The terrestrial biota of the Caribbean islands includes many lineages, some whose presence on the islands dates back some 35–40 million years ago, when land bridges are thought to have linked islands to continents, and others that have colonised more recently via dispersal. The New World spiny orb-weavers (Micrathena Sundevall, 1833) are a diverse group of mostly Neotropical spiders. Eight species have been described on the Greater Antilles islands: three widespread and five single island endemics. Here, using three molecular markers (16S rRNA, ITS-2 and COI) we provide a preliminary phylogenetic test of the taxonomy and biogeography of Caribbean Micrathena through the first molecular phylogeny of the genus. Our analyses support monophyly of the genus, but not that of Caribbean Micrathena with at least 3–4 colonisations from South America. We sampled six of the eight nominal Caribbean species (M. banksi, M. cubana, M. similis, M. forcipata, M. horrida, M. militaris), but demark eight divergent genetic lineages that all are single island endemics, and morphologically distinct. Thus a revision of the taxonomy of Caribbean Micrathena is needed. Our results function foremost to guide more thorough taxon sampling of Micrathena that enable more rigorous assessments of its diversity and biogeography in the Caribbean.

Palpigradi are a poorly understood group of delicate arachnids, often found in caves or other subterranean habitats. Concomitantly, they have been neglected from a phylogenetic point of view. Here we present the first molecular phylogeny of palpigrades based on specimens collected in different subterranean habitats, both endogean (soil) and hypogean (caves), from Australia, Africa, Europe, South America and North America. Analyses of two nuclear ribosomal genes and COI under an array of methods and homology schemes found monophyly of Palpigradi, Eukoeneniidae and a division of Eukoeneniidae into four main clades, three of which include samples from multiple continents. This supports either ancient vicariance or long-range dispersal, two alternatives we cannot distinguish with the data at hand. In addition, we show that our results are robust to homology scheme and analytical method, encouraging further use of the markers employed in this study to continue drawing a broader picture of palpigrade relationships.

The family Hexathelidae ranks among the smaller mygalomorph spider families. Most species are endemic to the Australasian region and the family was traditionally considered an example of a Gondwanan lineage. However, recent studies have cast some doubt on the monophyly of the family. Macrothele is the only genus with an out-of-Gondwana distribution. The bulk of the Macrothele diversity is found in South-east Asia, few species are known from central Africa and two species inhabit Europe: Macrothele calpeiana (Walckenaer, 1805) from the Iberian Peninsula and Macrothele cretica Kulczynski, 1903 endemic to Crete. Here we investigate the origins of the European Macrothele species by means of a multi-locus phylogenetic approach and by inferring the time frame of the diversification of the genus using Bayesian relaxed clock methods. We also provide further insights into the phylogenetic status of the family Hexathelidae. Our results indicate that the diversification of Macrothele traces back to the period of the Gondwana break-up and its present-day distribution most likely reflects the subsequent tectonic plate movements. The two European species were not recovered as sister taxa, suggesting that Macrothele colonised the Mediterranean region twice independently. The polyphyly of the family Hexathelidae is further confirmed and the subfamily Atracinae is identified as the conflicting lineage.

The Pilbara bioregion of Western Australia is an area that contains vast mineral deposits and unique ecosystems. To ensure that mineral deposits are mined with minimal impact on the natural environment, impact assessment surveys are required to determine what fauna and flora species are located within proposed development areas, in particular, by determining the distributions of short-range endemic species (SREs). One infraorder of Arachnida, the Mygalomorphae (trapdoor spiders and their kin), are frequently identified as SREs. These identifications are traditionally performed using morphological techniques; however, only males can be reliably identified to species. Furthermore, the majority of species have not been formally described and males comprise only ∼5% of specimens collected. To assess mygalomorph diversity and the distribution of species in the Pilbara, we employed a molecular barcoding approach. Sequence data from the mitochondrial DNA cytochrome c oxidase subunit I (COI) gene were obtained from 1134 specimens, and analysed using Bayesian methods. Only a fraction of the total mygalomorph fauna of the Pilbara has been documented, and using a species boundary cut-off of 9.5% sequence divergence, we report an increase in species richness of 191%. Barcoding provides a rapid, objective method to help quantify mygalomorph species identifications and their distributions, and these data, in turn, provide crucial information that regulatory authorities can use to assess the environmental impacts of large-scale developments.

