Barbara York Main

Deep phylogeographic structuring of populations of the trapdoor spider Moggridgea tingle (Migidae) from southwestern Australia: evidence for long-term refugia within refugia

Southwestern Australia has been recognized as a biodiversity hot spot of global significance, and it is particularly well known for its considerable diversity of flowering plant species. Questions of interest are how this region became so diverse and whether its fauna show similar diverse patterns of speciation. Here, we carried out a phylogeographic study of trapdoor spiders (Migidae: Moggridgea), a presumed Gondwanan lineage found in wet forest localities across southwestern Australia. Phylogenetic, molecular clock and population genetic analyses of mitochondrial (mtDNA) COI gene and ITS rRNA (internal transcribed spacer) data revealed considerable phylogeographic structuring of Moggridgea populations, with evidence for long‐term (>3 million years) isolation of at least nine populations in different geographic locations, including upland regions of the Stirling and Porongurup Ranges. High levels of mtDNA divergence and no evidence of recent mitochondrial gene flow among valley populations of the Stirling Range suggest that individual valleys have acted as refugia for the spiders throughout the Pleistocene. Our findings support the hypothesis that climate change, particularly the aridification of Australia after the late Miocene, and the topography of the landscape, which allowed persistence of moist habitats, have been major drivers of speciation in southwestern Australia.

Predicting the post‐fire responses of animal assemblages: testing a trait‐based approach using spiders

1. Developing a predictive understanding of how species assemblages respond to fire is a key conservation goal. In moving from solely describing patterns following fire to predicting changes, plant ecologists have successfully elucidated generalizations based on functional traits. Using species traits might also allow better predictions for fauna, but there are few empirical tests of this approach. 2. We examined whether species traits changed with post-fire age for spiders in 27 sites, representing a chronosequence of 0-20 years post-fire. We predicted a priori whether spiders with ten traits associated with survival, dispersal, reproduction, resource-utilization and microhabitat occupation would increase or decrease with post-fire age. We then tested these predictions using a direct (fourth-corner on individual traits and composite traits) and an indirect (emergent groups) approach, comparing the benefits of each and also examining the degree to which traits were intercorrelated. 3. For the seven individual traits that were significant, three followed predictions (body size, abundance of burrow ambushers and burrowers was greater in recently burnt sites); two were opposite (species with heavy sclerotisation of the cephalothorax and longer time to maturity were in greater abundance in long unburnt and recently burnt sites respectively); and two displayed response patterns more complex than predicted (abdominal scutes displayed a U-shaped response and dispersal ability a hump shaped curve). However, within a given trait, there were few significant differences among post-fire ages. 4. Several traits were intercorrelated and scores based on composite traits used in a fourth-corner analysis found significant patterns, but slightly different to those using individual traits. Changes in abundance with post-fire age were significant for three of the five emergent groups. The fourth-corner analysis yielded more detailed results, but overall we consider the two approaches complementary. 5. While we found significant differences in traits with post-fire age, our results suggest that a trait-based approach may not increase predictive power, at least for the assemblages of spiders we studied. That said, there are many refinements to faunal traits that could increase predictive power.

Occurrence of the trapdoor spider genus Moggridgea in Australia with descriptions of two new species (Araneae: Mygalomorphae: Migidae)

The occurrence of the trapdoor spider genus Moggridgea (Migidae) in Australia is reported, and two new species described: M. tingle n. sp. from southwest Western Australia and M. australis n. sp. from Kangaroo Island, South Australia. This is the first record of the subfamily Paramiginae from Australia. The historical biogeographic implications are discussed.

Historical ecology, responses to current ecological changes and conservation of Australian spiders

In response to geohistorical events from the Mesozoic through the Tertiary with contraction of mesic forest to southwestern and eastern montane and coastal regions, and expansion of woodlands and xeric shrublands, nobreak Australian spiders today comprise relict families and genera (confined to Gondwanan habitats and refuges) along with later evolved representatives which have adapted to changing environments. Tropical relicts also persist in refugia in the arid interior while some spiders (both mygalomorphs and araneomorphs) have adapted to arid conditions, mainly through specialized behaviours. Although fire has become increasingly a phenomenon of the Australian environment it is doubtful whether any spiders are adapted to fire per se. European settlement has impacted differentially on relictual and later evolved representatives; a few species, including the funnelweb (Atraxrobustus) and redback spider (Latrodectus hasselti) have benefited through enhanced habitat opportunities and some species of Badumna and other genera have become synanthropic. It is suggested that conservation strategies need to consider the ecoevolutionary history of particular spiders and their natural vulnerability or resilience to environmental factors.In response to geohistorical events from the Mesozoic through the Tertiary with contraction of mesic forest to southwestern and eastern montane and coastal regions, and expansion of woodlands and xeric shrublands, nobreak Australian spiders today comprise relict families and genera (confined to Gondwanan habitats and refuges) along with later evolved representatives which have adapted to changing environments. Tropical relicts also persist in refugia in the arid interior while some spiders (both mygalomorphs and araneomorphs) have adapted to arid conditions, mainly through specialized behaviours. Although fire has become increasingly a phenomenon of the Australian environment it is doubtful whether any spiders are adapted to fire per se. European settlement has impacted differentially on relictual and later evolved representatives; a few species, including the funnelweb (Atrax robustus) and redback spider (Latrodectus hasselti) have benefited through enhanced habitat opportunities and some species of Badumna and other genera have become synanthropic. It is suggested that conservation strategies need to consider the ecoevolutionary history of particular spiders and their natural vulnerability or resilience to environmental factors.

