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The Neotropical region is the most diverse on the planet, largely owing to its mosaic of tropical rainforests. Multiple tectonic and climatic processes have been hypothesized to contribute to generating this diversity, including Andean orogeny, the closure of the Isthmus of Panama, the GAARlandia land bridge and historical connections among currently isolated forests. Micrathena spiders are diverse and widespread in the region, and thus a complete phylogeny of this genus allows the testing of hypotheses at multiple scales. We estimated a complete, dated phylogeny using morphological data for 117 Micrathena species and molecular data of up to five genes for a subset of 79 species. Employing eventc-based approaches and biogeographic stochastic mapping while considering phylogenetic uncertainty, we estimated ancestral distributions, the timing and direction of dispersal events and diversification rates among areas. The phylogeny is generally robust, with uncertainty in the position of some of the species lacking sequences. Micrathena started diversifying around 25 Ma. Andean cloud forests show the highest in-situ speciation, while the Amazon is the major dispersal source for adjacent areas. The Dry Diagonal generated few species and is a sink of diversity. Species exchange between Central and South America involved approximately 23 dispersal events and started ~20 Ma, which is consistent with a Miocene age for the Isthmus of Panama closure. We inferred four dispersal events from Central America to the Antilles in the last 20 Myr, indicating the spiders did not reach the islands through the GAARlandia land bridge. We identified important species exchange routes among the Amazon, Andean cloud forests and Atlantic forests during the Plio-Pleistocene. Sampling all species of the genus was fundamental to the conclusions above, especially in identifying the Andean forests as the area that generated the majority of species. This highlights the importance of complete taxonomic sampling in biogeographic studies.
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In recent years, several endemic species of Loxosceles, violin spiders, have been described from the North-Central Chile biodiversity hotspot, some of which have ambiguous placement within the species groups of the genus. In a recent expedition to the Atacama region, we collected male specimens representing new records of two recently described species: Loxosceles vicentei Taucare-Ríos, Brescovit & Villablanca, 2022 and Loxosceles vallenar Brescovit, Taucare-Ríos, Magalhaes & Santos, 2017 (Araneae, Sicariidae). Males of the latter are hitherto unknown and are here described for the first time. Examination of the morphology of these species revealed characters such as an embolic keel and digitiform median receptacles, which suggest they do not belong in the laeta species group, but rather in the spadicea species group, which is briefly re-diagnosed. With carapace lengths smaller than 2 mm, the newly discovered males of L. vallenar are the tiniest members of the genus. In addition, males of this species bear strong macrosetae in the clypeus, a sexually dimorphic character not previously reported in Loxosceles.
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Filistatids, the crevice weavers, are an ancient family of cribellate spiders without extant close relatives. As one of the first lineages of araneomorph spiders, they present a complicated mixture of primitive and derived characters that make them a key taxon to elucidate the phylogeny of spiders, as well as the evolution of phenotypic characters in this group. Their moderate diversity (187 species in 19 genera) is distributed mainly in arid and semi-arid subtropical zones of all continents, except Antarctica. The objective of this paper is to generate a comprehensive phylogenetic hypothesis for this family to advance the understanding of its morphological evolution and biogeography, as well as lay the basis for a natural classification scheme. By studying the morphology using optical and electronic microscopy techniques, we produced a matrix of 302 morphological characters coded for a sample of 103 species of filistatids chosen to represent the phylogenetic diversity of the family. In addition, we included sequences of four molecular markers (COI, 16S, H3 and 28S; 3787 aligned positions) of 70 filistatid species. The analysis of the data (morphological, molecular, and combined) consistently indicates the separation of the Filistatidae into two subfamilies, Prithinae and Filistatinae, in addition to supporting several groups of genera: Filistata, Zaitunia and an undescribed genus from Madagascar; Sahastata and Kukulcania; all Prithinae except Filistatinella and Microfilistata; Antilloides and Filistatoides; a large Old World group including Pritha, Tricalamus, Afrofilistata, Labahitha, Yardiella, Wandella and putative new genera; and a South American group formed by Lihuelistata, Pikelinia and Misionella. Pholcoides is transferred to Filistatinae and Microfilistata is transferred to Prithinae, and each represents the sister group to the remaining genera of its own subfamily. Most genera are valid, although Pikelinia is paraphyletic with respect to Misionella, so we consider the two genera as synonyms and propose a few new generic combinations. Considering the new phylogenetic hypothesis, we discuss the evolution of some morphological character systems and the biogeography of the family. The ages of divergence between clades were estimated using a total-evidence tip-dating approach by including fossils of Filistatidae and early spider clades; this approach resulted in younger age estimates than those obtained with traditional node-dating. Filistatidae is an ancient family that started diversifying in the Mesozoic and most genera date to the Cretaceous. Clades displaying transcontinental distributions were most likely affected by continental drift, but at least one clade shows unequivocal signs of transoceanic long-distance dispersal.
