Proterozoic microfossils from the Mara Dolomite Member, Emmerugga Dolomite, McArthur Group, from the Northern Territory, Australia

An assemblage of microfossils from the mid-Proterozoic Mara Dolomite Member of the Emmerugga Dolomite, McArthur Group, Northern Territory, Australia, has been studied. The assemblage contains 10 species, of which one is new. The classification of Proterozoic microfossils is reviewed and a morphographic scheme adopted. The new assemblage is compared with other McArthur Group assemblages, and the differences between the assemblages are explained in terms of environmental differences. Comparison with other microfossil assemblages world-wide, suggests that these assemblages have stratigraphic potential.     

Farmers and their fires,fishers and their fish: Production and productivity in pre-European South-East Queensland

Ian Walters is a Professor of Anthropology at Northern Territory University, Casuerina, Northern Territory.     

Higher taxonomic descriptors for vegetation classification

A model of direct and diffuse solar radiation on slopes of varying angle and aspect suggests that radiation differences within hilly terrain are maximized in the beginning of the dry season in the monsoon tropics. The differences between north and south facing slopes are greater than those found during the summer in the temperate zone. Within a study area near Mt. Bundey, Northern Territory, floristic and structural vegetational variability is closely related to June radiation as estimated by the model. However, the distribution patterns of monsoon thicket and eucalypt forest relate more to relative five protection than to the effects of incident radiation on temporal patterns of moisture availability. Within both major formations, site rockiness is an important influence on vegetation floristics and structure, both for five protection and through its influence on moisture availability.     

Some observations on the breeding, age structure, dispersion and habitat of populations of Macropus robustus and Macropus antilopinus (Marsupialia)

Differences in breeding, population structure, dispersion and habitat are described between various species and subspecies of wallaroo (Macropus robustus robustus; M. r. cervinus; M. r. alligatoris; M. r. erubescens; Macropus antilopinus; Macropus bernardus).
Pouch young of Macropus robustus erubescens in western New South Wales were born throughout the year, while in both M. r. alligatoris and M. antilopinus then Northern Territory, most pouch young found were born during March and April.
In the populations of wallaroos in western New South Wales and the Northern Territory where there had been no systematic shooting of wallaroos for many years, 11|X% of the animals were immature. In the New England district of New South Wales where regular shooting occurs, 46|X% of the animals were immature.
The habitat of M. r. alligatoris of the Northern Territory was very similar to that of M. erubescens in inland Australia, amongst rocky hills and gullies. M. antilopinus , which is sympatric with M. r. alligatoris in the Northern Territory, also occurred in the rocky hills, but it was also found in open savannah woodland in flat and gently undulating country.
M. r. erubescens and M. r. alligatoris were almost always seen alone or in pairs, while M. antilopinus often formed larger groups.     

Isolation of Sindbis (alphavirus) and Leanyer viruses from mosquitoes collected in the Northern Territory of Australia, 1974.

Mosquitoes collected near Darwin, Northern Territory, in 1974 yielded two virus strains. One was identified as Sindbis virus, not previously isolated from the Northern Territory. The other is antigenically distinct from viruses previously isolated from arthropods in Australia, and the name "Leanyer" is proposed for it. Its properties suggest that it may be a togavirus serologically unrelated to available alphaviruses and flaviviruses.     

Fire,storm, flood and drought: The vegetation ecology of Howards Peninsula,Northern Territory,Australia

Twenty different communities, characteristic of the coastal vegetation of the northern portion of the Northern Territory, were recognized by photo-interpretation and ground truthing a 20 × 20 km area near Darwin. Data collected from 161 quadrats placed throughout the study area showed a strong relationship between subjective and objective measures of vegetation structure. Photopattern is best explained by a combination of structural, lifeform and floristic data. The mangrove, grassland, forest and woodland communities form a complex spatial pattern. Variations in moisture regime, through the interaction of topography and soils with temporal fluctuations of salt and/or fresh water supply, appear to best explain vegetation distribution. Three anomalously open eucalypt communities are interpreted as being the consequence of a severe tropical cyclonic storm which destroyed much of Darwin in 1974. These communities are frequently burnt by the nearby urban population and possess layers of sapling size eucalypts, although the height and density of the regrowth appears to vary with site quality. It is argued that fire is a characteristic of the seasonal climate, and that the fire pattern largely reflects the vegetation pattern. Occasional severe tropical storms also affect vegetation types differently. The greatest amount of windthrow occurs in moist monsoon forests while the eucalypts on well drained soils are more windfirm, but remain obviously damaged for over 10 years.     