Biological anachronisms among trapdoor spiders reflect Australia's environmental changes since the Mesozoic

Mygalomorph spiders have radiated within Australia in response to geocllmatic changes. Relicts are arbitrarily aged in relation to the geological history of the sites in which they occur and their affinity with microhabitats, which are postulated as mimicking lost Mesozoic and early Tertiary biological landscapes. Against the geo-historical background of the south-west Australian landscape, selected trapdoor spiders from the ten relictual genera are discussed in the context of five focal areas. It is suggested that the taxonomic relicts are biological anachronisms, some of which have persisted relatively unmodified beyond the decline of the landscapes In which they evolved. Some relicts are vulnerable to current hazards including fire while others appear to be able to withstand them through behavioural avoidance. The contrast in survival capabilities is presented between Moggrldgea (a Jurassic relict with African affinity) and Neohomogona (a Cretaceous relict which has affinities with eastern Australian mesophytic forest representatives). Conservation of relict mygalomorph taxa must (a) take note of the poor dispersal powers of most species (b) maximize retention of favourable microhabitats and (c) recognize their vulnerability to frequent fire.

Thermal and hygric physiology of Australian burrowing mygalomorph spiders (Aganippe spp.).

This study investigated the standard metabolic rate (SMR) and evaporative water loss (EWL) responses of three Australian trapdoor-constructing mygalomorph spider species, two undescribed arid-zone species (Aganippe ‘Tropicana A’ and A. ‘Tropicana B’) and a mesic-dwelling species (A. rhaphiduca) to acute environmental regimes of temperature and relative humidity. There were significant effects of species, temperature, and relative humidity on SMR. SMR was lower for A. raphiduca than both A. ‘Tropicana’ spp. with no difference between the two A. ‘Tropicana’ spp. Metabolic rate increased at higher temperature and relative humidity for all three species. There were significant effects of species, temperature, and relative humidity on EWL. The mesic Aganippe species had a significantly higher EWL than either arid Tropicana species. EWL was significantly higher at lower relative humidity. Our results suggest an environmental effect on EWL but not SMR, and that mygalomorphs are so vulnerable to desiccation that the burrow provides a crucial refuge to ameliorate the effects of low environmental humidity. We conclude that mygalomorphs are highly susceptible to disturbance, and are of high conservation value as many are short-range endemics.

Where have all the spiders gone? The decline of a poorly known invertebrate fauna in the agricultural and arid zones of southern Australia

Earth is currently experiencing the sixth mass extinction of complex multi‐cellular life, the first at the hands of a single species. The documented extinctions of iconic (mostly vertebrate and plant) taxa dominate the discourse, while poorly known invertebrate species are disappearing ‘silently’, sometimes without having ever been described. Here, we highlight the decline of elements of the trapdoor spider (Mygalomorphae: Idiopidae) fauna of southern Australia – a taxonomically poorly documented yet diverse assemblage of long‐lived fossorial predators. We show that a number of trapdoor spider species may be threatened after a century of intensive land clearing and stocking, and that remaining populations in some areas may be experiencing serious contemporary population declines. So, how do we conserve this fauna? We suggest that baseline systematic studies are crucial, and that follow‐up surveys, including integrative citizen science solutions, should be used to assess where remnant populations still exist, and whether they can persist into the future. Detailed population genetic research on a handful of carefully chosen taxa could be broadly informative, and ongoing natural history studies remain invaluable. Although solutions may be limited in the face of ongoing habitat degradation and other threats, urgently quantifying declines has implications not just for spiders but for mitigating against the mass extinction of poorly known invertebrate taxa across the globe.

Refugia within refugia: in situ speciation and conservation of threatened Bertmainius (Araneae : Migidae), a new genus of relictual trapdoor spiders endemic to the mesic zone of south-western Australia

Abstract. The trapdoor spider family Migidae has a classical Gondwanan distribution and is found on all southern continents except the Indian region. The Australian fauna consists of three genera including Moggridgea O. P. Cambridge from south-western Australia and Kangaroo Island, South Australia; Moggridgea is otherwise widespread throughout Africa. The sole named species of Moggridgea from Western Australia, M. tingle Main, and its unnamed relatives are the subject of the present paper, which was stimulated by concern for the long-term persistence of populations, and the discovery of deep genetic divergences between populations. A phylogeny of the Western Australian species relative to African and South Australian Moggridgea was generated using molecular COI and ITS rDNA data, and based on both molecular and morphological criteria we conclude that the Western Australian taxa should be removed from Moggridgea and transferred to a new genus, Bertmainius. The seven species are delimited using both morphological and molecular criteria: B. tingle (Main) (the type species), and six new species, B. colonus, B. monachus, B. mysticus, B. opimus, B. pandus and B. tumidus. All seven species are considered to be threatened using IUCN criteria, with the major threatening processes being inappropriate fire regimes and climate change.