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Arañas , Animales , Regiones Antárticas , Fósiles , Madagascar , Filogenia , Arañas/genéticaRESUMEN
The common ancestor of spiders likely used silk to line burrows or make simple webs, with specialized spinning organs and aerial webs originating with the evolution of the megadiverse "true spiders" (Araneomorphae). The base of the araneomorph tree also concentrates the greatest number of changes in respiratory structures, a character system whose evolution is still poorly understood, and that might be related to the evolution of silk glands. Emphasizing a dense sampling of multiple araneomorph lineages where tracheal systems likely originated, we gathered genomic-scale data and reconstructed a phylogeny of true spiders. This robust phylogenomic framework was used to conduct maximum likelihood and Bayesian character evolution analyses for respiratory systems, silk glands, and aerial webs, based on a combination of original and published data. Our results indicate that in true spiders, posterior book lungs were transformed into morphologically similar tracheal systems six times independently, after the evolution of novel silk gland systems and the origin of aerial webs. From these comparative data, we put forth a novel hypothesis that early-diverging web-building spiders were faced with new energetic demands for spinning, which prompted the evolution of similar tracheal systems via convergence; we also propose tests of predictions derived from this hypothesis.[Book lungs; discrete character evolution; respiratory systems; silk; spider web evolution; ultraconserved elements.].
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Arañas , Animales , Teorema de Bayes , Filogenia , Sistema Respiratorio , Seda/genética , Arañas/genéticaRESUMEN
Studies in evolutionary biology and biogeography increasingly rely on the estimation of dated phylogenetic trees using molecular clocks. In turn, the calibration of such clocks is critically dependent on external evidence (i.e. fossils) anchoring the ages of particular nodes to known absolute ages. In recent years, a plethora of new fossil spiders, especially from the Mesozoic, have been described, while the number of studies presenting dated spider phylogenies based on fossil calibrations increased sharply. We critically evaluate 44 of these studies, which collectively employed 67 unique fossils in 180 calibrations. Approximately 54% of these calibrations are problematic, particularly regarding unsupported assignment of fossils to extant clades (44%) and crown (rather than stem) dating (9%). Most of these cases result from an assumed equivalence between taxonomic placement of fossils and their phylogenetic position. To overcome this limitation, we extensively review the literature on fossil spiders, with a special focus on putative synapomorphies and the phylogenetic placement of fossil species with regard to their importance for calibrating higher taxa (families and above) in the spider tree of life. We provide a curated list including 41 key fossils intended to be a basis for future estimations of dated spider phylogenies. In a second step, we use a revised set of 23 calibrations to estimate a new dated spider tree of life based on transcriptomic data. The revised placement of key fossils and the new calibrated tree are used to resolve a long-standing debate in spider evolution - we tested whether there has been a major turnover in the spider fauna between the Mesozoic and Cenozoic. At least 17 (out of 117) extant families have been recorded from the Cretaceous, implying that at least 41 spider lineages in the family level or above crossed the Cretaeous-Paleogene (K-Pg) boundary. The putative phylogenetic affinities of families known only from the Mesozoic suggest that at least seven Cretaceous families appear to have no close living relatives and might represent extinct lineages. There is no unambiguous fossil evidence of the retrolateral tibial apophysis clade (RTA-clade) in the Mesozoic, although molecular clock analyses estimated the major lineages within this clade to be at least â¼100 million years old. Our review of the fossil record supports a major turnover showing that the spider faunas in the Mesozoic and the Cenozoic are very distinct at high taxonomic levels, with the Mesozoic dominated by Palpimanoidea and Synspermiata, while the Cenozoic is dominated by Araneoidea and RTA-clade spiders.
