Congenital heart disease (CHD) occurs in over half of individuals with 22q11.2 deletion syndrome (22q11.2DS) and the types of lesions range from mild to severe. To determine the basis of variation in cardiac phenotypes we analyzed demographic data from 3,016 unrelated individuals with 22q11.2DS from centers in the Northeast US, Canada, Europe, South America, Israel and Australia. Most individuals in this cohort had a 3 million base pair hemizygous deletion between low copy repeat, LCR22 A-D (87.2%), while some had nested deletions. We performed multivariable mixed-effects logistic regression and uncovered significant differences between CHD phenotypes and basic demographic features. Individuals with the A-D deletion had a lower risk of persistent truncus arteriosus (OR = 0.37, 95% CI 0.18-0.75) but a higher risk of septal defects (OR = 4.7, 95% CI 1.7-12.8) compared to those with the smaller A-B deletion, suggesting distinct developmental pathways sensitive to 22q11.2 gene dosage. In addition, genome-wide genetic principal components (PCs) were associated with specific CHD subtypes, including reduced risk of pulmonary stenosis or atresia with other heart lesions (PC2; OR = 0.73, 95% CI 0.61-0.87) and increased risk of abnormal origin of the subclavian arteries (PC4; OR = 2.6, 95% CI 1.4-4.9), indicating that background genetic variation modifies heart lesion-specific susceptibility. Together, these results suggest that both deletion size and background genetic variation shape the highly variable cardiac phenotypes in 22q11.2DS.

Abstract Understanding changes in intraseasonal rainfall variability is critical for improving sub-seasonal prediction. While the amplification of intraseasonal rainfall variability across Australia has been reported, the spatial heterogeneity of this intensification has been overlooked. Here, we observe that the intraseasonal rainfall variability has been intensified, particularly over northeastern Australia during the wet season (November–April) over the past four decades. The intensified intraseasonal rainfall variability is primarily attributed to enhanced intensity of precipitation events, rather than drier spells. Moisture budget analysis indicates that the intensification of intraseasonal abnormal rainfall events over northeastern Australia is primarily due to the strengthened vertical advection of background moisture caused by the intraseasonal vertical motion anomalies. In this process, the strengthening of intraseasonal vertical velocity driven by changes in intraseasonal wind convergence plays a dominant role, accounting for over 90%, whereas the effect of background moisture changes is relatively less significant. Our findings highlight northeastern Australia as a hotspot for amplified intraseasonal rainfall variability, rather than the whole of Australia. This study provides fundamental insights into northern Australia’s changing climate, and highlights the important role of intraseasonal circulation on northeastern Australia rainfall variability.

ABSTRACT This study provides a comprehensive evaluation of the latest generation of climate models in simulating the dynamics of the Australian summer monsoon over northern Australia. The analysis focuses on both spatial and temporal characteristics of precipitation, low‐level circulation, monsoon onset and retreat as well as the representation of El‐Niño Southern Oscillations (ENSO) teleconnections. Using multiple observational datasets and standard performance metrics, including correlation, root mean square error, standard deviation and bias, models are assessed and ranked based on their ability to simulate observed monsoon features. The results reveal persistent model biases, including overestimated precipitation, underestimated wind intensity, delayed monsoon onset and retreat (by up to 2 weeks in some models), a weak or overly uniform simulation of ENSO influence and in some cases interannual rainfall variability is more than double the observed value. These limitations affect the models' ability to capture the seasonal cycle and interannual variability of the monsoon. Importantly, performance varies significantly even among models from the same modelling institution, underscoring the need for individual model evaluation. Using a subset of high‐performing models that accurately capture key monsoon features leads to more consistent and robust projections. These high‐performing models simulate increased rainfall in northeast Australia (+15 to +20%) by the late 21st century under a high emissions scenario. In contrast, low‐performing models simulate much weaker increases (0 to +5%). This study highlights both the progress and ongoing challenges in current‐generation climate models, contributing to improved understanding and model selection for future monsoon projections across northern Australia.

