Diversity and distribution patterns in high southern latitude sponges

Sponges play a key role in Antarctic marine benthic community structure and dynamics and are often a dominant component of many Southern Ocean benthic communities. Understanding the drivers of sponge distribution in Antarctica enables us to understand many of general benthic biodiversity patterns in the region. The sponges of the Antarctic and neighbouring oceanographic regions were assessed for species richness and biogeographic patterns using over 8,800 distribution records. Species-rich regions include the Antarctic Peninsula, South Shetland Islands, South Georgia, Eastern Weddell Sea, Kerguelen Plateau, Falkland Islands and north New Zealand. Sampling intensity varied greatly within the study area, with sampling hotspots found at the Antarctic Peninsula, South Georgia, north New Zealand and Tierra del Fuego, with limited sampling in the Bellingshausen and Amundsen seas in the Southern Ocean. In contrast to previous studies we found that eurybathy and circumpolar distributions are important but not dominant characteristics in Antarctic sponges. Overall Antarctic sponge species endemism is ～43%, with a higher level for the class Hexactinellida (68%). Endemism levels are lower than previous estimates, but still indicate the importance of the Polar Front in isolating the Southern Ocean fauna. Nineteen distinct sponge distribution patterns were found, ranging from regional endemics to cosmopolitan species. A single, distinct Antarctic demosponge fauna is found to encompass all areas within the Polar Front, and the sub-Antarctic regions of the Kerguelen Plateau and Macquarie Island. Biogeographical analyses indicate stronger faunal links between Antarctica and South America, with little evidence of links between Antarctica and South Africa, Southern Australia or New Zealand. We conclude that the biogeographic and species distribution patterns observed are largely driven by the Antarctic Circumpolar Current and the timing of past continent connectivity.     

Barging in: A Temperate Marine Community Travels to the Subantarctic

A diverse fouling community discovered encrusting a barge intended for deployment at subantarctic Macquarie Island is described and its role as a transport vector for non-indigenous marine organisms is discussed. The barge proved to be a potential vector capable of transporting entire epi-bethic communities, 20 species in total, from a temperate estuarine system (Derwent River, Tasmania, Australia) into the subantarctic. For one invasive amphipod species Monocorophium acherusicum, over 136000 individuals including ovigerous females were calculated to be associated with the barge fouling community. Although distinct differences exist between the thermal ranges of Macquarie Island and the Bruny bioregion of Tasmania, a hazard assessment based on the Gower similarity coefficient suggested sufficient similarity between the two environments to allow for survival of transported organisms for eight months of the year. Several invasive species are able to survive the thermal conditions of the subantarctic irrespective of the time of year. This study identifies the need for effective quarantine measures aimed at identifying and managing marine biosecurity hazards in association with human activities in high latitude regions.     

Biogeographic patterns in the Australian chondrichthyan fauna

The major biogeographic structure and affinities of the Australian chondrichthyan fauna were investigated at both interregional and intraregional scales and comparisons made with adjacent bioregions. Faunal lists were compiled from six geographical regions with species from these regions assigned to distributional classes and broad habitat categories. Australian species were further classified on provincial and bathomic structure following bioregionalization outputs from regional marine planning. About 40% of the world's chondrichthyan fauna occurs in Indo-Australasia (482 species) of which 323 species are found in Australian seas. The tropical Australian component, of which c. 46% of taxa are regional endemics, is most similar to faunas of Indonesia, New Guinea and New Caledonia. The temperate Australian component is most similar to New Zealand and Antarctica with about half of its species endemic. Highest levels of Australian endemism exist in bathomes of the outer continental shelf and upper slope. A relatively high proportion of regional endemism (57% of species) on the slope in the poorly surveyed but species-rich Solanderian unit is probably due to high levels of large-scale habitat complexity in the Coral Sea. The richness of demersal assemblages on the continental shelf and slope appears to be largely related to the spatial complexity of the region and the level of exploration. Much lower diversity off Antarctica is consistent with the pattern in teleosts. The complex chondrichthyan fauna of Australia is confirmed as being amongst the richest of the mega-diverse Indo-West Pacific Ocean. Species-level compositions of regional faunas across Indo-Australasia differ markedly because of moderate to high levels of intraregional speciation. Faunal assemblages in Australian marine provinces and bathomes differ from each other, supporting a broader pattern for fishes that underpins a marine planning framework for the region.     