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The Filistatinae genus Sahastata Benoit, 1968 is distributed in arid and semi-arid areas, from westernmost Sahara to India, and includes seven known species. Four of these are only known from one sex, including Sahastata nigra (Simon, 1897), the type species. Here we present the first description of a male of this species collected near the type locality in Muscat, Oman. Additionally, two new species are described: S. wunderlichi sp. nov. (ââ, Morocco) and S. wesolowskae sp. nov. (ââ, Oman). Sahastata infuscata (Kulczynski, 1901) is newly recorded from Kenya and Yemen and S. nigra is newly recorded from the United Arab Emirates. DNA barcodes are given for S. nigra and the two new species. We observed some details of the life cycle of three Sahastata species, including clutch size, time to maturation, and a biased sex ratio for individuals raised from egg sacs, indicating that only 20-25% of specimens reaching adulthood are males. We provide SEM images of spiders of this genus, some observations on the morphology of spinnerets and male palps, and a distribution map of the species included in the genus.
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Arañas , Animales , Masculino , Marruecos , Omán , Arañas/genéticaRESUMEN
It is now generally accepted that we are going through a major mass extinction event that is causing biodiversity loss at alarming rates (Barnosky et al. 2011). We also know that many species remain to be formally described (e.g. Huber 2014), and concerns have been raised as to whether we will be able to document these before they go extinct (Costello et al. 2013). On one hand, the number of recognized species increases exponentially (e.g. Agnarsson et al. 2013; Sangster Luksenburg 2015). On the other, taxonomic descriptions are becoming more complete and detailed, which is necessarily more time-consuming, leading to an overall decline in the number of species described per taxonomist (Sangster Luksenburg 2015). In this scenario, any method or protocol that increases efficiency in taxonomic descriptions is welcome.
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Biodiversidad , Extinción Biológica , AnimalesRESUMEN
Three new species of the genus Misionella are described from Brazil: Misionella carajas sp. n. and Misionella aikewara sp. n. from caves in the states of Pará and Tocantins and Misionella pallida sp. n. from natural and synanthropic dry areas in the states of Piauí, Maranhão, Rio Grande do Norte and Bahia. These species seem to belong to a distinct group within the genus; the males have an elongate palpal tibia and bulb, a pair of characteristic and hirsute macrosetae in the second metatarsus and the females have internal genitalia with only one pair of spermathecae, with relatively short ducts, lacking the auxiliary receptacles. Their phylogenetic placement and geographic distribution are briefly discussed.
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The Brazilian Caatinga is part of the seasonally dry tropical forests, a vegetation type disjunctly distributed throughout the Neotropics. It has been suggested that during Pleistocene glacial periods, these dry forests had a continuous distribution, so that these climatic shifts may have acted as important driving forces of the Caatinga biota diversification. To address how these events affected the distribution of a dry forest species, we chose Sicarius cariri, a spider endemic to the Caatinga, as a model. We studied the phylogeography of one mitochondrial and one nuclear gene and reconstructed the paleodistribution of the species using modelling algorithms. We found two allopatric and deeply divergent clades within S. cariri, suggesting that this species as currently recognized might consist of more than one independently evolving lineage. Sicarius cariri populations are highly structured, with low haplotype sharing among localities, high fixation index and isolation by distance. Models of paleodistribution, Bayesian reconstructions and coalescent simulations suggest that this species experienced a reduction in its population size during glacial periods, rather than the expansion expected by previous hypotheses on the paleodistribution of dry forest taxa. In addition to that, major splits of intraspecific lineages of S. cariri took place in the Pliocene. Taken together, these results indicate S. cariri has a complex diversification history dating back to the Tertiary, suggesting the history of dry forest taxa may be significantly older than previously thought.