The Australasian spiny trapdoor spiders of the family Idiopidae (Mygalomorphae : Arbanitinae): a relimitation and revision at the generic level

Abstract. The Australasian spiny trapdoor spiders of the family Idiopidae (subfamily Arbanitinae) are revised at the generic level, using a multi-locus molecular phylogenetic foundation and comprehensive sampling of all known lineages. We propose a new family- and genus-group classification for the monophyletic Australasian fauna, and recognise 10 genera in four tribes. The Arbanitini Simon includes Arbanitis L. Koch, 1874 (61 species), Blakistonia Hogg, 1902 (one species) and Cantuaria Hogg, 1902 (43 species). The Aganippini Simon includes Bungulla Rix, Main, Raven & Harvey, gen. nov. (two species), Eucanippe Rix, Main, Raven & Harvey, gen. nov. (one species), Eucyrtops Pocock, 1897 (two species), Gaius Rainbow, 1914 (one species) and Idiosoma Ausserer, 1871 (14 species). The Cataxiini Rainbow and Euoplini Rainbow include just Cataxia Rainbow, 1914 (11 species) and Euoplos Rainbow, 1914 (12 species), respectively. Two distinctive new genera of Aganippini are described from Western Australia, and several previously valid genera are recognised as junior synonyms of existing genus-group names, including Misgolas Karsch, 1878 (= Arbanitis; new synonymy), Aganippe O. P.-Cambridge, 1877 (= Idiosoma; new synonymy) and Anidiops Pocock, 1897 (= Idiosoma; new synonymy). Gaius stat. rev. is further removed from synonymy of Anidiops. Other previously hypothesised generic synonyms are supported by both morphology and molecular phylogenetic data from 12 genes, including the synonymy of Neohomogona Main, 1985 and Homogona Rainbow, 1914 with Cataxia, and the synonymy of Albaniana Rainbow & Pulleine, 1918, Armadalia Rainbow & Pulleine, 1918, Bancroftiana Rainbow & Pulleine, 1918 and Tambouriniana Rainbow & Pulleine, 1918 with Euoplos. At the species level, the identifications of Eucy. latior (O. P.-Cambridge, 1877) and I. manstridgei (Pocock, 1897) are clarified, and three new species are described: Bungulla bertmaini Rix, Main, Raven & Harvey, sp. nov., Eucanippe bifida Rix, Main, Raven & Harvey, sp. nov. and Idiosoma galeosomoides Rix, Main, Raven & Harvey, sp. nov., the latter remarkable for its phragmotic abdominal morphology. The Tasmanian species Mygale annulipes C. L. Koch, 1842 is here transferred to the genus Stanwellia Rainbow & Pulleine, 1918 (family Nemesiidae), comb. nov., Arbanitis mestoni Hickman, 1928 is transferred to Cantuaria, comb. nov. and Idiosoma hirsutum Main, 1952 is synonymised with I. sigillatum (O. P.-Cambridge, 1870), new synonymy. In addition to the morphological synopses and an illustrated key to genera, molecular diagnoses are presented for all nominal taxa, along with live habitus and burrow images to assist in field identification. The Australasian idiopid fauna is highly diverse, with numerous new species known from all genera. As a result, this study provides a taxonomic and nomenclatural foundation for future species-level analyses, and a single reference point for the monographic documentation of a remarkable fauna.

The visual system of the Australian wolf spider Lycosa leuckartii (Araneae: Lycosidae): visual acuity and the functional role of the eyes

Abstract Ocular arrangement and visual acuity were examined in Lycosa leuckartii Thorell 1870 (Araneae: Lycosidae), using histological techniques. Major structural and functional features of the visual system, including external and internal ocular organizations, resolution, sensitivity, focal lengths and the field of view, were characterized for each eye. Lycosa leuckartii had a large developmental investment in a specialized visual system with high visual acuity. The field of view extended 360° and displayed the potential for good depth perception. Anterior eyes showed average focal lengths (AL eyes 230.88 µm, AM eyes 276.84 µm), while the posterior eyes far exceeded them (PL eyes 499.26 µm, PM eyes 675.35 µm). Resolution of the anterior eyes was comparable to records in the literature for other lycosids (inter-receptor angle AL eyes 2.45°, AM eyes 1.85°), while the resolution of the posterior eyes was higher (PL eyes 0.78°, PM eyes 0.67°). Sensitivity of the lens (f-numbers) was highest in the secondary eyes and was close to some of the highest reported for Araneae (f-numbers PM eyes 0.58), but when receptor diameters were included in estimates, S-numbers were similar or lower than closely related species (PL eyes 17.5 µm2, PM eyes 17.6 µm2). There is a clear distinction in organization and function between the posterior and anterior eyes of L. leuckartii. The posterior eyes suit long- range predator and prey detection, while the anterior eyes are best for distance judgment and prey capture.