Aim Our aim was to assess the evolutionary history of the spider genus Loxosceles on the Canary Islands. We unravelled its present diversity within the archipelago, and investigated its origin, mode and tempo of colonization to and between the islands using a phylogenetic framework.Location Canary Islands, Madeira, Iberian Peninsula, North Africa, Mediterranean region, Guinea.Methods We conducted extensive sampling across the Canary Islands, and examined the phylogenetic relationships among the Canary Island representatives of the genus Loxosceles and with regard to species from western Africa and the Mediterranean Basin. We used an evolutionary criterion (general mixed Yule coalescent) to delimit the evolutionary lineages, and applied fossil and biogeographical calibration points to estimate dates for major cladogenetic events within the Canary Islands using a Bayesian framework.Results Phylogenetic analyses revealed the existence of a well-supported clade formed exclusively by Canarian Loxosceles specimens, comprising seven allopatrically distributed evolutionary lineages. Major dispersal events between the islands occurred during the late Miocene. Representatives of the cosmopolitan Loxosceles rufescens were also found on the archipelago. Main conclusionsWe have revealed the existence of an overlooked endemic group of medically important spiders. The pattern of diversity of this group fits well with the general dynamic theory of oceanic island biogeography, where maximum diversity is found on islands of intermediate age. The colonization pathway of the group is compatible with a stepping-stone model. Betweenislands dispersal was the major driving force for diversification in the group, but a few within-island speciation events were also inferred, such as on Gran Canaria, where the Roque Nublo volcanic event acted as a vicariant agent, promoting the split between the two Gran Canarian lineages. The recently introduced L. rufescens is cohabiting with the endemic lineages.

BackgroundUnderstanding the evolutionary history of morphologically cryptic species complexes is difficult, and made even more challenging when geographic distributions have been modified by human-mediated dispersal. This situation is common in the Mediterranean Basin where, aside from the environmental heterogeneity of the region, protracted human presence has obscured the biogeographic processes that shaped current diversity. Loxosceles rufescens (Araneae, Sicariidae) is an ideal example: native to the Mediterranean, the species has dispersed worldwide via cohabitation with humans. A previous study revealed considerable molecular diversity, suggesting cryptic species, but relationships among lineages did not correspond to geographic location.ResultsDelimitation analyses on cytochrome c oxidase subunit I identified 11 different evolutionary lineages, presenting two contrasting phylogeographic patterns: (1) lineages with well-structured populations in Morocco and Iberia, and (2) lineages lacking geographic structure across the Mediterranean Basin. Dating analyses placed main diversification events in the Pleistocene, and multiple Pleistocene refugia, identified using ecological niche modeling (ENM), are compatible with allopatric differentiation of lineages. Human-mediated transportation appears to have complicated the current biogeography of this medically important and synanthropic spider.ConclusionsWe integrated ecological niche models with phylogeographic analyses to elucidate the evolutionary history of L. rufescens in the Mediterranean Basin, with emphasis on the origins of mtDNA diversity. We found support for the hypothesis that northern Africa was the center of origin for L. rufescens, and that current genetic diversity originated in allopatry, likely promoted by successive glaciations during the Pleistocene. We corroborated the scenario of multiple refugia within the Mediterranean, principally in northern Africa, combining results from eight atmosphere–ocean general circulation models (AOGCMs) with two different refugium-delimitation methodologies. ENM results were useful for providing general views of putative refugia, with fine-scale details depending on the level of stringency applied for agreement among models.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-014-0195-y) contains supplementary material, which is available to authorized users.

