnose. In the present study, the pathogenic variability and virulence levels of these five Colletotrichum spp. were evaluated. Isolates of C. fioriniae, C. fructicola, C. scovillei, C. siamense and C. truncatum were tested for pathogenicity using red and green Capsicum annuum and red and green Capsicum frutescens. Pathogenicity tests were conducted using spore suspensions and mycelial plugs on wounded and nonwounded chilli fruits. All isolates tested on the wounded chilli fruits caused anthracnose symptoms with variable disease severity and virulence. In nonwounded chilli fruits, only isolates of C. scovillei (n = 7) and C. truncatum (n = 5) caused infection. C. fioriniae, C. fructicola, C. scovillei, C. siamense and C. truncatum showed variability in pathogenicity and virulence levels in red and green chilli fruits of Ca. annuum and Ca. frutescens. Pathogenicity tests on wounded and nonwounded chilli fruits can be used to identify pathotypes within anthracnose pathogen populations. This is important for strategizing the effective disease management of chilli anthracnose.

A Single-Buyer Model of Imbalance Cost Pass-Through Pricing Forecasting in the Malaysian Electricity Supply Industry

The imbalance cost pass-through (ICPT) is a flexible component of the incentive-based regulation (IBR) that empowers power producers to adjust tariffs in response to variable fuel prices, thereby enhancing the economic resilience of electricity generation. In Malaysia, the Energy Commission has conducted biannual reviews of fuel and other generation costs. Any cost savings or increases identified during these reviews will be passed on to customers in the form of rebates or surcharges. Meanwhile, if an increment in the ICPT price signal can be provided to electricity providers and consumers, early preparation for operation budgeting can be realised, and energy management program development can be properly prepared. Due to this reason, this study proposes ICPT price forecasting for the electricity market in Peninsular Malaysia that will benefit the stakeholders. The study aims to construct an ICPT-related baseline model for the peninsular generation data by employing three forecasting methods. The forecasting performance is analysed using the mean absolute percentage error (MAPE). In light of our findings, the ARIMA method is one of the most accurate forecasting methods for fuel prices compared to the moving average (MA) and LSSVM methods. The observed price differences between the ARIMA and LSSVM models for ICPT are minimal. The ICPT price for July–December 2022 and January–June 2023 is MYR 0.21/kWh for the ARIMA and MYR 0.18/kWh for LSSVM, which are close to the actual TNB’s ICPT tariff. As for forecasting, the ICPT price is expected to drop in the next announcement. The findings of this study may have a positive impact on the sustainability of the energy sector in Malaysia.

Myxobolus acanthogobii Hoshina, 1952 and Myxobolus selari n. sp. (Myxosporea: Myxobolidae) infecting brain of commercial fishes in Terengganu, Malaysia.

Myxosporean infection in marine water fishes has drawn less attention than in freshwater fishes, which resulted in a higher taxonomic variety in freshwater in Malaysia. This study aimed to address the gap by conducting a myxosporean survey on two commercially significant marine fish species, Nemipterus furcosus (Valenciennes) (Eupercaria incertae sedis: Nemipteridae) and Selar crumenophthalmus (Bloch) (Carangiformes: Carangidae), collected from the northeastern part of peninsular Malaysia. During the examination of the organs, two distinct Myxobolus Bütschli, 1882 species were discovered in the brain tissue of these fishes, despite the absence of any observable pathological signs. The two Myxobolus species were characterized through morphometry, morphology, and analysis of partial small subunit ribosomal RNA (18S rDNA) gene. As a result, Myxobolus acanthogobii Hoshina, 1952, which infects 2.3% of N. furcosus, is synonymous with a myxobolid species commonly found in Japanese waters, based on its morphological traits, tissue tropism, and molecular diagnostics. Furthermore, a novel species, Myxobolus selari n. sp., was described, infecting the brain of one (11%) individual S. crumenophthalmus. This unique species displayed distinctive features, placing it within a well-supported subclade primarily comprising brain-infecting myxobolids. Maximum likelihood analysis further revealed the close relationships among these brain-infecting myxobolids, underscoring the significance of tissue tropism and host taxonomy for myxobolids. This study represents the initial documentation of Myxobolus species within the southern South China Sea, shedding light on the potential diversity of marine myxosporean in this region. This article was registered in the Official Register of Zoological Nomenclature (ZooBank) as urn:lsid:zoobank.org:pub:7C400E35-7CB8-4DEE-92B7-F75FF3926441.