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Evolución Molecular , Genética de Población , Modelos Genéticos , Arañas/genética , Algoritmos , Animales , Teorema de Bayes , Brasil , Núcleo Celular/genética , ADN Mitocondrial/genética , Bosques , Haplotipos , Datos de Secuencia Molecular , Tasa de Mutación , Filogenia , Filogeografía , Análisis de Secuencia de ADN , Análisis Espacial , Clima TropicalRESUMEN
In this paper we revise the species of Sicarius (Araneae: Sicariidae) from the Brazilian Caatinga, the largest tropical dry forest nucleus in the world. We redescribe, designate a neotype and provide new records for Sicarius tropicus (Mello- Leitão, 1936), the only species previously known from the region, and describe three new species: S. cariri n. sp., S. diadorim n. sp. and S. ornatus n. sp. We report high intraspecific variation in the genitalic morphology of these species, especially in females. We also provide anecdotal observations on natural history and behavior of these species, including diet, mating behavior and clutch size. We include an identification key for Brazilian Caatinga species of Sicarius.
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Arañas/anatomía & histología , Arañas/clasificación , Animales , Conducta Animal , Brasil , Ecosistema , Femenino , Masculino , Reproducción , Arañas/fisiologíaRESUMEN
Os autores relatam as estratégias de trabalho da equipe multidisciplinar do NUPAD FM-UFMG com as crianças triadas pelo PETN-MG e atendidas no CEAPS. Salienta-se o papel da brinquedoteca como espaço lúdico e de convivência no comportamento das famílias e das criancas frente aos problemas trazidos pelas doenças crônicas.(AU)
The Centre for Social Support and Education, the CEAPS, is a space that belongs to NUPAD / FM / UFMG and aims to continue to organize social activities, care and support for patients, from the PETN-MG, as well as to their families, who must remain a long day in Belo Horizonte, pending consultations and / or special examinations.(AU)
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Humanos , Recién Nacido , Juego e Implementos de Juego , Educación en Salud , Tamizaje Neonatal , Enfermedad Crónica , Integralidad en SaludRESUMEN
Pozonia Schenkel, 1953 is a genus of Neotropical orb-weaving spiders that currently includes four species, three of which are known only from females. In this paper, the male of Pozonia bacillifera (Simon, 1897) is described and illustrated for the first time, based on a specimen from Nova Lima, state of Minas Gerais, Brazil. It differs from the male of P. nigroventris (Bryant, 1936), the only other known male of the genus, in characters of the genitalia, such as the larger embolus and the smaller ventral lobe of the paracymbium, as well as in the shape of the sternum. This represents the first record of P. bacillifera for the region
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Pozonia Schenkel, 1953 is a genus of Neotropical orb-weaving spiders that currently includes four species, three of which are known only from females. In this paper, the male of Pozonia bacillifera (Simon, 1897) is described and illustrated for the first time, based on a specimen from Nova Lima, state of Minas Gerais, Brazil. It differs from the male of P. nigroventris (Bryant, 1936), the only other known male of the genus, in characters of the genitalia, such as the larger embolus and the smaller ventral lobe of the paracymbium, as well as in the shape of the sternum. This represents the first record of P. bacillifera for the region
RESUMEN
Pozonia Schenkel, 1953 is a genus of Neotropical orb-weaving spiders that currently includes four species, three of which are known only from females. In this paper, the male of Pozonia bacillifera (Simon, 1897) is described and illustrated for the first time, based on a specimen from Nova Lima, state of Minas Gerais, Brazil. It differs from the male of P. nigroventris (Bryant, 1936), the only other known male of the genus, in characters of the genitalia, such as the larger embolus and the smaller ventral lobe of the paracymbium, as well as in the shape of the sternum. This represents the first record of P. bacillifera for the region