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BackgroundA large scale semi-quantitative biodiversity assessment was conducted in white oak woodlands in areas included in the Spanish Network of National Parks, as part of a project aimed at revealing biogeographic patterns and identify biodiversity drivers. The semi-quantitative COBRA sampling protocol was conducted in sixteen 1-ha plots across six national parks using a nested design. All adult specimens were identified to species level based on morphology. Uncertain delimitations and identifications due to either limited information of diagnostic characters or conflicting taxonomy were further investigated using DNA barcode information.New informationWe identified 376 species belonging to 190 genera in 39 families, from the 8,521 adults found amongst the 20,539 collected specimens. Faunistic results include the discovery of 7 new species to the Iberian Peninsula, 3 new species to Spain and 11 putative new species to science. As largely expected by environmental features, the southern parks showed a higher proportion of Iberian and Mediterranean species than the northern parks, where the Palearctic elements were largely dominant. The analysis of approximately 3,200 DNA barcodes generated in the present study, corroborated and provided finer resolution to the morphologically based delimitation and identification of specimens in some taxonomically challenging families. Specifically, molecular data confirmed putative new species with diagnosable morphology, identified overlooked lineages that may constitute new species, confirmed assignment of specimens of unknown sexes to species and identified cases of misidentifications and phenotypic polymorphisms.

We conducted an integrative taxonomic study of a radiation of Loxosceles spiders endemic to the Canary Islands combining molecular (mtDNA and nDNA) and morphological data. This led to the formal description of six new species: Loxosceles mahan sp. nov. endemic to Fuerteventura, Lanzarote, and adjacent islets; Loxosceles bentejui sp. nov. and Loxosceles tazarte sp. nov. both endemic to Gran Canaria; Loxosceles guayota sp. nov. and Loxosceles tibicena sp. nov. both endemic to Tenerife; and Loxosceles hupalupa sp. nov. endemic to La Gomera and El Hierro. These new species are included in the Loxosceles rufescens group, and are clearly distinguished from L. rufescens by a conspicuous dark V‐mark posteriorly on the pars cephalica, the embolus length, and the shape of seminal receptacles. Given that a crucial step for the development of proper health management is the correct identification of the species involved in bite accidents, we additionally tested the efficacy of DNA barcoding as a fast and reliable tool for identifying the Loxosceles species found in the Canary Islands, including the human‐introduced L. rufescens. © 2015 The Linnean Society of London

The medical importance of Loxosceles spiders has promoted extensive research on different aspects of their venoms. Most of the reported cases of loxoscelism have occurred in the Americas, and thus, much work has focused on North and South American Loxosceles species. Interestingly, loxoscelism cases are rare in the Mediterranean Basin although Loxosceles rufescens, endemic to the Mediterranean, is an abundant spider even in human-altered areas. Thus, it has been suggested that the venom of L. rufescens could be of less medical relevance than that of its congeners. In this study, we challenge this hypothesis by using multiple approaches to study venom variation in selected species and lineages from the Mediterranean Basin and the Canary Islands. We found that SMase D activity, the key bioactive component of Loxosceles venom, is comparable to American species that are confirmed to have medically relevant bites. The venom protein composition using SDS-PAGE presents some differences among regional Loxosceles taxa in banding pattern and intensity, mostly between the Canarian and L. rufescens lineages. Differences between these species also exist in the expression of different paralogs of the SicTox gene family, with the Canarian species being less diverse. In conclusion, our results do not support the challenged hypothesis, and suggest that venom of these species may indeed be as potent as other Loxosceles species. Pending confirmation of loxoscelism with direct evidence of Loxosceles bites with species identification by professionals, Loxosceles in the Mediterranean region should conservatively be considered medically relevant taxa.

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A new species of the spider genus Loxosceles, L. mrazig sp. n., found in Tunisia is described and illustrated. Th e male bulb shows a high degree of morphological similarity to that of L. gaucho from Brazil, but the proportions of the palpal segments and the general colouration of the body reveal signifi cant diff erences between the two species. A distance analysis of the sequences of the mitochondrial gene cox1 reveals that the specimen from Tunisia shows high genetic distance from L. gaucho (more than 20%). Th e American species L. gaucho and L. laeta form a sister group to the Mediterranean representatives (L. rufescens and the Tunisian specimen).