Prioritising Important Plant Areas (IPAs) among the limestone karsts of Perak, Malaysia

SummaryThe flora of limestone karsts is exceptionally rich, due in particular to the wide array of microhabitats that limestone outcrops support. However, in Peninsular Malaysia limestone outcrops are heavily exploited for the quarry industry, cave temples, leisure venues and the development of geoparks, hence the limestone flora is amongst the most threatened biodiversity in the Peninsula. The 95 limestone karsts in Perak are currently known to support 538 species, representing c. 44.2% of the total limestone flora of Peninsular Malaysia. Of these, 13.2% (71 species) are endemic to the Peninsula of which 10 species are hyper-endemic (i.e. restricted to a single karst), 108 (20%) are threatened with extinction and 6 are considered likely to be Extinct. Typical of limestone in Peninsular Malaysia, a single karst harbours only a fraction of the total limestone flora such that a network of karsts is required to capture maximum plant diversity. Through evaluation of data from field surveys, herbarium specimens and the literature, 27 of the Perak karsts were found to trigger Important Plant Area (IPA) status, i.e. they harbour important populations of threatened species, outstanding botanical richness and/or are important examples of threatened habitats that in Perak include the foothills and limestone forest. Fifteen karsts were identified for priority conservation measures based on Conservation Priority Scores (CPS), a quantitative methodology based on endemic and threatened status. With the addition of two species-rich karst sites, 17 karsts are recommended as the first iteration of the network of priority IPA sites for Perak that together conserve 90% (483 species) of the Perak limestone plant diversity, 93% (66) of the endemic species and 94.4% (102) of the threatened species. CPS is found to be more reliable than using total species richness for assessing conservation importance and we also demonstrate that karst size and isolation are not primary indicators of range-restricted plant diversity. Significant knowledge gaps still exist, with 59 karsts in Perak without botanical surveys, and with many rare species having not been recollected for over 30 years, emphasising the need for further botanical research in these important and threatened landscapes.

Data to the Malaysian Liverwort Flora, IV: a New Species of Mastigopelma Mitt. (Lepidoziaceae) from Cameron Highlands, Peninsular Malaysia

The new species, Mastigopelma latiffiana G. E. Lee, E. Pesiu et X. L. He, discovered in Pen-insular Malaysia, is described and illustrated as a new addition to the genus Mastigopelma Mitt., of the family Lepidoziaceae. The new species is corticolous, growing on a tree branch in a moist montane forest in Cameron Highlands, Pahang, at 1,900 m alt. It is characterised by the leafy shoots arising from stolons, branches, when present, all ventral-intercalary, and terminal branching lacking; asymmetrical leaves with almost straight ventral margins, rounded to truncate leaf apices, entire-margined leaves, thickened cell walls with nodular trigones, and glistening-homogeneous oil bodies (2–4 per cell); and retuse to blunt teethed underleaf apices. This discovery has increased the total number of known species of Mastigopelma Mitt. to five. An identification key to all the species of the genus is presented.

A high-resolution perspective of extreme rainfall and river flow under extreme climate change in Southeast Asia

Abstract. This article provides high-resolution information on the projected changes in annual extreme rainfall and high- and low-streamflow events over Southeast Asia under extreme climate change. The analysis was performed using the bias-corrected result of the High-Resolution Model Intercomparison Project (HighResMIP) multi-model experiment for the period 1971–2050. Eleven rainfall indices were calculated, along with streamflow simulation using the PCR-GLOBWB hydrological model. The historical period 1981–2010 and the near-future period 2021–2050 were considered for this analysis. Results indicate that, over former mainland Southeast Asia, Myanmar will face more challenges in the near future. The east coast of Myanmar will experience more extreme high-rainfall conditions, while northern Myanmar will have longer dry spells. Over the Indonesian maritime continent, Sumatra and Java will suffer from an increase in dry-spell length of up to 40 %, while the increase in extreme high rainfall will occur over Borneo and mountainous areas in Papua. Based on the streamflow analysis, the impact of climate change is more prominent in a low-flow event than in a high-flow event. The majority of rivers in the central Mekong catchment, Sumatra, Peninsular Malaysia, Borneo, and Java will experience more extreme low-flow events. More extreme dry conditions in the near future are also seen from the increasing probability of future low-flow occurrences, which reaches 101 % and 90 %, on average, over Sumatra and Java, respectively. In addition, based on our results over Java and Sumatra, we found that the changes in extreme high- and low-streamflow events are more pronounced in rivers with steep hydrographs (rivers where flash floods are easily triggered), while rivers with flat hydrographs have a higher risk in terms of the probability of low-flow change.