Sediment conduits like erosive canyons and channels are common morphological elements of submarine landscapes down to abyssal depths. While canyon-channel systems connected to slopes and shallow water are well studied, detached sediment-routing systems emerging in deeper waters have received less attention, especially in carbonate settings. We study the sedimentary architecture and evolution of an extensive canyon-channel system in the ‘Willis Passage’, a marine strait between the Magdelaine and Willis carbonate banks (Queensland Plateau, northeast Australia). The canyon-channel system is detached from the slopes of the carbonate banks, emerges at depths of >500 m and runs over more than 100 km towards the slope break of the carbonate plateau. The canyon is several kilometres wide and several tens of metres deep. Morphological edges (knickpoints) occur along the canyon course; one with a plunge pool at its downstream foot wall. Current ripples and coarse-grained lag deposits at the floor of the canyon indicate bottom-current activity and possibly winnowing of fine-grained sediment. The seafloor outside the canyon is intersected by bundles of grooves (linear seafloor cuts), tens of kilometres long. Sedimentological and morphological characteristics indicate that canyon-channel system and grooves are shaped by eastward-flowing bottom currents, which is in a direction counter to the dominant westward-flowing oceanic current regime. We propose that eastward-flowing sediment-laden bottom currents originate from the channelization of oceanic currents by the carbonate edifices of the Queensland Plateau, paired with tidal pumping in the narrow passages between the banks. This mechanism is most efficient during episodes of lowered sea level, while bottom currents are much weaker during sea-level highstand. Our seismic data reveal the existence of buried individual canyon-channel systems and document that the Queensland Plateau underwent episodic changes in the local current regime since the upper Miocene. Based on new geophysical and oceanographic data, as well as video observations of the seafloor, we show that slope-detached deep-water canyon-channel systems act as a conveyor, routing sediment from carbonate platforms to the deep ocean. As a link between the neritic realm and abyssal depths, these systems are important agents of dismantling and degradation of carbonate platforms and underline the role of bottom currents in shaping these depositional environments. • Slope-detached canyon-channel systems occur in deeper waters surrounding the carbonate banks. • Canyons are >100 km long, several kilometres wide, and tens of meters deep. • Submarine landforms include block fields, > 10 km long grooves, plunge pools, and mega-ripples. • Canyon formation by bottom currents is opposed to the prevailing oceanic current regime.

Abstract El Niño‐Southern Oscillation (ENSO), where the central‐east tropical Pacific is unusually warm (El Niño) or cold (La Niña), is known to influence Australian rainfall. Here, we detail the extent of ENSO's influence on Australian monthly rainfall distributions and clarify its many complexities. We show La Niña to be a long‐lasting and wide‐spread intensifier of Australian rainfall throughout its lifecycle, particularly on extreme monthly rainfall. The reduction of rainfall during El Niño is comparatively limited; confined mainly to El Niño's developing phase and the southeast and northeast of Australia. A further complexity shows El Niño can intensify monthly rainfall during its mature phase. Within these broader impacts of ENSO are strong spatial and temporal differences, such that the expected rainfall impacts may not be consistently felt at the local‐scale. We propose methods to account for these complex climatic impacts at scales comparable to a river catchment scale.

Abstract This study investigates the impact of the interaction between large‐scale and local‐scale forcings in regulating rainfall patterns and their propagation over coastal areas of Northeast (NE) Australia using a convective‐scale regional model run for 180 days. Over the coastal areas, spatially heterogeneous rainfall patterns are evident in both radar observations and model simulations. By classifying the characteristics of three distinct rainfall groups, we found that the rainfall propagation modulates the average rainfall patterns. Modelling results suggest that the large‐scale background wind and local‐scale land–sea breeze circulations are two important factors driving rainfall propagation. Offshore rainfall propagation, which is frequently observed in coastal regions in the tropics, occurs during the days with weak easterlies near the surface and strong upper‐and mid‐level westerlies. Rainfall is triggered during the afternoon by convergence driven by the sea breeze and then propagates offshore during the nighttime with the land breeze density current and large‐scale background westerlies. In contrast, onshore rainfall propagation is observed during days with strong background easterlies from the surface to upper levels. For the No‐Propagation group, rainfall occurs during the afternoon due to the convergence of sea breezes and low‐level background westerlies, and it persists over land during the nighttime with low‐ and mid‐level easterlies. Our results also suggest that the background wind regimes associated with different phases of intraseasonal variability modulate the direction and strength of rainfall propagation, leading to different coastal rainfall patterns.

