Sunda Islands Research Articles

The distribution of the Malay civetViverra tangalunga(Carnivora: Viverridae) across Southeast Asia: natural or human-mediated dispersal?

The Malay civet Viverra tangalunga Gray, 1832 is a fairly large viverrid that has a wide distribution in both the Sundaic and Wallacea regions of Southeast Asia. We investigated the genetic diversity of V. tangalunga by analysing the mitochondrial DNA of 81 individuals throughout its range in order to elucidate the evolutionary history of this species and to test the hypotheses of natural dispersal and/or potential human introductions to some islands and regions. Our phylogenetic analyses revealed that V. tangalunga has a low matrilinear genetic diversity and is poorly structured geographically. Borneo is likely to have served as the ancestral population source from which animals dispersed during the Pleistocene. Viverra tangalunga could have naturally dispersed to Peninsular Malaysia, Sumatra, and Belitung, and also to several other Sunda Islands (Bangka, Lingga, and Bintang in the Rhio Archipelago), and to Palawan, although there is possible evidence that humans introduced V. tangalunga to the latter islands. Our results strongly suggested that V. tangalunga was transported by humans across Wallace's Line to Sulawesi and the Moluccas, but also to the Philippines and the Natuna Islands. Our study has shown that human-mediated dispersal can be an important factor in understanding the distribution of some species in this region. © 2014 The Linnean Society of London

<!--[if gte mso 9]><xml> <o:OfficeDocumentSettings> <o:RelyOnVML/> <o:AllowPNG/> </o:OfficeDocumentSettings></xml><![endif]-->Gynura tambuyukonensis (Asteraceae), an obligate ultramafic species endemic to Mount Tambuyukon (Kinabalu Park, Sabah, Malaysia)<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:TrackMoves/> <w:TrackFormatting/> <w:PunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:DoNotPromoteQF/> <w:LidThemeOther>EN-US</w:LidThemeOther> <w:LidThemeAsian>X-NONE</w:LidThemeAsian> <w:LidThemeComplexScript>TH</w:LidThemeComplexScript> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:ApplyBreakingRules/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <w:DontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:DontVertAlignCellWithSp/> <w:DontBreakConstrainedForcedTables/> <w:DontVertAlignInTxbx/> <w:Word11KerningPairs/> <w:CachedColBalance/> </w:Compatibility> <w:DoNotOptimizeForBrowser/> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/>

A new endemic species of Gynura is described and illustrated. Gynura tambuyukonensis is found exclusively (‘obligate’) on ultramafic soils between bare peridotite bedrock at 2450–2550 m above sea level on Mount Tambuyukon (Kinabalu Park) in Sabah (Malaysia) on Borneo Island. On the basis of the morphological features, this new taxon appears to be related to G. sundaiaca F.G. Davies of the Lesser Sunda Islands and Timor. The diagnostic morphological characters are discussed and information about its habitat, ecology and distribution is provided.

Diversification of Southeast Asian mammals during the Quaternary glaciation: insights from the genomic era

Southeast (SE) Asia refers to the region east to the Philippine islands, west to the Indian subcontinent, north to central China and south to the Sunda islands. This region includes six of the world's 25 biodiversity hotspots and is of strategic significance in global biodiversity conservation. The complicated geological and climatological history of this region has resulted in extremely high species diversity and endemism. Two classic biogeographic boundaries, the Wallace Line and the Isthmus of Kra, divide SE Asia into the Indochinese province to the north and Sundaic province to the south. Because the Indochinese and Sundaic provinces are connected today through the Malay Peninsula and the Sunda shelf was exposed for the majority of time during the Quaternary glaciation, previous biogeographic studies have proposed that gene flow occurred between mainland and different island populations causing low divergence in the region. However, recent molecular genetic studies have reported that migration of terrestrial mammal populations was not as great as previously thought due to ecological restrictions. Thus, deep vicariant divergence was present in several mammals as early as two million years ago and appeared not to have been affected by gene flow following the formation of land bridges during later glacial periods. Furthermore, the super eruption of

Basin isolation and oceanographic features influencing lineage divergence in the humbug damselfish <I>(Dascyllus aruanus)</I> in the Coral Triangle