Floating vegetation mats on a floodplain billabong in the Northern Territory of Australia

The floristics and physical structure of a floating mat of vegetation in the Finniss River area of the Northern Territory are described. During the dry season floating mats contain green productive vegetation when the adjacent flood plains are dry and many of the plants are withered. At this time insects are more abundant on the mats than on the adjacent flood plain. Some flood plain vertebrates appear to concentrate their activity on floating mats during the dry season. During the period 1963 to 1978 the area of floating mat in the Finniss River study area was greatly reduced, probably as a result of high densities of feral water buffalo (Bubalis bubalus).(Present address: c/o 38 Hardy Terrace, East Ivanhoe, Victoria 3079).(Present address: c/o 38 Hardy Terrace, East Ivanhoe, Victoria 3079).     

New species and new record of Tetranychus Dufour from Australia, with a key to the major groups in this genus based on females (Acari: Prostigmata: Tetranychidae)

A new species of spider mite, Tetranychus bunda sp. n., is described and illustrated from Australia. It was found damaging the foliage of Desmodium tortuosum (Sw.) DC. (Fabaceae) in Darwin, Northern Territory. In addition, the geographical range of Tetranychus fijiensis Hirst is extended to include Australia. This species was found in the Northern Territory feeding on frangipani ( Plumeria sp., Apocynaceae), betel palm ( Areca catechu L., Arecaceae) and Macarthur feather palm ( Ptychosperma macarthurii [H. Wendl. ex Veitch] (H. Wendl. ex Hook. f., Arecaceae)). Details of the biology of T. bunda sp. n. and T. fijiensis are given. A key to the major groups of Tetranychus Dufour of the world, based on females, is presented and species known to occur in Australia are outlined.     

Phylogeography of the antilopine wallaroo (Macropus antilopinus) across tropical northern Australia

The distribution of antilopine wallaroo, Macropus antilopinus, is marked by a break in the species’ range between Queensland and the Northern Territory, coinciding with the Carpentarian barrier. Previous work on M. antilopinus revealed limited genetic differentiation between the Northern Territory and Queensland M. antilopinus populations across this barrier. The study also identified a number of divergent lineages in the Northern Territory, but was unable to elucidate any geographic structure. Here, we re‐examine these results to (1) determine phylogeographic patterns across the range of M. antilopinus and (2) infer the biogeographic barriers associated with these patterns. The tropical savannahs of northern Australia: from the Cape York Peninsula in the east, to the Kimberley in the west. We examined phylogeographic patterns in M. antilopinus using a larger number of samples and three mtDNA genes: NADH dehydrogenase subunit 2, cytochrome b, and the control region. Two datasets were generated and analyzed: (1) a subset of samples with all three mtDNA regions concatenated together and (2) all samples for just control region sequences that included samples from the previous study. Analysis included generating phylogenetic trees based on Bayesian analysis and intraspecific median‐joining networks. The contemporary spatial structure of M. antilopinus mtDNA lineages revealed five shallow clades and a sixth, divergent lineage. The genetic differences that we found between Queensland and Northern Territory M. antilopinus samples confirmed the split in the geographic distribution of the species. We also found weak genetic differentiation between Northern Territory samples and those from the Kimberley region of Western Australia, possibly due to the Kimberley Plateau–Arnhem Land barrier. Within the Northern Territory, two clades appear to be parapatric in the west, while another two clades are broadly sympatric across the Northern Territory. MtDNA diversity of M. antilopinus revealed an unexpectedly complex evolutionary history involving multiple sympatric and parapatric mtDNA clades across northern Australia. These phylogeographic patterns highlight the importance of investigating genetic variation across distributions of species and integrating this information into biodiversity conservation.     

Cluster analysis,ordination and dominance-structural classification applied to diverse tropical vegetation at Jabiluka,Northern Territory

One hundred and seven sample plots were established on a study area at Jabiluka, Northern Territory, and detailed quantitative floristic and structural data were collected. Data collection was by sampling both on aerial photographs and in the field, and both sets of data were used to describe the primary floristic types and structural sub-types. Cluster analysis (Orloci 1967, 1969), polar ordination (Mathews 1977) and Specht's (1970, 1977) approach to vegetation classification were used to analyse the data. Two independent clustering techniques, one based on art information measure and the other on a measure of within group dispersion, produced very similar dendrograms. The analyses consistently separated the plots into three major groups - floodplain, dryland and sandstone landscapes; within these groups 15 floristic associations and eight structural formations were identified. The environmental parameters associated with the various groups were substrate type, and seasonal inundation from the Magela Creek system. The results of ordination did not highlight any environmental parameters not already made evident by cluster analysis.     