Proceedings of the SMBE Tri-National Young Investigators' Workshop 2005. Southern hemisphere springtails: could any have survived glaciation of Antarctica?

Throughout the Southern Hemisphere many terrestrial taxa have circum-Antarctic distributions. This pattern is generally attributed to ongoing dispersal (by wind, water, or migrating birds) or relict Gondwanan distributions. Few of these terrestrial taxa have extant representatives in Antarctica, but such taxa would contribute to our understanding of the evolutionary origins of the continental Antarctic fauna. Either these taxa have survived the harsh climate cooling in Antarctica over the last 23 Myr (Gondwanan/vicariance origin) or they have dispersed there more recently (<2 MYA). In this context, we examined mtDNA (COI) sequence variation in Cryptopygus and related extant Antarctic and subantarctic terrestrial springtails (Collembola). Sequence divergence was estimated under a maximum likelihood model (general time reversible+I+Gamma) between individuals from subantarctic islands, Australia, New Zealand, Patagonia, Antarctic Peninsula, and continental Antarctica. Recent dispersal/colonization (<2 MYA) of Cryptopygus species was inferred between some subantarctic islands, and there was a close association between estimated times of divergences based on a molecular clock and proposed geological ages of islands. Most lineages generally grouped according to geographic proximity or by inferred dispersal/colonization pathways. In contrast, the deep divergences found for the four endemic Antarctic species indicate that they represent a continuous chain of descent dating from the break up of Gondwana to the present. We suggest that the diversification of these springtail species (21-11 MYA) in ice-free glacial refugia throughout the Trans-Antarctic Mountains was caused by the glaciation of the Antarctic continent during the middle to late Miocene.     

New Zealand's pteridophyte flora—Plants of ancient lineage but recent arrival?

A hypothesis is presented that most pteridophytes arrived in New Zealand relatively recently, by long-distance dispersal. The flora comprises 194 native species, of which 89 (46%) are endemic and 105 (54%) are widespread. Of the latter, 90% are shared with temperate Australasia, 53% with tropical regions, 14% with temperate southern Africa and 13% with the circum-Antarctic islands and South America. New Zealand has undergone such dramatic changes in location, land area, and topography since initial separation from Gondwana 85 Ma that it seems improbable that the 95 species shared with temperate Australasia could have remained conspecific throughout that time. Modern fossil and molecular evidence strongly suggest that many families of ferns had not even evolved prior to separation, and palynological evidence from New Zealand indicates that 78% of pteridophyte genera first appeared there only after separation from Gondwana. Present-day distributions in New Zealand suggest that ferns have greater dispersal potential than flowering plants, and that pteridophyte distributions are more heavily influenced by temperature, rainfall, and geothermal activity than by geological history. Most endemic pteridophyte species have a predominantly southern distribution pattern and are characteristic of cool, lowland to montane forest. Pteridophytes in the northern part of New Zealand show a lower level of endemism than elsewhere and tend to be widespread species that have arrived from temperate Australasian and tropical regions. There is also evidence that at least some pteridophytes have migrated from New Zealand to Australia. It is suggested that the hypothesis of long-distance dispersal of pteridophytes across the Tasman Sea could be tested by molecular techniques.     