The Coral Triangle is a hotspot for marine species diversity as well as for intraspecific genetic diversity. Here, we used nuclear RAG2 and mitochondrial D-Loop genes to identify deep genetic divergence among Dascyllus aruanus (Linnaeus, 1758) populations across relatively short scales within the Coral Triangle. Mitochondrial clades different by >20 mutational steps were completely isolated from one another across the distance between Java and the Lesser Sunda Islands, and also showed frequency differences in the eastern and western Philippines. Evidence for population structure in the Sulu Sea and at the Lesser Sunda Islands was also identified. Our results suggest that the Sulu Sea Throughflow, Bohol Sea Throughflow, Indonesian Throughflow, signatures of extinction events from Pleistocene land barriers, and other past and present forces may be potential factors leading to lineage divergence of D. aruanus, and that these hypotheses should be tested in further studies.

Visitors and Settlers: Notes on Timor and the Chinese as Cultural and Economic Brokers (Sixteenth to Nineteenth Centuries)

Located on the fringe of the Southeast Asian “Mediterranean”, Timor only played a minor role in a vast exchange zone that interconnected diverse maritime centres to each other, despite being the largest of the Lesser Sunda Islands. Confined to an area with dense forests and steep mountains and without a maritime tradition of their own, the Timorese had few contacts with the “outside world”; these were essentially limited to encounters with foreigner visitors who were mainly attracted by one specific local product: the fragrant wood known as sandalwood (Santalum album). Sandalwood had a wide range of applications in different parts of Asia; it was used in medicine, for cosmetics, religious ceremonies, the production of scented objects, and for many other purposes. Among the early foreigners sailing to Timor in quest of sandalwood one finds Chinese, Malay and Javanese travellers and merchants. During much of the early modern period sandalwood was also the major and often exclusive reason for the Portuguese and Dutch to gradually extend colonial rule over Timor’s many ethnic groups and polities. The earliest record of Timor in Chinese texts dates back to the mid-thirteenth century; there is a brief reference to sandalwood and “the two countries of Dagang and Diwu” where it came from. The first name has not been identified, the second stands for Timor.1 The oldest description of the island is again found in a Chinese source. According to this work, called Daoyi zhilue and sometimes dated to c. 1350, there were several sandalwood ports. The author also lists the goods traded in exchange for sandalwood; he adds that high profits were

Pandan (Pandanaceae) in Flores Island, East Nusa Tenggara, Indonesia: an economic-botanical study

The people in the Indonesian province of Nusa Tenggara Timur (then East Lesser Sunda Islands) consist of many ethnic groups, each with their own local languages. The island of Flores is the second largest island within the East Lesser Sunda Islands. The island is inhabited by 10 ethnic groups, in which four are regarded as the dominant groups: Flores, Ende, Lio and Manggarai. The pandan flora of the island is still largely unknown; the same is for their ethnobotany. The aim of this current study is to know the traditional usages and potential uses of pandan flora in the Flores Island. The study was carried out in three regencies: Ende, Nagekeo and Manggarai. The result of this study shows that there are four species of Pandanus (P. amaryllifolius, P. dubius, P. kaernbachii, and P. tectorius) and one species of Freycinetia (F. insignis) are recorded from the areas understudy. The presence of P. kaernbachii in Flores Island is a new record. The people also recognises the diversity of Pandanaceae, especially from the genus Pandanus, in which they are known by local names such as “panda”, “re’a”, “waku”, and “mbojo”. Main usages of Pandanus are as material sources for handicrafts (mats, coffee bowls, and hats), dye, flavourings, funeral offering, and ornamental plant.

Genetic variation and population genetic structure of Rhizophora apiculata (Rhizophoraceae) in the greater Sunda Islands, Indonesia using microsatellite markers

Genetic variations within and among Rhizophora apiculata populations in the Greater Sunda Islands of Indonesia were studied using microsatellite markers. The study found 38 alleles on five loci in 15 populations. The observed (H(o)) and expected (H(e)) heterozygosity values are 0.338 and 0.378, respectively. Inbreeding effect from self-pollination might explain its heterozygote deficiency. Population genetic differentiation (F(ST) = 0.381) was similar to other mangrove species. The genetic diversity of R. apiculata populations along the coastline inside the archipelago (e.g., Buleleng, Donggala, Mamuju, and Takalar) was higher than those of population along the coastline outside the archipelago, especially northern Sumatra populations (i.e., Langkat, Tapanuli Tengah, Dumai, and Padang). The isolation by distances and sea currents directions as well as their connectivity might affect the gene flow and genetic exchange. The more isolated with fewer connections by sea currents, the smaller gene flow and genetic exchange observed between populations. The higher genetic exchange, on the contrary, occurred when population location was closer to the meeting point of the sea currents. The study also showed that the patterns of sea current movement seemed to have influence genetic clustering of populations which fell into three main groups (Sunda Shelf Mangroves) and one isolated population (New Guinea Mangroves).

