Dataset Information

Two new Brazilian species of Loxosceles Heinecken & Lowe, 1832 with remarks on amazonica and rufescens groups (Araneae, Sicariidae).

ABSTRACT: The genus Loxosceles Heinecken & Lowe, 1832 has 91 representatives in the New World. Despite medical relevancy, the taxonomy of the genus is poorly understood. South American Loxosceles were divided into four groups of species: laeta, spadicea, gaucho and amazonica; this last one has a single species, Loxosceles amazonica Gertsch, 1967. More recently, the natural occurrence of L. amazonica in the New World has been questioned, due to the strong morphological resemblance and close phylogenetic relationship with Old World species, mainly with Loxosceles rufescens (Dufour, 1820). Herein, L. amazonica is rediagnosed and its morphological variation and natural distribution discussed. Two new species closely related to it from northeastern Brazil are also described, Loxosceles willianilsonisp. n., from the state of Rio Grande do Norte, and Loxosceles muriciensissp. n., from the state of Alagoas. The relationships of these new species with L. amazonica and L. rufescens are discussed.

SUBMITTER: Fukushima CS

PROVIDER: S-EPMC5523387 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Two new Brazilian species of Loxosceles Heinecken & Lowe, 1832 with remarks on amazonica and rufescens groups (Araneae, Sicariidae).

Fukushima Caroline Sayuri CS de Andrade Rute Maria Gonçalves RMG Bertani Rogério R

ZooKeys 20170410 667

The genus Loxosceles Heinecken & Lowe, 1832 has 91 representatives in the New World. Despite medical relevancy, the taxonomy of the genus is poorly understood. South American Loxosceles were divided into four groups of species: laeta, spadicea, gaucho and amazonica; this last one has a single species, Loxosceles amazonica Gertsch, 1967. More recently, the natural occurrence of L. amazonica in the New World has been questioned, due to the st ...[more]

PMID: 28769636

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Project description: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.

Dataset Information

Two new Brazilian species of Loxosceles Heinecken & Lowe, 1832 with remarks on amazonica and rufescens groups (Araneae, Sicariidae).

Publications

Two new Brazilian species of <i>Loxosceles</i> Heinecken & Lowe, 1832 with remarks on <i>amazonica</i> and <i>rufescens</i> groups (Araneae, Sicariidae).

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