Understanding The Mimicker: Epidemiological Pattern and Determinant of Melioidosis Mortality in Negeri Sembilan, Malaysia.

Melioidosis, a tropical infectious disease caused by Burkholderia pseudomallei, is epidemic in most region in Southeast Asia with high case fatality. However, there is scanty information regarding the disease's epidemiological pattern, demographics, and underlying risk factors. This 5-year retrospective study of 185 confirmed cases which were taken from the Negeri Sembilan Melioidosis Registry between 2018 and 2022. We aim to describe the incidence, mortality rate, case fatality, relationship with meteorology, and factors that influence mortality in this central region of Peninsular Malaysia. Incidence rate (IR) of melioidosis in Negeri Sembilan is varied at 1.9 to 5.1 with mean of 3.1 in 100,000 population per year. IR varied between districts in the state from zero to 22.01 in 100,000 population per year. Mortality rate were ranged from 0.17 to 0.74 cases with mean of 0.44 cases in 100,000 population per year. The case fatality rate of this state scattered from 8.70% to 16.67%. There were no significant linear associations between cases and deaths with monthly rainfall and humidity. The mean age of patients was 52.8 years, predominated with age around 41-60 years old. Males (77.8%) predominated, and the majority of cases were Malays (88.9%) and had exposed to soil related activities (74.6%). Mortality from melioidosis was more likely in Bumiputera and non-Malaysians (p<0.05). Patients who had at least one comorbidity were at a higher risk of death from melioidosis (p<0.05). Diabetes mellitus was found in 41.1% of all identified cases, making it a major underlying risk factor for both developing and dying from melioidosis (aOR:19.32, 95%CI:1.91-195.59, p<0.05). Hypertension and mortality status in melioidosis are also significantly correlated (aOR: 7.75, 95% CI: 2.26-26.61, p<0.05). The epidemiological patterns of cases reported from Negeri Sembilan are consistent for the most part from previous studies in other states in Malaysia and global with regard to its incidence, case fatality, demographic and predisposing chronic diseases. Diabetes mellitus and hypertension were significantly linked to increased mortality among all determinants.

The Prevalence and Determinants of Anemia Among Indigenous (Orang Asli) Children in Peninsular Malaysia: A Systematic Review.

Low- and lower-middle-income countries bear the greatest burden of anemia, particularly those living in rural settings such as an indigenous community. The objective of this systematic review is to recognize the prevalence of anemia and its determinants among the Orang Asli children in Peninsular Malaysia. A web-based search of PubMed, Web of Science, Scopus, Medline, and ProQuest from January 2000 to June 2022, using specified search/MeSH (Medical Subject Headings) terms and keywords, was conducted. The search identified studies reported the prevalence of anemia among the children of Orang Asli and its causes. Eight studies were included in the final analysis. The prevalence of anemia among the Orang Asli children was high (61.6%). Most research has focused primarily on iron-deficiency anemia and soil-transmitted helminth infections. Other causes include female gender, mothers with low education levels, and low household incomes. Despite being a public health concern, this study found no studies associating Orang Asli children with hereditary anemia and malaria, which is a limitation. In conclusion, the Orang Asli children are more likely to have anemia compared with the general Malaysian population. To overcome this, a comprehensive examination of the determinants of anemia in this community is required. Thus, interventions can be personalized.

Spore Germination of Diplazium simplicivenium Holtt. (Athyriaceae) in Peninsular Malaysia

Diplazium simplicivenium Holtt. a species of fern in Peninsular Malaysia. This study reports an efficient method for D. simplicivenium spore sterilisation and the effect of plant growth regulators (PGRs) via green globular bodies (GGB). Sterilisation with 0.1% mercuric chloride effectively allowed spore germination. The result showed that the culture media supplemented with 0.5 mg/L gibberellin positively affects the weight of GGB and the number of shoots with significant differences (ANOVA, p &lt; 0.05). The soaking technique established in this study for spore sterilisation is an efficient approach, and the optimal plant and concentration of plant hormones were identified. This procedure can be applied to other indigenous ferns and closely similar species.