First report on the herpetofauna of Ataúro Island, Timor Leste

We describe for the first time the terrestrial herpetofauna of Ataúro Island, Timor-Leste, a small mountainous island in the Inner Banda Arc of the Lesser Sunda Archipelago. The island supports a fauna of ten lizard species in three families (Gekkonidae, n = 5; Scincidae, n = 4; Varanidae, n = 1) and four snake species in three families (Colubridae, n = 3; Typhlopidae, n = 1; Viperidae, n = 1). In addition to a set of lizards (e.g., Cryptoblepharus, Eutropis, Gehyra, Gekko, Hemidactylus, Lamprolepis) and snakes (e.g., Lycodon, Ramphotyphlops, Trimeresurus) typical for the Lesser Sunda Islands, there appear to be undescribed endemic species of Cyrtodactylus, Eremiascincus, and Varanus on Ataúro. Our surveys to date have not revealed the presence of any amphibians, turtles, or crocodiles.

Ocean variability along the southern coast of Java and Lesser Sunda Islands

The sea surface height data from 1992 through 2012 in the Eastern Indian Ocean, the 6 sets of hydrographic data sparsely spanning 1990–2001 in water south of Java–Bali, and the 24 shipboard acoustic Doppler current profiler (ADCP) data across the Ombai Strait during 1997–2000 were used as a combined dataset to understand sea level and current variability along the southern coast of Java and Lesser Sunda Islands. The first two dominant empirical orthogonal function (EOF) modes capture combined seasonal with interannual and seasonal variability that account for 44.5 and 19.9 % of the total variances caused by El Nino Southern Oscillation and Indian Ocean Dipole events, and by the seasonal change of the Asian monsoon, respectively. The geostrophic current and ADCP data show that the eastward and westward currents are distinguishable via the vertical profiles of current velocity. The eastward-flowing South Java Current (SJC) is characterized by a large vertical shear and shallower diminishing depth of about 150 m and it is increased to 300 m in the presence of the Indian Ocean Kelvin Waves (IOKWs). In contrast, the westward current is dominated by the Indonesian Throughflow (ITF) with no vertical shear and has uniform current in the upper 300 m layer. The coastally trapped SJC and IOKWs are responsible for the eastward current. The SJC is not observed in the westward current because of non-existence of coastally trapped modes. The ITF and SJC generate persistent cyclonic (cold) and anticyclonic (warm) mesoscale eddies, respectively, in waters south of eastern Java.

Plio‐Pleistocene out‐of‐Australia dispersal in a camaenid land snail

AbstractAimCamaenidae are amongst the most diverse land snail groups in Southeast Asia and Australasia, but their phylogeny and biogeography are poorly understood. The monophyly and biogeographical origin of the Australian species has remained uncertain. Being reported from north‐western Australia as well as from the Lesser Sunda Islands, the genus Rhagada is crucial to our understanding of camaenid biogeography. By resolving the phylogeny of Rhagada, we aim to uncover spatial and temporal patterns of its diversification at the interface between Oriental and Australian biogeographical regions.LocationNorth‐western Australia, Lesser Sunda Islands.MethodsWe implemented Bayesian and maximum likelihood methods to generate the most complete mitochondrial phylogeny of Rhagada land snails to date. Divergence times of clades were estimated by employing a relaxed molecular clock and two internal calibrations from fossil and tectonic data. Ancestral areas of clades were inferred using character history reconstruction based on parsimony, as implemented in Mesquite.ResultsRhagada clustered into eight well‐supported clades that are restricted to certain geographical areas. Species from the Kimberley, Western Australia, formed the earliest branching clades. A single Lesser Sunda clade was sister to a radiation in the Western Australian Pilbara. Molecular age estimates placed the evolutionary origin of Rhagada between the late Miocene and early Pleistocene, and dispersal from Western Australia onto the Lesser Sunda Islands in a period between the mid‐Pliocene and early Pleistocene.Main conclusionsThe camaenid Rhagada originated in the Kimberley and subsequently expanded its range through the Pilbara and into the Shark Bay area, probably during the late Pliocene and mid‐Pleistocene. From the Kimberley, Rhagada snails colonized the Lesser Sunda Islands probably not before 1.9 Ma following emergence of the youngest islands, which may have acted as ‘stepping stones’. Over‐sea dispersal might have occurred during the mid‐Pleistocene when lowered sea levels facilitated faunal exchange across the region.