Long distance migration of insects to a subantarctic island

Transoceanic migration of four species of macrolepidoptera to subantarctic Macquarie Island has been detected in 7 out of 33 years during the period 1962–96 and is restricted to spring and autumn. Analyses of synoptic charts during the migration period show that autumn immigrants originated from New Zealand and comprised a single species of noctuid moth,Agrotis ipsilon (Walker). Spring immigrants originated from Australia and comprised two noctuids, Dasypodia selenophora Guenée and Persectania ewingii Westwood and a butterfly, Vanessa kershawi (McCoy). Autumn migrations were associated with depressions in the southern Tasman Sea. Spring migrations were associated with the eastward passage of prefrontal airflows ahead of cold fronts which extended from southern Australia to the west of Macquarie Island. In an analysis of one of these events, winds exceeded 30 ms^?1 at 300 m altitude and could have transported migrants from Tasmania to Macquarie Island overnight in less than 10 h. Flight activity was assisted by the presence of a nocturnal temperature inversion that maintained upper air temperatures above 5 °C. The effect of potential global warming on the migration and colonization of Macquarie Island by insects is discussed.     

Fur seals at Macquarie Island: post-sealing colonisation,trends in abundance and hybridisation of three species

Commercial sealers exterminated the original fur seal population at Macquarie Island in the early 1800s. The first breeding record since the sealing era was not reported until March 1955. Three species of fur seal now occur at Macquarie Island, the Antarctic (Arctocephalus gazella), subantarctic (A. tropicalis) and New Zealand (A. forsteri) fur seal. Census data from 54 breeding seasons in the period 1954–2007 were used to estimate population status and growth for each species. Between the 1950s and 1970s, annual increases in pup production for the species aggregate were low. Between 1986 and 2007, pup production of Antarctic fur seals increased by about 8.8% per year and subantarctic fur seals by 6.8% per year. The New Zealand fur seal, although the most numerous fur seal species on Macquarie Island, has yet to establish a breeding population, due to the absence of reproductively mature females. Hybridisation among species is significant, but appears to be declining. The slow establishment and growth of fur seal populations on Macquarie Island appears to have been affected by its distance from major population centres and hence low immigration rates, asynchronous colonisation times of males and females of each species, and extensive hybridisation.     

The first record of a terrestrial landhopper (Crustacea: Amphipoda: Talitridae) from Macquarie Island

A terrestrial talitrid crustacean is recorded for the first time from subantarctic Macquarie Island. The species, Puhuruhuru patersoni, is native to the southern part of the South Island of New Zealand. Its distribution on Macquarie Is. is restricted to a single locality near the ANARE station on the Isthmus. All mature females collected in December were carrying eggs; females appeared to be less mobile than males. It seems likely that the species has been transported accidentally from New Zealand, perhaps by the same means that introduced the isopod, Styloniscus otakensis, also from southern New Zealand.     

Zoogeography and relationships of Australasian skates (Chondrichthyes: Rajidae)

Aim To investigate distributional patterns and derivation of skates in the Australasian realm. Location Australasia. Methods Genus‐group skate taxa were defined for this region for the first time and new systematic information, as well as bathymetric and geographical data, used to identify distribution patterns. Results The extant skate fauna of Australasia (Australia, New Zealand, New Caledonia and adjacent subAntarctic dependencies) is highly diverse and endemic with sixty‐two species from twelve currently recognized, nominal genus‐group taxa. These include the hardnose skate (rajin) groups Anacanthobatis, Amblyraja, Dipturus, Okamejei, Rajella and Leucoraja, and softnose skate (arhynchobatin) genera Arhynchobatis, Bathyraja, Insentiraja, Irolita, Pavoraja and Notoraja. Additional new and currently unrecognized nominal taxa of both specific and supraspecific ranks also occur in the region. The subfamily Arhynchobatinae is particularly speciose in Australasia, and the New Zealand/New Caledonian fauna is dominated by undescribed supraspecific taxa and species. The Australian fauna, although well represented by arhynchobatins, is dominated by Dipturus‐like skates and shows little overlap in species composition with the fauna of New Zealand and New Caledonia. Similarly, these faunas exhibit no overlap with the polar faunas of the Australian subAntarctic dependencies (Heard and Macdonald Islands) to the south. Skates appear to be absent from the Macquarie Ridge at the southern margin of the New Zealand Plateau. Their absence off New Guinea probably reflects inadequate sampling and the subsequent poor knowledge of that region's deepwater fish fauna. Main conclusions Skates appear to have existed in the eastern, Australasian sector of Gondwana before fragmentation in the late Cretaceous. The extant fauna appears to be derived from elements of Gondwanan origin, dispersal from the eastern and western Tethys Sea, and intraregional vicariance speciation.     

