Regionalization in biogeography allows division of the globe into areas according to different criteria, such as combination of biotic elements, physiognomy and climate. This regionalization constitutes a hierarchical system which comprises many categories of areas, from realms to biogeographic districts

The systematics of Philodromidae is far from complete, especially for the Neotropical genera. Among these, Petrichus Simon, 1886 is a poorly known genus restricted to arid and semi-arid environments of South America. In this work, we performed a total-evidence analysis to assess the phylogenetic relationships of Petrichus and revised the taxonomy. Petrichus is monophyletic and closer to Titanebo and the New World Ebo. Within Petrichus, two clades are obtained: the Eremean Clade, containing five species displaying a Neotropical distribution; and the Patagonian Clade, with the seven species inhabiting southern South America. Our results also support a previous hypothesis on the phylogenetic relationships within Philodromidae. Thanatini is monophyletic and includes Fageia and Berlandiella, although this is not statistically supported, whereas Philodromini emerges as paraphyletic. We propose Philodromini be expanded to contain all genera having eyes on tubercles analysed in this work plus the closely related Halodromus, whereas the circumscription of Thanatini should await future phylogenetic analyses with new evidence. As for taxonomic proposals, we synonymise Bacillocnemis Mello-Leitão, 1938 with Petrichus, Petrichus ornatus Schiapelli & Gerschman, 1942 and P. luteus (Nicolet, 1849) with P. junior (Nicolet, 1849), P. lancearius Simon, 1905 with P. tullgreni Simon, 1902; we transfer P. corticinus Mello-Leitão, 1944 to Misumenoides Pickard-Cambridge, 1900 (Thomisidae); and P. fuliginosus (Nicolet, 1849), P. cinereus Tullgren, 1901, P. sordidus Tullgren, 1901 and P. zonatus Tullgren, 1901 are regarded as nomina dubia. In total, 13 species are recognised for the genus, of which four are new (described by Griotti & Grismado): P. spira, from western Argentina, P. patagoniensis, from south-western Argentina, P. roigjunenti, from Argentina and Chile and P. eremicus, from north-central Chile. ZooBank: http://zoobank.org/References/1220255e-6431-45c2-adfe-ed58d1f89b17

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Baripus is a ground beetle genus endemic to southern South America, currently distributed across grassland and shrub habitats in mountain and lowland regions. The species of this genus are known to have been affected by the Andean orogeny and the climate changes that occurred during this process. In this study, we seek to understand how the orogeny of the Andes may have led to changes in the climatic niches of the species of Baripus over time. We integrated former ecological and historical biogeographic hypotheses, exploring the use of parsimony optimization of phylogenetically structured climate variables and ancestral character state reconstruction methods. We then performed regression analyses of the optimized climatic niche variables within the phylogenetic tree of Baripus. We were able to infer significant climatic niche constraints, and niche changes that provide new insights to the existing knowledge, supporting former ecological and biogeographic hypotheses for this genus. Such trends in climatic niche could be explained by the rain shadow effect caused by the Andean uplift as well as with other climate shifts associated with temperature and precipitation swings that occurred in this region from the Middle Miocene to the Pliocene.

The link between vegetation structure and spider diversity has been well explored in the literature. However, few studies have compared spider diversity and its response to vegetation at two conceptual levels: assemblage (species diversity) and ensemble (guild diversity). Because of this, we studied spider diversity in riparian and adjacent habitats of a river system from the Chacoan subregion in central Argentina and evaluated their linkage with vegetation structure at these two levels. To assess vegetation structure, we measured plant species richness and vegetation cover in the herb and shrub - tree layers. We collected spiders for over 6 months by using vacuum netting, sweep netting and pitfall traps. We collected 3,808 spiders belonging to 119 morphospecies, 24 families and 9 guilds. At spider assemblage level, SIMPROF analysis showed significant differences among studied habitats. At spider ensemble level, nevertheless, we found no significant differences among habitats. Concerning the linkage with vegetation structure, BIOENV test showed that spider diversity at either assemblage or ensemble level was not significantly correlated with the vegetation variables assessed. Our results indicated that spider diversity was not affected by vegetation structure. Hence, even though we found a pattern in spider assemblages among habitats, this could not be attributed to vegetation structure. In this study, we show that analyzing a community at two conceptual levels will be useful for recognizing different responses of spider communities to vegetation structure in diverse habitat types.

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The genus Baripus Dejean is a carabid beetle endemic to southern South America, inhabiting grassland and shrub habitats in mountain and lowland areas. In this work, the phylogeny of the genus is updated and new species restricted to isolated mountains from the Patagonia Biogeographic Province are described. The cladistic analysis showed that the new mountain species comprise a monophyletic clade with five other species. Within this group, the species are arranged in two internal clades. Each clade contains one or two lowland species with a wide distribution range and the remaining species with microendemic distribution on each mountain system. Their distribution pattern suggests that mountain species of Baripus could have originated since (by) the end of the Cenozoic when the mountains uplifted and acted as a refuge for populations of lowland species that remained isolated and later became differentiated from one another. Based on morphological and cytochrome c oxidase subunit I molecular data, Baripus (Cardiophthalmus) palauco, sp. nov., Baripus (Cardiophthalmus) tromen, sp. nov., Baripus (Cardiophthalmus) aucamahuida, sp. nov. and Baripus (Cardiophthalmus) payun, sp. nov. are described and a key to all currently known species of Baripus (Cardiophthalmus) is provided.