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Continental arcs are associated with volcanism concentrated into two main belts—the main arc and back arc, often separated by fold and thrust belts. The Loicas Trough, Argentina, is a post-orogenic extensional feature that obliquely cuts the fold and thrust belts. The trough hosts large Pliocene–Holocene volcanic centres, including Domuyo and Tromen, that lie between the main arc and back arc and thus provide a rare window into this setting. We present major and trace element data for the Loicas Trough, which we combine with geochemical modelling using the Magma Chamber Simulator (MCS) to explore the origin and evolution of the volcanism. The lavas display a wide continuous range from alkaline basalts to subalkaline rhyolites. Trace elements reveal variable extents of arc enrichment (2 < Nb/U < 28), which correlate with proximity to the trench and differentiation indices. Our results and MCS models indicate that the Loicas Trough parental magmas formed from compositionally zoned mantle. Best-fit models indicate that the differentiation occurs at middle and upper crustal levels, in sharp contrast to lower crustal hot zones beneath main arcs. Assimilation of partial crustal melts drives compositional evolution and obscures source signatures. Pure or high fraction end-member partial crustal melts are also identified at Domuyo based on their low Ba (~ 250 ppm) and moderate Sc contents (~ 8 ppm). We find evidence of similar lavas in transtensional settings adjacent to continental arcs worldwide, which do not adhere to the main versus back arc volcanism binary. We suggest the term arc-adjacent magmatism, where compositions are mainly controlled by extensive assimilation and reworking in the middle to upper crust. [ABSTRACT FROM AUTHOR]

The Patagonian batholith was formed through continuous subduction in the southwestern Gondwana margin, from the Early–Middle Jurassic to present times. This study presents a petrological analysis of the La Hoya pluton, an intrusive body located in the North Patagonian Andes near Esquel that is part of the Patagonian batholith. The La Hoya pluton consists of porphyritic biotite–amphibole granodiorites that grade into porphyritic biotite monzogranites, and both facies are associated with minor occurrences of gabbroic-to-tonalitic stocks and doleritic dikes. Amphibole dating yielded a new 40Ar–39Ar stepwise age of 161.5 ± 0.5 Ma for this shallow emplaced pluton. Field, petrographic, whole rock, and mineral geochemical data suggest and indicate that the petrogenetic evolution of the La Hoya pluton involved fractional crystallization, mafic and felsic magma interaction, and possibly mixing of multiple magma sources. Early formed brown resorbed amphibole and labradoritic plagioclase antecrysts crystallized in alkaline-to-transitional (alkaline-to-subalkaline) magmas with temperatures of 834–962 °C and pressures of ~ 2 kbar (up to ~ 7 km depth). Green amphiboles, plagioclases of andesine–oligoclase composition, and biotites crystallized in equilibrium with subalkaline magmas at lower temperatures and pressures (750–806 °C and of ~ 1 kbar; ~ 3.5 km depth). Actinolitic amphibole and albitic plagioclase formed during the hydrothermal alteration associated with the overprinting of post-emplacement solid-state deformation. The La Hoya pluton involved early formed alkaline-to-transitional magmas that progressively became more calc-alkaline with ongoing differentiation. [ABSTRACT FROM AUTHOR]

A new genus of Neotropical Satyrinae butterflies, Viloriodes Pyrcz & Espeland gen. n. is described in the Pedaliodes Butler complex comprising 11–13 genera and more than 400 species. Support for the new genus is provided by a phylogenetic analysis based on target enrichment (TE) data including 618 nuclear loci with a total of 248,940 nucleotides, and the mitochondrial gene cytochrome oxidase subunit 1 (COI). Five species, whose DNA sequences were obtained by TE during this study, form a strongly supported clade sister to the large clade comprising Pedaliodes and four other genera. Complementary COI analysis confirms the monophyly of Viloriodes gen. n., with the above five plus eight other species clustering in highly supported clades in both Bayesian Inference and Maximum Likelihood analyses, and a TE + COI concatenated tree. Based on molecular and morphological data, 30 species are assigned to Viloriodes gen. n. The new genus can be recognized by a set of subtle morphological characteristics of colour patterns and male and female genitalia. An analysis of divergence times indicates that Viloriodes gen. n. and Steromapedaliodes Forster separated around 5.9 Mya. Viloriodes gen. n. has a wider geographic distribution than any other genus of the Pedaliodes complex, being found from central Mexico to northern Argentina and to the Guyana Shield, typically occurring at lower elevations than Pedaliodes. [ABSTRACT FROM AUTHOR]