Biology and molecular phylogenetics of Nematoceras sulcatum, a second endemic orchid species from subantarctic Macquarie Island

A second orchid species, Nematoceras sulcatum M.A.Clem. et D.L.Jones, has been found on subantarctic Macquarie Island. A history of its discovery and recognition is provided. The morphology, biology and ecology of the new species are compared with N. dienemum (D.L.Jones) D.L.Jones, M.A.Clem. et Molloy, the other species of orchid on Macquarie Island. Molecular studies based on the internal transcribed spacer (ITS) region of nuclear ribosomal DNA reveal the phylogenetic relationship of the two Macquarie Island species compared to others in the genus from New Zealand and its Southern Ocean islands.     

Ménage à trois on Macquarie Island: hybridization among three species of fur seal (Arctocephalus spp.) following historical population extinction

Human-induced changes to natural systems can cause major disturbances to fundamental ecological and population processes and result in local extinctions and secondary contacts between formerly isolated species. Extensive fur seal harvesting during the nineteenth century on Macquarie Island (subantarctic) resulted in extinction of the original population. Recolonization by three species has been slow and complex, characterized by the establishment of breeding groups of Antarctic and subantarctic fur seals (Arctocephalus gazella and Arctocephalus tropicalis) and presumed nonbreeding (itinerant) male New Zealand fur seals (Arctocephalus forsteri). One thousand and seven pups from eight annual cohorts (1992-2003) were analysed using mitochondrial control region data (RFLP) and 10 microsatellite loci to estimate species composition and hybridization. Antarctic fur seals predominated, but hybridization occurred between all three species (17-30% of all pups). Involvement of New Zealand fur seals was unexpected as females are absent and males are not observed to hold territories during the breeding season. The proportion of hybrids in the population has fallen over time, apparently owing to substantial influxes of pure Antarctic and subantarctic individuals and non-random mating. Over 50% of New Zealand hybrids and 43% of Antarctic-subantarctic hybrids were not F(1), which indicates some degree of hybrid reproductive success, and this may be underestimated: simulations showed that hybrids become virtually undetectable by the third generation of backcrossing. While human impacts seem to have driven novel hybridization in this population, the present 'time slices' analysis suggests some biological resistance to complete homogenization.     

A new model Gondwanan taxon: systematics and biogeography of the harvestman family Pettalidae (Arachnida, Opiliones, Cyphophthalmi), with a taxonomic revision of genera from Australia and New Zealand

The phylogeny of the temperate Gondwanan harvestman family Pettalidae is investigated by means of a new morphological matrix of 45 characters, and DNA sequence data from five markers, including two nuclear ribosomal genes (18S rRNA and 28S rRNA), one nuclear protein coding gene (histone H3), and two mitochondrial genes–one protein coding (cytochrome c oxidase subunit I) and one ribosomal (16S rRNA). Phylogenetic analyses using an array of homology schemes (dynamic and static), criteria (parsimony and maximum likelihood), and sampling strategies (optimal trees versus Bayesian phylogenetics) all agree on the monophyly of Pettalidae as well as several of its subclades, each of which is restricted to a modern landmass. While most genera as traditionally defined are monophyletic, Rakaia and Neopurcellia, distributed across Queensland (Australia) and New Zealand, are not. Instead, the species from Queensland, previously described under three genera, constitute a well‐supported clade, suggesting that in this case biogeography prevails over traditional taxonomy. A taxonomic emendation of the genera from Queensland and New Zealand is presented, and the new genus Aoraki is erected to include the species of the New Zealand denticulata group. A biogeographical hypothesis of the relationships of the former temperate Gondwana landmasses (with the exception of Madagascar) is presented, although ambiguity in the deep nodes of the pettalid tree renders such inference provisional. The data suggest that neither the South African fauna, the New Zealand fauna nor the Australian fauna is monophyletic but instead monophyly is found at smaller geographic scales (e.g., Western Australia, Queensland, NE South Africa). © The Willi Hennig Society 2007.     