Two recent events in far north-east Australia and Auckland, New Zealand, produced rainfall of a seemingly unprecedented nature, with the Australian event involving Tropical Cyclone Jasper and the New Zealand case involving a tropical low affecting Auckland. The aim of this paper is to identify mechanisms that produced the extreme rainfall. The analyses of the wind and thermal structure found that multiple factors occurring simultaneously were responsible for the extreme rainfall for both events. The problem is to deduce if this was result of climate change and global warming or long, expected intervals between such unique synoptic events arriving at a particular location on the globe. In the Jasper case, a search is conducted for similar extreme events dating back to the 19th Century and weather systems producing daily record rainfall. These record rainfall events are more common in the past two centuries than in recent decades over much of Australia. With the Auckland case, the extreme rainfall was unprecedented although four events on a larger scale involving tropical cyclones had huge impacts on New Zealand. Severe Tropical Cyclone Gabrielle occurred soon after the Auckland event, preceded by three others in 1988, 1968 and 1936. The structure of the Auckland low is shown to be unique when compared with Gabrielle. The latter was more intense and closer to Auckland than the former; however, it produced much less rain in the study area. These results will hopefully assist climate researchers in determining whether the events involving Jasper and the Auckland low were rare occurrences triggered by the simultaneous combination of several factors, or if they were influenced by the effects of a warming world.

The problem of estimating the ratio of the means of a two-component Poisson mixture model is considered, when each component is subject to zero-inflation, i.e., excess zero counts. The resulting zero-inflated Poisson mixture (ZIPM) model can be viewed as a three-component Poisson mixture model with one degenerate component. The EM algorithm is applied to obtain frequentist estimators and their standard errors, the latter determined via an explicit expression for the observed information matrix. As an intermediate step, we derive an explicit expression for standard errors in the two-component Poisson mixture model (without zero-inflation), a new result. The ZIPM model is applied to simulated data and real ecological count data of frigatebirds on the Coral Sea Islands off the coast of Northeast Australia.

ABSTRACTThis research examines rock art and dendroglyphs in the Wet Tropics of northeast Australia to investigate their relationship to linguistic social identity. The region was selected for its complex socio‐cultural landscape, marked by a diversity of languages in a distinct, relatively small area. The study was co‐designed with nine First Nations partner organisations representing five language groups and employed rock art methodologies and interviews with First Nation knowledge holders. Findings reveal that neither rock art nor dendroglyph motifs correspond neatly with linguistic boundaries. Within a single language area, stylistic variations were observed—rock art is more figurative in the east and abstract in the west, while dendroglyphs, found only in the eastern Wet Tropics, feature predominantly abstract designs. Rather than signifying socio‐cultural differences, the dendroglyphs and rock art illustrate connections. Senior custodians identify dendroglyphs as story places, clan symbols, and sites of cultural significance, reflecting a deep and enduring relationship by First Nations with these rare cultural expressions. This study contributes new insights into dendroglyphs and rock art in Queensland's Wet Tropics rainforests, challenging assumptions that stylistic boundaries align strictly with language groups and significantly broadening knowledge of Australian dendroglyphs.

About 300 Aboriginal languages were spoken in Australia, classified into two groups: Pama-Nyungan (PN), comprised of one language Family, and Non-Pama-Nyungan (NPN) with more than 20 language Families. The Yolngu people belong to the larger PN Family and live in Arnhem Land in northern Australia. They are surrounded by groups who speak NPN languages. This study, using nuclear genomic and mitochondrial DNA data, was undertaken to shed light on the origins of the Yolngu people and their language. The nuclear genomic sequences of Yolngu people were compared to those of other Indigenous Australians, as well as Papuan, African, East Asian, and European people. With the agreement of Indigenous participants, samples were collected from 13 Yolngu individuals and 4 people from neighboring NPN speakers, and their nuclear genomes were sequenced to a 30× coverage. Using the short-read DNA BGISEQ-500 technology, these sequences were mapped to a reference genome and identified ~24.86 million Single Nucleotide Variants (SNVs). The Yolngu SNVs were then compared to those of 36 individuals from 10 other Indigenous populations/locations across Australia and four worldwide populations using multidimensional scaling, population structure, F3 statistics, and phylogenetic analyses. Using the above methods, we infer that Yolngu speakers are closely related to neighboring NPN speakers, followed by the Weipa population. No European or East Asian admixture was detected in the genomes of the Yolngu speakers studied here, which contrasts with the genomes of many other PN speakers that have been studied. Our results show that Yolngu speakers are more closely related to other PN speakers in the northeast of Australia than to those in central and Western Australia studied here. Yolngu and the other Australian populations from this study share Papuans as an out-group. The study presented here provides an account of the nuclear and mitochondrial genomic diversity within the PN Yolngu Aboriginal population. The results show the Yolngu sample and their NPN neighbors have a strong genetic relationship. They also offer evidence of ancestral links between the Yolngu and PN-speaking populations in Cape York. From earlier fingerprint studies, consistent with the genomic results shown here, we consider a movement of people from the east into northeast Arnhem Land, associated with the flooding of the Sahul Shelf, estimated to have occurred between about 11 and 8 Kya ago. Several Yolngu myths point to such a movement. It is suggested that the spread of the PN language or its speakers may have influenced the population structure of the Yolngu. Further genomic studies, with larger samples, of populations to the east of the Yolngu around the Gulf of Carpentaria into Cape York are required to test this hypothesis. Our results imply that PN did not spread with the movement of people across the continent; rather, the PN languages diffused among the different populations. It seems clear that the languages dispersed and not the people. The low level of relatedness detected between the Yolngu people and the people of the central arid desert of Australia suggests a long period of separation with different patterns of migration. Beyond Australia, Yolngu are most closely related to the Papuan people of New Guinea.