Effects of frequent fires and grazing on stable nitrogen isotope ratios of vegetation in northern Australia

The ratios of stable nitrogen isotopes expressed as δ¹⁵N values can indicate the openness of nitrogen cycles in ecosystems. Southwards through the Northern Territory, values of foliar δ¹⁵N in savanna trees increase as mean annual rainfall decreases from approximately 1800 mm to approximately 750 mm, with foliar δ¹⁵N thereafter decreasing toward arid central Australia. Recent literature argues that this pattern is caused by higher grazing intensity in semi‐arid savannas, but counter views have attributed the pattern more directly to variations in aridity. In this paper, grazed and ungrazed sites in a semi‐arid savanna are compared, and it is shown that grazing has a relatively small effect on the positive foliar δ¹⁵N values of grasses, but no effect on δ¹⁵N values of trees. This gives little support to the argument that variations in grazing pressure at the scale of hundreds of kilometres could result in detectable differences in the foliar δ¹⁵N values of trees. I then compare the semi‐arid savannas with mesic savannas, where fires are frequent, and with mesic rainforests, which are rarely burnt. Greater foliar δ¹⁵N values in rainforest and fire‐excluded mesic savannas than in frequently burnt savannas suggests that fire regimes affect foliar δ¹⁵N. The previously observed pattern in δ¹⁵N values along the rainfall gradient in the Northern Territory is consistent with trends in fire frequency and possible direct effects of fire, but further work is required to determine the relative impacts of aridity and fire. Within a particular rainfall regime, foliar δ¹⁵N values may indicate historical fire frequencies.     

Kakaducaris glabra gen. nov., sp. nov., a new freshwater shrimp from the Kakadu National Park,Northern Territory,Australia, Crustacea: Decapoda: Palaemonidae with the designation of a new subfamily Kakaducaridinae

A new species of palaemonid shrimp from the Northern Territory Kakadu National Park is described and illustrated. Kakaducaris glabra, gen, nov., sp. nov., can not be satisfactorily referred to the described subfamilies of the Palaemonidae and a new subfamily Kakaducaridinae is designated (see addendum).     

Distribution of Giardia duodenalis Assemblages A and B among Children Living in a Remote Indigenous Community of the Northern Territory,Australia

Giardiasis is a communicable gastrointestinal disease caused by Giardia duodenalis and two genetic assemblages, A and B, cause human infection. In remote Indigenous communities of Australia, giardiasis is highly prevalent among children but disease transmission is poorly understood. This study investigated the prevalence of Giardia and genetic subtypes contributing to human disease in a remote Indigenous community, in the Northern Territory of Australia. Eighty-seven faecal samples were collected from 74 children (<15 years) over an 18 month period, and the distribution of positive cases relative to participant age and gender were examined. Screening by microscopy and 18S rRNA PCR amplification showed 66.7% (58/87) of faecal samples were positive for Giardia. Both males and females were equally affected and high detection rates were obtained for participants aged 0–<5 years and 5–<10 years (66.0 and 60.0% respectively). For 58.6% of the positive samples, Giardia was only detected by 18S rRNA PCR. Approximately 75% of cases were assemblage B, and subassemblage analyses using terminal restriction fragment length polymorphism of the glutamate dehydrogenase gene demonstrated that a variety of genetic variants were present. The high proportion of positive cases that were not detectable by microscopy, and dominance of assemblage B cases highlights the need for further research in this community, to assess the contribution of Giardia to chronic gastrointestinal disease among children, and to understand conditions conductive to assemblage B transmission.     

Alien plants in central Australia

The central Australian flora currently contains 78 alien species, of which 17 are predominantly summer-growing, 19 are southern winter-growing species reaching roadsides, stockyards and watercourses in the southern Northern Territory and 42 are at present confined to gardens in Alice Springs. A further 11 species reach the far north of South Australia or die far southwest of Queensland but not the Northern Territory. The central Australian alien flora may be classified by growing season and drought-tolerance, or broadly categorized on the basis of habitat and dispersal agent into 'garden weeds', 'tourist weeds' and 'stock weeds'. Present ecological knowledge of central Australian aliens is limited, but indicates that whilst some will probably remain confined to better-watered habitats, many are likely to spread into the arid areas, becoming obvious only after a succession of wet years. The central Australian alien flora is increasing at present and this increase is expected to continue.     

A new species of Macrobrachium (Decapoda, Caridea, Palaemonidae) from Northern Territory, Australia and a key to Australian species of the genus

A new species of freshwater prawn Macrobrachium bullatum sp.n. is described from the Alligator Rivers region of Northern Territory, Australia. The cutting edges of fingers of chelipeds (pereiopod 2) have rows of six opposing, equally spaced, large horny tubercles, interspersed between rows of stiff hairs. A key to Australian species of the genus Macrobrachium is also given.     