East meets west: biogeology of the Campbell Plateau

The New Zealand Subantarctic Islands, emergent remnants of the Campbell Plateau, were given World Heritage status in 1998 in recognition of their importance to global biodiversity. We describe the flora and fauna of these islands and discuss the results of recent phylogenetic analyses. Part of the New Zealand Subantarctic biota appears to be relictual and to be derived from west Gondwana. The relictual element is characterized by genera endemic to the Campbell Plateau that show relationships with taxa of the southern South Island, New Zealand, southern South America, and the north Pacific. In contrast, a younger, east Gondwanan element is composed of species that are either taxonomically identical to widespread mainland species, or endemic species with close New Zealand relatives. Area cladograms support the inclusion of the southern South Island, New Zealand and Macquarie Island (although this is separate geologically) as parts of the Campbell Plateau, but suggest the Chatham Rise and Torlesse terranes of the eastern South Island, New Zealand were originally parts of east Gondwana. East and west Antarctica acted as independent plates during the breakup of Gondwana, and were separated by oceanic crust until a compressive phase sutured them along the trace of the trans‐Antarctic mountains during the early Tertiary. The Campbell Plateau microcontinent was connected to west Antarctica until its separation at 80 Mya, contemporaneous with the separation of the southern portion of the Melanesian rift from east Gondwana. Presently the Campbell Plateau is joined to the Melanesian Rift along the Alpine Fault. Cenozoic plate tectonic reconstructions place the Campbell Plateau adjacent to the Melanesian Rift throughout the rift–drift phase, relative motion being confined to strike–slip movement over the last 20 Myr. Our synthesis of phylogenetic and plate tectonic evidence suggests that the Alpine Fault is the most recent development of a much older extensional rift/basin boundary originally separating west and east Gondwana. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 86 , 95–115.     

Cold‐water coral habitats on seamounts: do they have a specialist fauna?

Aim The large biogenic structures formed by colonial cold‐water scleractinian corals provide valuable habitat for marine invertebrates on seamounts and the continental slope of all world oceans. These patchily distributed long‐lived structures are easily damaged by several human activities, particularly bottom trawling for fish, and are potentially vulnerable to ocean acidification caused by climate change. Consequently, an important conservation question is whether these structures support a specialized invertebrate fauna restricted to these habitats. Here we investigate the relationship between structures formed by the coral Solenosmilia variabilis and its associated ophiuroid (brittlestar) fauna, one of the dominant components of deep‐sea ecosystems. Location Seafloor habitat around Southern Australia, New Zealand, and the Macquarie Ridge from 35 to 53° S and 117° E–176° W, 500–1500 m depth. Methods Data were derived from samples collected by numerous scientific expeditions to the study region. Because these samples were collected using a variety of gear and effort, a two‐step approach was used. First, the largest consistently collected data set (73 ophiuroid species from 59 samples) was assembled for multivariate analysis. ANOSIM was used to test for differences in ophiuroid community composition between Solenosmilia and non‐Solenosmilia habitat on seamounts and the continental slope, and SIMPER was used to identify species that characterized Solenosmilia habitat. Second, these results were validated against all known data to ensure that these characteristic species had not been found in non‐Solenosmilia habitat elsewhere. Results The ophiuroid assemblages from Solenosmilia habitat were distinct from those found on other habitats on the continental slope and offshore seamounts across the study region. Although a suite of ophiuroid species characterized Solenosmilia habitat, most have also been collected from dead coral or other rubble, suggesting a physical rather than biological association between the coral matrix and its associated invertebrate fauna. Main conclusions Despite the lack of an exclusive ophiuroid–coral relationship, cold‐water scleractinian coral remains the principal habitat for a number of ophiuroid species across southern Australia and New Zealand. The slow growth rate of the coral and the low dispersal potential of some associated species suggest that recovery of damaged cold‐water coral assemblages will be a long‐term process.     