Abstract Boulder fields are a typical feature of granitoid landscapes. Previously reported boulder fields are commonly an accumulation of boulders on gently undulating surfaces; however, sometimes boulders form high mountains. The Black and Melville Mountains, northeast Australia, have relative heights of 300 to 500 m and are entirely covered by granitoid boulders and blocks. They are underlain by Permian granitoid rocks intruded into the Silurian–Devonian strata. We performed field surveys, UAV observations and satellite image analysis of these mountains using Digital Elevation Models (DEMs) obtained from satellite data. Melville Mountain has low‐relief top surfaces surrounded by steep slopes covered by boulders with (sub)angular blocks. The low‐relief surfaces are assumed to be an exhumed Jurassic unconformity, below which the granitoid rocks became corestones (boulders) by subsurface spheroidal weathering. The limited exposure of the bedrock suggests that the granitoids were columnar jointed, which facilitated the spheroidal weathering. The steep slopes are covered by boulders originating from the low‐relief top surfaces and rock blocks from the rock columns below the zone of spheroidal weathering. Black Mountain lacks low‐relief top surfaces and comprises steep slopes covered with rock blocks. Boulders on Black Mountain exist at the feet of steep slopes and are mixed with rock blocks. The boulders are probably from previous low‐relief top surfaces that are now lost. Columnar joints, subsurface spheroidal weathering, uplift and erosion are essential for the formation of the high mountains covered by boulders and blocks of granitoid.

ABSTRACTThe meridional, Permo–Triassic Bowen Basin of NE Australia became a retroarc foreland basin in the late Permian, with a mapped foredeep axis (Taroom Trough) running north–south adjacent to the eastern edge of the basin. The present outline of the basin is, nonetheless, shaped by significant structural deformation along its eastern margin, and stratigraphic pinch‐outs and erosional truncation in the west. The plan form of the basin thus gives a potentially misleading representation of the basin's original shape and extent. By analysing wireline log data from over 1000 drillholes, we developed isochore, net sand thickness, and net‐to‐gross maps, which inform a new set of palaeogeographical maps for the three upper Permian formations of the Bowen Basin (Peawaddy Formation, Black Alley Shale, and Bandanna Formation, in ascending order). These maps were further refined using palaeocurrent data from outcrops and validated against logged vertical sections from various parts of the basin. Isochore plots for the three formations indicate abrupt truncation of contour lines along the structural eastern margin, in the Taroom Trough. This pattern is interpreted as evidence of significant erosion of stratigraphy along the eastern basin margin during contractional deformation. Based on these findings, we posit that the Taroom Trough synclinal axis does not represent the original foredeep axis, which we propose was located farther east and was erosionally excised. The configurations of sand‐prone depositional systems, and the preservation of upper Permian strata outside the structural basin boundaries, support the hypothesis that the original eastern depositional edge of the basin extended farther east than its current structural boundary. Similarly, truncation and westward onlap of formations along the western margin suggest that the basin's original western boundary lay beyond its present margin. Based on the truncated isochores and other criteria, we estimate that the preserved part of the basin is ~50% of its original area.