Isolation and characterisation of a novel Bohle-like virus from two frog species in the Darwin rural area, Australia

Twelve captive magnificent tree frogs Litoria splendida and 2 green tree frogs L. caerulea on a property in the Darwin rural area (Northern Territory, Australia) either died or were euthanased after becoming lethargic or developing skin lesions. Samples from both species of frog were submitted for histopathology and virus isolation. An irido-like virus was cultured from tissue samples taken from both species and was characterised using electron microscopy, restriction enzyme digests and nucleic acid amplification and sequencing. The isolates were determined to belong to the genus Ranavirus, were indistinguishable from each other and shared a 98.62% nucleotide similarity and a 97.32% deduced amino acid homology with the Bohle iridovirus over a 1161 bp region of the major capsid gene. This is the first isolation of a ranavirus from amphibians in the Northern Territory and the first report of natural infection in these 2 species of native frog. The virus is tentatively named Mahaffey Road virus (MHRV).     

A new species of the genus Hydrodroma Koch, 1837 (Acari, Hydrachnidia, Hydrodromidae), with a key to the hitherto known six species of the genus in Australia

The genus Hydrodroma Koch, 1837 in Australia consists of six species, the newly described Hydrodroma meridionalissp. n. included. The new species is described from 45 sampling sites from running waters in Queensland, Victoria, New Southern Wales, Western Australia, Northern Territory and South Australia. Furthermore, a key for the identification of species of Hydrodroma occurring in Australia is given.     

Health care cost of crusted scabies in Aboriginal communities in the Northern Territory,Australia

BackgroundCrusted scabies is a debilitating dermatological condition. Although still relatively rare in the urban areas of Australia, rates of crusted scabies in remote Aboriginal communities in the Northern Territory (NT) are reported to be among the highest in the world.ObjectiveTo estimate the health system costs associated with diagnosing, treating and managing crusted scabies.MethodsA disease pathway model was developed to identify the major phases of managing crusted scabies. In recognition of the higher resource use required to treat more severe cases, the pathway differentiates between crusted scabies severity grades. The disease pathway model was populated with data from a clinical audit of 42 crusted scabies patients diagnosed in the Top-End of Australia’s Northern Territory between July 1, 2016 and May 1, 2018. These data were combined with standard Australian unit costs to calculate the expected costs per patient over a 12-month period, as well as the overall population cost for treating crusted scabies.FindingsThe expected health care cost per patient diagnosed with crusted scabies is $35,418 Australian dollars (AUD) (95% CI: $27,000 to $43,800), resulting in an overall cost of $1,558,392AUD (95% CI: $1,188,000 to $1,927,200) for managing all patients diagnosed in the Northern Territory in a given year (2018). By far, the biggest component of the health care costs falls on the hospital system.DiscussionThis is the first cost-of-illness analysis for treating crusted scabies. Such analysis will be of value to policy makers and researchers by informing future evaluations of crusted scabies prevention programs and resource allocation decisions. Further research is needed on the wider costs of crusted scabies including non-financial impacts such as the loss in quality of life as well as the burden of care and loss of well-being for patients, families and communities.     

Breeding system, colony and population structure in the weaver ant Oecophylla smaragdina

Weaver ants ( Oecophylla smaragdina ) are dominant ants in open forests from India, Australia, China and Southeast Asia, whose leaf nests are held together with larval silk. The species, together with its sole congener O. longinoda , has been important in research on biological control, communication, territoriality and colony integration. Over most of the range, only one queen has been found per colony, but the occurrence of several queens per nest has been reported for the Australian Northern Territory. The number of males mating with each queen is little known. Here we report on the colony structure of O. smaragdina using published and new microsatellite markers. Worker genotype arrays reflect the occurrence of habitual polygyny (more than one queen per colony) in 18 colonies from Darwin, Northern Australia, with up to five queens inferred per colony. Monogyny (one queen per colony) with occasional polygyny was inferred for 14 colonies from Queensland, Australia, and 20 colonies from Java, Indonesia. Direct genotyping of the sperm carried by 77 Queensland queens and worker genotypic arrays of established colonies yielded similar results, indicating that less than half of the queens mate only once and some mate up to five times. Worker genotype arrays indicated that queens from Java and the Northern Territory also often mate with more than one male, but less often than those from Queensland. A strong isolation-by-distance effect was found for Queensland samples. The variation uncovered means that O. smaragdina is a more versatile study system than previously supposed.