Vanda perplexa (Orchidaceae): a new species from the Lesser Sunda Islands

Vanda perplexa, a new species of orchid from the Lesser Sunda Islands is described and discussed.

The enigmatic bovid Duboisia santeng (Dubois, 1891) from the Early–Middle Pleistocene of Java: A multiproxy approach to its paleoecology

During the Pleistocene, the Sunda Islands to which Java belongs were frequently connected with the East Asian mainland, permitting faunal elements of Indo-Chinese origin entering Java. Therefore, most Javanese mammalian taxa are close if not identical to their mainland relatives. In particular, three fossil bovids, commonly found in the Early–Middle Pleistocene “Stegodon-Homo erectus fauna” (Bubalus palaeokerabau, Bibos palaesondaicus, and Epileptobos groeneveldtii), do not show any feature consistent with the evolutionary pattern of typical insular mammals. However, a fourth Javanese bovid, Duboisia santeng has been regarded as a typical insular endemic species due to its small size. However, since Duboisia has been claimed to be present in the late Middle Pleistocene of what is now peninsular Malaysia, the actual endemic insular status of this taxon needs further confirmation.In this study we aim to contribute to the debate by analyzing the autecology of Javanese Duboisia santeng, delving into its paleobiogeographic history and evolution. The multiproxy approach adopted here (body mass estimate, paleohabitat predictions, morphological comparison, mesowear analysis and Dental Areal Surface Texture Analysis DASTA) gave mutually consistent results and proved to be useful in supporting hypothesis regarding the complex evolution of insular faunas.

Review of potter wasps with a petiolate metasoma excluding so-called "Zethinae" (Hymenoptera: Vespidae: Eumeninae) in the Lesser Sunda Islands of the Indonesian Archipelago

Twenty species and six subspecies of nine genera of eumenine wasps with a petiolate metasoma occurring in the LesserSunda Islands are listed. New synonymies are proposed for Delta campaniforme campaniforme (Fabricius 1775) (=D.campaniforme gracilior Giordani Soika 1986, syn. nov.) and D. nigriculum Giordani Soika 1986, stat. nov. (=D. campaniformerendalloide Giordani Soika 1993, syn. nov.). Eumenes piriformis de Saussure and E. inconspicuus Smith arenewly recorded from the Lesser Sunda Islands; E. pius Giordani Soika, D. nigriculum Giordani Soika, D. pyriforme (Fabricius),D. sciarum (van der Vecht), Pareumenes nigerrimus van der Vecht, and Labus vandervechti Giordani Soika, arenewly recorded from some islands of the Lesser Sunda. Hitherto unknown male of P. nigerrimus is described.

Les primates quaternaires de Song Terus (Java Est, Indonésie) : implications paléobiogéographiques et archéozoologiques pour l’Asie du Sud-Est

Bones of non-human primates account for 70% of early Holocene mammal remains found in archaeological sites in the Punung region. Facial parts of monkeys have been found with pre-Neolithic human burials, as noted by van Heekeren. This thesis attempts to explain human/primate relationships froman analysis of the stratified remains of primates in the early Holocene layers in the caves of Song Terus, Gunung Sewu and East Java. Particular attention is given to the species Trachypithecus auratus, which accounts for 96% of the Song Terus primate bones. These are described morphologically and in relation to other genera and species of monkeys, including Macaca and Presbytis. Primate speciation patterns in the islands of South-East Asia suggest continuous connections between the Sunda Islands through forested terrain during the Pleistocene, making it unlikely that the region ever had a completely treeless savanna corridor during the glacial periods (which would have inhibited the movement of monkeys between islands). In parallel with a zooarchaeological approach, a study of tooth micro-wear suggests commensalism between certain monkeys and humans at Song Terus, especially in the period from 9000 to 5000 years ago.