Abstract This study investigates the role of the interaction between the Madden–Julian oscillation (MJO) and local‐scale forcings in regulating precipitation and its diurnal variation during the austral summer over coastal areas in northeast (NE) Australia using radar data. The variation of rainfall is influenced by both large‐scale and local‐scale forcings. During the enhanced convection phases of the MJO, widespread increased rainfall signals are generated by large‐scale forcings associated with the MJO, but the environmental factors controlling the type and amount of precipitation during each phase are different. By contrast, the locally enhanced rainfall during suppressed convection phases of the MJO likely results from the interaction of mesoscale land–sea breezes, strong large‐scale background winds and topography. Different responses of mean and heavy precipitation to the MJO occur in some MJO phases. The impact of the MJO on diurnal rainfall characteristics is spatially inhomogeneous and likely regulated by local forcings. Although stratiform rainfall is more common, convective rainfall predominantly contributes to the total precipitation over coastal regions of NE Australia. The MJO's influence on convective rainfall is generally stronger and more statistically significant than its impact on stratiform rainfall. The widespread increased rainfall probability during the enhanced convection phases is likely due to increases in both stratiform and convective rainfall. In contrast, the locally enhanced precipitation signal during some suppressed convection phases mainly results from an increase in convective rainfall.

Abstract The interannual variability of northern Australian (NA) rainfall is caused by local processes as well as remote teleconnections, many of them being interrelated. Their influence evolves throughout the wet season, from October through April. Using a stepwise linear regression and examining individual months, we identify the key drivers for rainfall variability over northwest and northeast Australia. Our research shows that the El Niño‐Southern Oscillation (ENSO), followed by local sea surface temperatures (SSTs), are the key sources of rainfall variability in October and November. More specifically, the Arafura and Coral Sea SSTs contribute to rainfall variability over northwest Australia, while the Coral Sea SSTs strongly impact on northeast Australian rainfall during these months. The combined ENSO and local SST indices explain up to 50% of variance in observed NA spring monthly mean rainfall. However, the SST influence from both seas breaks down with the onset of the Australian summer monsoon in late December, and by January, SST indices explain zero variance in rainfall. Instead, December to March rainfall variability is associated with a wind‐evaporation feedback, which is particularly strong over northwest Australia. The evaporation index is the only predictor that we investigated that can explain any variance in northwest Australian rainfall in January. While the more purely monsoonal northwest of Australia is dominated by variability internal to the monsoon system, rainfall variability in the northeast retains some influence from remote climate drivers throughout the monsoon season. Further research is needed to clarify the processes and timescale involved in the wind‐evaporation feedback.

Abstract Coastal wetlands have long been identified as ecosystems that can ameliorate N inputs into the ocean. The processes associated with N uptake, transformation, and losses are relatively well understood for temperate wetlands; however, information on tropical wetlands is scarce. In this study, we conducted a whole ecosystem approach to measure N processes within tropical mangroves in the Moresby estuary in northeast Australia. We measured N stocks (trees and soils), inputs from sedimentation, fixation, and accumulation as woody biomass, and outputs through denitrification, anammox, and soil respiration (N2O emissions). Potential denitrification was detected along anammox (average, min‐max) at 883 (485–1,450) gN ha−1 day−1, followed by sediment accumulation with 108 (0–375) gN ha−1 day−1, and tree uptake with 93 (13–153) gN ha−1 day−1. Lower rates were found for N fixation with 45 (0–260) gN ha−1 day−1 and soil respiration as N2O with uptakes of −0.36 (−2.7 – 0.40) gN ha−1 day−1. Overall, mangroves in the Moresby estuary are fixing some N in their standing litter while removing NO3 and NH4+ from the water column through denitrification and anammox, temporarily storing N as woody biomass, and accumulating particulate N in their sediments. These mangroves are also functioning as sinks of N2O. Thus, the protection and restoration of these mangroves provide water quality and climate benefits.

Phosphorus dynamics in P-depleted sub-surface of cropping soils in northeast Australia: Evaluating the potential of APSIM for simulation and the influence of soil properties