Biogeographic traits and checklist of Antarctic demosponges

Summary The biogeography of Antarctic demosponges has been studied by dividing Antarctic and circumantarctic areas into geographic entities, and then assigning to these entities all recorded species according to literature reports. Correspondence analysis ordination based on the presence or absence of species shows the existence of a distinct Antarctic Faunistic Complex (AFC), including continental Antarctica, most of the Antarctic and circumantarctic islands and the Magellan area. Such a result has enabled us to drawup a checklist of 352 Antarctic demosponge species. Investigation of within-AFC patterns indicates that the continent is a highly homogeneous area, establishing closer relationships with the Scotia Arc and to a lesser extent with the Magellan region. The AFC has low specific affinities with the other circumantarctic regions (South Africa, temperate Australia and New Zealand), whereas at the generic level relationships appear more pronounced. This biogeographic pattern may lead us to suppose a common Gondwanian origin for Antarctic and circumantarctic sponge faunas, followed by differentiation due to Gondwana fragmentation. Antarctica moved towards polar latitudes and became progressively isolated, only maintaining active interchanges with South America. Climatic changes possibly induced intense processes of speciation in the Antarctic demosponge fauna, thus contributing to its differentiation.     

Bivalves in a bottleneck: taxonomy,phylogeography and conservation of freshwater mussels (Bivalvia: Unionoida) in Australasia

The conservation biology of Australasian freshwater mussels is hindered by lack of a taxonomic framework that employs molecular data as a complement to shell characters, larval forms and internal anatomy. The fauna includes more than 32 known species (30+ Hyriidae, 2 Unionidae), but has not been revised for 55 years, despite minor amendments. The hyriids are relics of Gondwana, represented in Australia and New Guinea by the ancestral Velesunioninae and in Australia and New Zealand by the Hyriinae (Tribe Hyridellini). Many taxonomic and phylogeographic issues await resolution, including the relationships between Australasian and South American species, and between Australian and New Zealand species, and the status of species in New Guinea (including uncertain reports of Unionidae) and the Solomon Islands. Once these are clarified, it will be easier to identify threatened species and evaluate the conservation status of the fauna. At present, only seven taxa are named in the IUCN Red List or under national/state legislation, and these are not representative. Threatening processes include altered flow regimes, catchment disturbances, salinisation, pollution and invasive species. While the need for a taxonomic revision is paramount, progress in conservation may depend also upon involving the wider community.     

Distribution patterns and biogeographic analysis of Austral Polychaeta (Annelida)