Out of Borneo: Neogene diversification of Sundaic freshwater crabs (Crustacea: Brachyura: Gecarcinucidae: Parathelphusa)

AbstractAimWe investigate the biogeographical history of the species‐rich Sundaic freshwater crab genus Parathelphusa (family Gecarcinucidae). In particular, we ask to what extent eustatic sea‐level fluctuations influenced diversification and species distribution. We test the prediction that sea‐level fluctuations in the course of the Pleistocene glaciations increased speciation rates.LocationMalay Peninsula, Greater Sunda Islands (Borneo, Java, Sumatra, Sulawesi), Bali and the Philippines (Palawan, Mindoro).MethodsPhylogenetic inference calculations were based on partial mitochondrial cytochrome c oxidase subunit I (COX1), 16S ribosomal RNA and nuclear histone subunit 3 (H3) genes using maximum likelihood, maximum parsimony and Bayesian approaches. Divergence time estimation was performed with beast based on external substitution rates. Biogeographical analyses were conducted with a parametric likelihood method (Lagrange) and a Bayesian method (BayesTraits). Lineage diversification was studied with a lineage‐through‐time plot, and a maximum likelihood approach as implemented in the R package laser.ResultsWe propose a Late Miocene age for the most recent common ancestor of Parathelphusa, with an ancestral range covering Borneo and the adjacent part of Sundaland. The evolution of six lineages pre‐dates the Pliocene, five of them occurring on Borneo. Subsequent dispersal during the Miocene and Pliocene extended the range of Parathelphusa to the Philippines, Sulawesi, the Malay Peninsula and Sumatra, and, during the Late Pliocene and Pleistocene, to Java. Pleistocene divergence occurred between species from the Malay Peninsula and Sumatra, Java and Sumatra, and Java and Borneo.Main conclusionsAlthough low sea levels during the Pleistocene in all probability facilitated the dispersal of freshwater crabs among the Greater Sunda islands (excluding Sulawesi, which is not part of the Sunda Shelf), there is no complete Pleistocene geographical admixture of species, and pre‐Pleistocene biogeographical patterns were retained. Furthermore, Pleistocene vicariance did not lead to an increased diversification rate in Parathelphusa. Instead, single colonization events out of Borneo during the Neogene, followed by species radiation (e.g. on Palawan and Sulawesi), contributed substantially to species diversity in Parathelphusa. This involved the crossing of marine barriers such as the Wallace Line.

Phylogenetic resolution and systematics of the Asian tree frogs, Rhacophorus (Rhacophoridae, Amphibia)

Li, J.T., Li, Y., Murphy, R.W., Rao, D.‐Q. & Zhang, Y.‐P. (2012). Phylogenetic resolution and systematics of the Asian tree frogs, Rhacophorus (Rhacophoridae, Amphibia). —Zoologica Scripta, 41, 557–570.The treefrog genus Rhacophorus, a large genus with 80 species, has a wide range, occurring eastward from India to China, Japan, South‐east Asia, the Greater Sunda Islands and the Philippines. The phylogenetic relationships and taxonomic recognition of many species are very controversial. To stabilize the taxonomy, the phylogenetic relationships among about 52 species are investigated from 96 samples using mtDNA sequence data. Matrilineal relationships based on maximum likelihood and Bayesian inference methods resolve three well‐supported lineages (A, B and C), although the phylogenetic relationships among three lineages remain ambiguous. Analyses support recognition of two previously assigned subgenera, Leptomantis and Rhacophorus, and these correspond to lineages A and B, respectively. Given that we have three strongly supported lineages, that these lineages are morphologically distinct, and the constrained geographic distributions of these groups, we recognize each lineage as a taxon. Subgenus Leptomantis includes species mainly from Malaysia, Indonesia and the Philippines. Subgenus Rhacophorus contains a mix of species occurring in India, Indochina and southern China. Lineage C accommodates species distributed mostly in East Asia, including Japan and China. Based on genetic and morphological data from type localities, the taxonomic recognition of some species needs to be reconsidered. Rhacophorus pingbianensis and Polypedates spinus are considered as junior synonyms of Rhacophorus duboisi. Specimens of Rhacophorus rhodopus from Vietnam and Hainan, China likely represent an undescribed, cryptic species.