The Australian Bureau of Meteorology provides flood forecasting and warning services across Australia for most major rivers in Australia, in cooperation with other government, local agencies and emergency services. As part of this service, the Bureau issues a flood watch product to provide early advice on a developing situation that may lead to flooding up to 4 days prior to an event. This service is based on (a) an ensemble of available Numerical Weather Prediction (NWP) rainfall forecasts, (b) antecedent soil moisture, stream and dam conditions, (c) hydrological forecasts using event-based models and (d) expert meteorological and hydrological input by Bureau of Meteorology staff, to estimate the risk of reaching pre-specified river height thresholds at locations across the continent. A flood watch provides information about a developing weather situation including forecasting rainfall totals, catchments at risk of flooding, and indicative severity where required. Although there is uncertainty attached to a flood watch, its early dissemination can help individuals and communities to be better prepared should flooding eventuate. This paper investigates the utility of forecasts of daily gridded national runoff to inform the risk of riverine flooding up to 7 days in advance. The gridded national water balance model (AWRA-L) runoff outputs generated using post-processed 9-day Numerical Weather Prediction hindcasts were evaluated as to whether they could accurately predict exceedance probabilities of runoff at gauged locations. The approach was trialed over 75 forecast locations across North East Australia (Queensland). Forecast 3-, 5- and 7-day accumulations of runoff over the catchment corresponding to each location were produced, identifying whether accumulated runoff reached either 95% or 99% historical levels (analogous to minor, moderate and major threshold levels). The performance of AWRA-L runoff-based flood likelihood was benchmarked against that based on precipitation only (i.e., not rainfall–runoff transformation). Both products were evaluated against the observed runoff data measured at the site. Our analysis confirmed that this runoff-based flood likelihood guidance could be used to support the generation of flood watch products.

Abstract Soil carbon (C) sequestration by restoring degraded grasslands with adequate management practices offers significant opportunities for climate change mitigation while remaining highly uncertain. In this study, a combination of a biogeochemical model DayCent‐CABBI and eddy covariance (EC) flux towers was applied to evaluate soil C sequestration potential (at a depth of 0–0.3 m) of management strategies in subtropical grasslands. DayCent‐CABBI was calibrated for grasslands in northeast Australia using biomass and soil organic carbon (SOC) data from a long‐term trial and then fine‐tuned using EC flux tower data from seven sites in the region. The model was then validated with cumulative net ecosystem exchange, biomass, and SOC, resulting in root mean square errors of 1.16, 0.88, and 2.81 Mg C ha −1 , respectively. The model was used to project long‐term changes in SOC stocks under innovative management practices (time‐controlled grazing and pasture legume incorporation), estimating soil C sequestration by 0.37–0.48 and 0.15–0.26 Mg C ha −1 year −1 toward 2050 with the respective practices. This study confirms the validity of the Measure, Model, and Verification (MMV) approach to estimate and project soil C sequestration for evaluating SOC methodologies by grassland management within a shorter period than soil sampling—measuring the baseline SOC, modeling the C dynamics with the calibrated DayCent‐CABBI, and verifying the projected soil C sequestration with EC flux tower data.

Aristolochiaceae s.l. , included in the order Piperales, consists of 8 genera ( Asarum , Saruma , Aristolochia , Thottea , Pararistolochia , Hydnora , Prosopanche and Lactoris ) and more than 700 species. [Plants…, 2022]. The geography of distribution and the history of the dispersal of this family are of great scientific interest in many terms, because species of this family live in different parts of the continents, thus forming disjunctions in their distribution areas. The range of the family covers the western and eastern coasts of America, North and Central Africa, North-East Australia, South-East and East Asia, Siberia and the most of Europe. During the work, the morphological, biological and ecological characteristics of the representatives of the family were studied. The analysis of the molecular genetic and morphological data of selected Aristolochiaceae s.l. taxa was carried out on the basis of the results of our own researches. We compared the results of the reconstruction of the probable distribution tracks with the available paleobotanical materials. The result of our work was the reconstruction of possible routes of settlement and methods of distribution Aristolochiaceae s.l. representatives, based on complex molecular-genetic and morphological data.

The Torres Strait Islands lie between Cape York Peninsula, north-east Australia, and the southern coast of Papua New Guinea. The vertebrate fauna of these islands is a relatively depauperate mix of Australian and New Guinean species, with only two endemic species described to date. Here we describe a new species of Nactus gecko discovered during a targeted survey of Dauan Island in the northern Torres Strait. Nactus simakal sp. nov. is a genetically (ND2 mtDNA) and morphologically highly distinct species, with a banded pattern and a slender, elongate form. It is saxicoline, living on deeply piled boulder habitat, and is likely to be restricted to Dauan Island. Nactus simakal sp. nov. is currently known from a very small area and further surveys, and assessment of current and potential threats, are required to assess the conservation status of this species. Nactus simakal sp. nov. is similar in general appearance to N. galgajuga (Ingram, 1978), which is restricted to boulder-pile habitat 750 km to the south in mainland north-east Queensland but is readily distinguished from that species morphologically and genetically.