Biodiversity loss due to climate change is one of the most critical current environmental problems. Global warming is causing substantial species-range shifts and local extirpations, especially for species with restricted distribution ranges. Studies of impact of the climate change on species ranges and environmental suitability have become a fundamental tool for evaluating conservation strategies. However, one important limitation of these approaches is that only species with an adequate number of spatially distinct occurrence records can be modelled, generally excluding threatened rare species from the analyses, a situation referred to as the 'rare species modelling paradox'. To overcome this limitation, we analysed the effect of climate change on the richness of threatened endemic plants of Argentina employing a macroecological modelling approach, using three different modelling techniques (generalized linear mixed models – GLMM, generalized additive models – GAM, and boosted regression trees – BRT), four general circulation models, two representative CO2 concentration pathways (RCPs), and two time periods (2050 and 2070). We identified grid cells with the greatest decline in numbers of threatened endemics, determined species composition in these cells and characterized their vulnerability using three indices. A loss of species richness is observed in ca 83% of the cells, and both protected areas and hotspots of threatened species show significant decrease in future species richness. We identified 32 most affected cells under future climatic projections, including a total of 370 threatened endemic species and exhibiting high beta diversity values (high dissimilarity) among most of the cells. Cells with the highest vulnerability were located along the Central Andes of northwestern Argentina, along the Southern Andean Yungas, High Monte and Central Andean Puna ecoregions, and including a total of 118 threatened endemics (15% of those registered for Argentina) with greater representation of Asteraceae, Apocynaceae, Cactaceae and Iridaceae. However, coverage of protected area network is less than 5% for each of these cells. Our results highlight the urgent need for both in situ and ex situ conservation policies and strategies for the vascular flora of Argentina. [ABSTRACT FROM AUTHOR]

Volcanic eruptions often modify the structure and function of ecosystems at large geographical scales. However, the extent to which species diversity patterns respond to these major natural disturbances is still poorly known. We tested the shape of the species richness – elevation relationship (SRER) and its environmental correlates (thermal environment at ground level, vegetation structure and soil attributes) before and 6 months after (in the first summer) the most recent eruption of the Puyehue Cordon Caulle volcanic complex (PCCVC), which caused an extensive ash accumulation in northwestern Patagonia, Argentina.We re‐established 32, 100‐m2 sampling plots of nine pitfall traps, placed every 100 m of altitude from the base to the summit of three mountains differentially affected by ash deposition, and from which we had pre‐eruption data on richness and environmental variables.Coverage‐based rarefaction/extrapolation curves showed a local post‐eruptive decrease in richness on only one mountain. Generalised additive models (GAMs) showed no significant differences between pre‐ and post‐eruptive SRER shapes. Partial least squares structural equation modelling (PLS‐SEM) showed that woody vegetation and the thermal environment accounted for most of the variation in richness before and after the eruption. Soil attributes were only indirectly associated with beetle richness and the association was mediated by woody vegetation. Ash accumulation ameliorated the thermal environment, promoting a local increase in beetle richness.The rapid recovery of the SRER shape and its environmental correlates suggest that the structuring of local diversity patterns at temperate latitudes of the southern hemisphere is resilient to major volcanic eruptions. [ABSTRACT FROM AUTHOR]