Aim We investigate the biogeography of Austral Polychaeta (Annelida) using members of the families Eunicidae, Lumbrineridae, Oenonidae, Onuphidae, Serpulidae and Spionidae and Parsimony Analysis of Endemicity (PAE). We determine whether observed polychaete distribution patterns correspond to traditional shallow-water marine areas of endemism, estimate patterns of endemism and relationships between areas of endemism, and infer the biological processes that have caused these patterns. Location The study is concerned with extant polychaete taxa occupying shallow-water areas derived from the breakup of the Gondwana landmass (i.e. Austral areas). Methods Similarity was assessed using a significance test with Jaccard's indices. Areas not significantly different at 0.99 were combined prior to the PAE. Widespread species and genera (155 taxa) were scored for presence/absence for each area of endemism. PAE was used to derive hypotheses of area relationships. Hierarchical patterns in the PAE trees were identified by testing for congruence with patterns derived from cladistic biogeographic studies of other Gondwanan taxa and with geological evidence. Results The polychaete faunas of four area-pairs were not significantly different and the areas amalgamated: South-west Africa and South Africa, New Zealand South Island and Chatham Islands, Macquarie Island and Antipodean Islands, and West Antarctica and South Georgia. Areas with the highest levels of species endemism were southern Australia (67.0%), South-east South America (53.2%) and South Africa (40.4%). About 60% of species and 7.5% of genera occupied a single area of endemism. The remainder were informative in the PAE. Under a no long-distance dispersal assumption a single minimal-length PAE tree resulted (l=367; ci=0.42); under dispersal allowed, three minimal-length trees resulted (l=278; ci=0.56). In relation to the sister grouping of the New Zealand areas and Australia we find congruence between our minimal-length trees and those derived from a biogeographic study of land plants, and with area relationships predicted by the Expanding Earth Model. Main conclusions The polychaete distribution patterns in this study differ slightly from the classical areas of endemism, most notably in being broader, thereby bringing into question the value of using single provincial system for marine biogeographic studies. The Greater New Zealand region is found to be ‘monophyletic’ with respect to polychaetes, that is comprising a genuine biogeographical entity, and most closely related to the polychaete fauna of southern Australia. This finding is consistent with studies of land plants and with the Expanding Earth model, but disagrees with conventional geology and biogeographic hypothesis involving a ‘polyphyletic’ New Zealand. Both vicariance and concerted range expansion (=biotic dispersion) appear to have played important roles in shaping present-day distribution patterns of Austral polychaetes. Shallow-water ridge systems between the Australian and Greater New Zealand continental landmasses during the Tertiary are thought to have facilitated biotic dispersion.     

Moss biogeography in the Tasman Sea region

Abstract

Panbiogeographic track analysis is applied to the distribution of several groups of mosses which occur in the New Zealand region. The analysis highlights areas of biogeographic interest (nodes) in the New Zealand region as follows: 1. New Guinea, 2. New Caledonia, 3. New South Wales/Queensland border in Australia, 4. northern New Zealand, 5. Rapa Island, 6. subantarctic New Zealand.

New Zealand is connected to these nodes by the following standard tracks: 1. New Guinea—New South Wales/Queensland border—Tasmania—subantarctic New Zealand, 2. New Guinea—New Caledonia—New Zealand—subantarctic New Zealand, 3. a central Tasman Sea transversal track; New South Wales/Queensland border—New Caledonia. Rapa Island is connected to the Tasman region by northern New Zealand and New Caledonia.     

Invasion of two exotic terrestrial flatworms to subantarctic Macquarie Island

Invasive species are a serious threat to biodiversity worldwide. The relatively simple ecological systems of the subantarctic have the potential to be significantly damaged by predatory species that invade. Two species of exotic, predatory, terrestrial flatworms were first collected in 1997 from two localities only 2 km apart, in the southeast of subantarctic Macquarie Island. The species were later identified as Kontikia andersoni and Arthurdendyus vegrandis. We report here the results of fieldwork in 2004 that established that both species now occupy about a seventh of the southeast of the island which has a total area of only 170 km² and that there seem to be no barriers to further expansion. The island was first discovered in 1810 and so it is likely the species were introduced by means of human intervention within the last 200 years. We provide evidence to show that both species originated in New Zealand and have probably been on the island for ∼100 years giving an average rate of spread of about 10 m per year. Other species of Arthurdendyus have been introduced from New Zealand to the United Kingdom where they prey on earthworms. The quarantine significance of A. vegrandis for Australia is discussed and recommendations made to reduce the probability of it entering Tasmania where it has the potential to become an agricultural pest.