Ethnoprimatology reveals new extended distribution of critically endangered banded langur Presbytis femoralis (Martin, 1838) in Pahang, Malaysia: Insights from indigenous traditional knowledge and molecular analysis.

The banded langur (Presbytis femoralis) is a critically endangered primate, restricted to Johor, Malaysia, with an estimated population size of less than 500 individuals. Traditionally, distribution studies on this highly threatened primate have relied on conventional methods such as DNA identification, live counting, and camera trapping. However, ethnoprimatology offers an alternative approach to data collection, involving the active participation of indigenous and local communities possessing valuable knowledge and experience with local primate species. This study employed an integrated approach incorporating ethnoprimatology by utilizing pooled local expert opinion, local surveys, interviews, and fecal DNA analysis, resulting in a novel distribution range for the banded langur. The combination of expert opinions revealed this species' most optimistic distribution scenario across Johor and Pahang, inhabiting various ecosystems, including lowland forests, peat swamps, and human-modified landscapes. Further interviews and surveys conducted within the Orang Asli community in Tasik Chini and Tasek Bera have provided additional support for the revised distribution, documenting occurrences of banded langur utilization in indigenous practices, such as food consumption, cultural beliefs, medicinal applications, and craftsmanship. Phylogenetic analysis demonstrated genetic differentiation between populations in Johor and Pahang, with the populations in the southern part of Peninsular Malaysia likely serving as ancestral sources for other populations. Consequently, this study not only elucidated the updated distribution of banded langur through DNA records and direct observations but also established the efficacy of ethnoprimatology as a precursory tool for uncovering the present distribution patterns of other primate species in Malaysia.

Site occupancy of native terrestrial mammals in oil palm landscapes is driven by the synergy of land sparing and sharing strategies

The conversion of tropical rainforests into industrial oil palm monocultures has detrimental effects of local biodiversity. Although some medium-sized mammals have demonstrated a degree of adaptability in oil palm landscapes, the factors that influence their ability to persist in such human-altered environments remain obscure. Here, we investigated the site occupancy and activity pattern of the mammals in oil palm landscapes in Peninsular Malaysia. We deployed 81 camera traps throughout six oil palm cultivation areas with two distinct management styles (three sites each in organized smallholdings and industrial plantations). Smallholdings had higher site occupancy of native animal species than industrial plantations. The site occupancy of the mammals was influenced by the proximity to continuous forest, forest patches and riparian vegetation. Landscape metrics are characteristics that affect land sparing strategy, allowing wildanimals in agricultural landscapes to thrive in their habitat despite human threats. At stand-level, the detection of animals was determined by elevation, undergrowth vegetation cover/height, canopy cover, oil palm height, quantity of oil palm fruits, and prune stack thickness. Mammal occupancy was higher in the smallholdings due to the proximity to continuous forest. We recommend improving landscape heterogeneity and connectivity in oil palm matrix to promote species mobility and diversifying oil palm management away from monoculture farming. Our findings indicate that incorporating land sharing and sparing strategies into the oil palm matrix is necessary to conserve biodiversity and maintain ecological services. This implies that industry stakeholders ought not to disregard either land sparing or land sharing.

Population structure in Mixornis tit-babblers across Sunda Shelf matches interfluvia of paleo-rivers

Rivers constitute an important biogeographic divide in vast areas of tropical rainforest, such as the Amazon and Congo Basins. Southeast Asia’s rainforests are currently fragmented across islands divided by sea, which has long obscured their extensive history of terrestrial connectivity as part of a vast (but now submerged) subcontinent – Sundaland – during most of the Quaternary. The role of paleo-rivers in determining population structure in Sundaic rainforests at a time when these forests were connected remains little understood. We examined the coloration of museum skins and used the genomic DNA of museum samples and freshly-collected blood tissue of a pair of Sundaic songbird species, the pin-striped and bold-striped tit-babblers (Mixornis gularis and M. bornensis, respectively), to assess the genetic affinity of populations on small Sundaic islands that have largely been ignored by modern research. Our genomic and morphological results place the populations from the Anambas and Natuna Islands firmly within M. gularis from the Malay Peninsula in western Sundaland, even though some of these islands are geographically much closer to Borneo, where M. bornensis resides. Our results are consistent with the course of Sundaic paleo-rivers and the location of the interfluvia they formed, and add to a small but growing body of evidence that rivers would have been of equal biogeographic importance in Sundaland’s former connected forest landscape as they are in Amazonia and the Congo Basin today.