Correct name for the Asian Brown Flycatcher (Aves: Muscicapidae, Muscicapa)

Broad-billed flycatchers of East Siberia, which migrate to winter in south-east Asia south to the Greater Sunda Islands, were first described as new for science by Raffles (1822: 312) from Sumatra under the name Muscicapa latirostris. The species was known as Muscicapa latirostris Raffles (or latirostris in combination with other generic names) for over a century (e.g. Dresser 1902: 252, Hartert 1907: 477, Vaurie 1959: 331), but since the 1930s it has been called either Muscicapa latirostris Raffles or Muscicapa daurica Pallas (see below for the history). This dichotomy continues; some authors prefer latirostris (e.g. Peklo 1987; Stepanân 1990, 2003; Nakano & Murakami 2001; Popov 2004; Kwon et al. 2006; Takeuchi 2007; Kolbin 2008; Gavrilov 2011; Sonina & Durnev 2011), while others prefer daurica (e.g. Banks & Browning 1995; Clarke et al. 2009; Tojo 2009; Mohan & Kumar 2010; David 2011).

Bauhinia pottsii G. Don var pottsii, KOLEKSI DARI KALIMANTAN YANG DITEMUKAN KEMBALI

Bauhinia is one of the largest genus in Caesalpiniaceae family and distributed in all tropical area. One among 300 species of Bauhinia is Bauhinia pottsii G. Don. This species is distributed from Southern Myanmar, Thailand, Cambodia, Malay Peninsular, Borneo, Sumatra, Jawa, Bali and Lesser Sunda islands. It was recorded that one specimen was originated from East Kalimantan and collected in 1925. During exploration in Kampung Temula, Kecamatan Nyuatan, Kabupaten Kutai Barat, East Kalimantan, Bauhinia pottsii G. Don var pottsii was found after about 87 years.

INDENTIFYING PATTERNS OF SATTELITE IMAGERY USING AN ARTIFICIAL NEURAL NETWORK

An artificial neural network analysis based on the self-organizing map (SOM) was used to examine patterns of satellite imagery. This study used 3 × 4 SOM array to extract patterns of satellite-observed chlorophyll-a (chl-a) along the southern coast of the Lesser Sunda Islands from 1998 to 2006. The analyses indicated two characteristic spatial patterns, namely the northwest and the southeast monsoon patterns. The northwest monsoon pattern was characterized by a low chl-a concentration. In contrast, the southeast monsoon pattern was indicated by a high chl-a distributed along the southern coast of the Lesser Sunda Islands. Furthermore, this study demonstrated that the seasonal variations of those two patterns were related to the variations of winds and sea surface temperature (SST). The winds were predominantly southeasterly (northwesterly) during southeast (northwest) monsoon, drived offshore (onshore) Ekman transport and produced upwelling (downwelling) along the southern coasts of the Lesser Sunda Islands. Consequently, upwelling reduce dSST and helped replenish the surface water nutrients, thus supporting high chl-a concentration. Finally, this study demonstrated that the SOM method was very useful for the identifications of patterns in various satellite imageries.

Strengthening of the Northeast Monsoon over the Flores Sea, Indonesia, at the time of Heinrich event 1

Paleoclimate evidence from South America and Asia has been interpreted to indicate that tropical rainfall migrated southward during the Northern Hemisphere cooling associated with Heinrich stadial 1 (HS1), an event of massive iceberg discharge to the North Atlantic ca. 18‐15 ka. Although arid conditions associated with such a shift are well documented in southern Asia, as far south as Borneo, debate still exists regarding the precipitation response in southern Indonesia and Australia during HS1. This study utilizes concentrations of the long-lived nuclide 232 Th as a proxy for detrital riverine input and 230 Th normalization to estimate the history of preserved fl uxes reaching the seafl oor in the Flores Sea, located between southern Sulawesi and the Lesser Sunda Islands, Indonesia. Because the only source of 232 Th to the ocean is continental minerals, this proxy is a robust indicator of continental weathering. The 230 Th normalized burial fl uxes of lithogenic and biogenic matter demonstrate that both detrital and biogenic fl uxes in the Flores Sea were higher during HS1 than any other period in the past 22 k.y. High detrital fl uxes indicate enhanced precipitation runoff from surrounding landmasses during a period of maximum southward shift of the Intertropical Convergence Zone. This study further constrains the northern limit of enhanced rainfall associated with a southward shift of Australian monsoon-related rainfall at the time of HS1 and highlights the value of 232 Th as a proxy of continental input to deep-sea sediment records.