The Yilgarn and Pilbara regions of Western Australia are considered biodiversity hotspots for subterranean invertebrates. While the relatively well studied (aquatic) stygofauna are typically constrained to geographically isolated habitats (‘subterranean islands’) and have likely originated from multiple independent epigean ancestors, the troglofauna found in cavernicolous calcretes and fractured rock remains largely unstudied. Here we focus on the pseudoscorpion genera Tyrannochthonius Chamberlin, 1929 and Lagynochthonius Beier, 1951, as common components of the troglofauna, to determine whether they also display highly restricted distributional patterns, and have independent origins. Bayesian and maximum likelihood analyses of sequence data from the mtDNA cytochrome c oxidase I (COI) and the small subunit 18S nuclear genes for subterranean and epigean species from both genera reveal divergent mtDNA lineages that are restricted to single aquifers and/or geographic locations. This strong geographic structuring of troglobitic pseudoscorpions is indicative of short-range endemism and supports the ‘subterranean island’ hypothesis. Further, independent sister relationships between subterranean and epigean taxa indicate multiple invasions into subterranean habitats, likely driven by post-Miocene aridification, consistent with that predicted for the stygofauna. The phylogeny also reveals that Tyrannochthonius   Lagynochthonius is monophyletic but that Lagynochthonius is polyphyletic and nested inside Tyrannochthonius. The results of this study point to common processes that have shaped the diversity and uniqueness of both stygofaunal and troglofaunal communities in Western Australia.

Aoraki denticulata, a widespread mite harvestman endemic to the NW South Island of New Zealand, was postulated to constitute an old lineage with deep genetic history. Expanding on previous studies, we explored its genetic diversity and population structure, phylogeography and diversification patterns. We also examined the systematic implications of such a complex scenario through species delimitation analyses under coalescent-based and barcoding gap discovery methodologies. Our results depict the deep evolutionary history of the A. denticulata lineage, which shows high geographic structure and low genetic connectivity among modern populations. Aoraki denticulata is further subdivided into three lineages: a lineage presently inhabiting the northern region of the Southern Alps (and including the subspecies A. d. major), a second lineage in the north-eastern part of the sampled land, and a third one occupying the south-eastern localities. When using species delimitation methods based on coalescence approaches, large numbers of cryptic species were estimated. Based on morphological and biological evidence, we thus argue that these methods may overestimate species in cases in which genetic divergence is unusually large and discuss the systematic implications of our findings.

Spiders in the subfamily Argyrodinae are known for their associations with other spiders. These associations include predation (araneophagy), web usurpation and kleptoparasitism. Although the majority of the 239 described species are solitary, ∼20 species live in groups in the webs of their hosts. We constructed a molecular phylogeny of argyrodine genera and species in order to investigate (1) the evolution of araneophagy and kleptoparasitism, and (2) group-living and its association with particular types of host webs. We investigated the phylogeny of 41 primarily Asian and American species representing six recognised genera of Argyrodinae, using sequences of four genes: mitochondrial cytochrome c oxidase I (COI) and 16S rRNA (16S); and nuclear 28S rRNA (28S) and histone 3 (H3). We used Bayesian methods to reconstruct the ancestral states of three behavioural characters: foraging method, group-living and specialisation on large webs of large hosts. We tested for correlated evolution of group-living behaviour and specialisation on large webs using reversible-jump Markov chain Monte Carlo methods. The molecular phylogenetic analyses support the monophyly of the Argyrodinae. Reconstruction of ancestral states shows the evolutionary pathway of web-invading behaviour in Argyrodinae is from araneophagy to kleptoparasitism, and then to group-living kleptoparasitism. We found the evolution of group-living behaviour is strongly correlated with specialisation on the use of large host webs, which provide a larger food resource than smaller webs.

The generic placement of New World pholcids assigned to the genus Leptopholcus Simon, 1893 has long been questioned and recent molecular data have shown that Caribbean (Hispaniolan) representatives are more closely related to the Old World genus Micropholcus Deeleman-Reinhold & Prinsen, 1987 than to ‘true’ African Leptopholcus (Dimitrov, Astrin and Huber 2013, Cladistics 29: 132–146). Here we provide new molecular (16S, 18S, 28S, COI, H3, WNT1) and morphological data about Caribbean (Cuban, Puerto Rican) and South American (Brazilian) representatives, supporting the sister-group relationship with Micropholcus and suggesting a monophyletic New World clade that in turn consists of a Caribbean and a South American clade. The ten New World species previously assigned to Leptopholcus are thus transferred to Micropholcus for which an emended diagnosis is provided: M. baoruco (Huber, 2006), comb. nov.; M. brazlandia (Huber, Pérez & Baptista, 2005), comb. nov.; M. dalei (Petrunkevitch, 1929), comb. nov.; M. delicatulus (Franganillo, 1930), comb. nov.; M. evaluna (Huber, Pérez & Baptista, 2005), comb. nov.; M. hispaniola (Huber, 2000), comb. nov.; M. jamaica (Huber, 2000), comb. nov.; M. kiskeya (Huber & Wunderlich, 2006), comb. nov.; M. pataxo (Huber, Pérez & Baptista, 2005), comb. nov.; M. toma (Huber, 2006), comb. nov. Four Brazilian species are newly described: M. piaui, sp. nov.; M. piracuruca, sp. nov.; M. crato, sp. nov.; M. ubajara, sp. nov. Natural history data are provided for M. piaui and M. ubajara.