53 research outputs found

    Trapdoor spider genus Actinopus.

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    83 pages : illustrations, maps ; 26 cm.The genus Actinopus Perty, 1833, is revised for Argentina, comprising a total of 23 species. The female of A. insignis (Holmberg, 1881) is described for the first time; the species is found in northern Buenos Aires, southern Santa Fe, and Uruguay. The female of A. longipalpis (Koch, 1842), previously known only from the male type from Uruguay, is described for the first time, and the species is newly cited for Argentina (Entre Ríos). Twenty new species are recognized, described and illustrated. Thirteen of the new species are based on males and females (A. reycali, sp. nov., from Jujuy and Salta; A. clavero, sp. nov., from Córdoba; A. szumikae, sp. nov., from Córdoba, southern Buenos Aires, Santa Fe and Corrientes; A. coylei, sp. nov., from Salta and Santiago del Estero, A. argenteus, sp. nov., from Santiago del Estero, Córdoba and Catamarca, A. ramirezi, sp. nov., from Misiones, A. patagonia, sp. nov., from Chubut, La Pampa, Río Negro and southern Buenos Aires, A. gerschiapelliarum, sp. nov., from Córdoba, northern Buenos Aires, southern Santa Fe, northern La Pampa and Canelones in Uruguay, A. pampa, sp. nov., from La Pampa, A. septemtrionalis, sp. nov., from Salta, Tucumán, Catamarca, and Formosa, A. taragui, sp. nov., from Corrientes, Chaco, and Misiones, A. excavatus, sp. nov., from Córdoba, A. casuhati, sp. nov., from southern Buenos Aires). Only one of the new species described is based on females only (A. indiamuerta, sp. nov., from Tucumán); and the remaining six on males (A. puelche, sp. nov., from southern Buenos Aires and Uruguay, A. cordobensis, sp. nov., from San Luis and Córdoba, A. magnus, sp. nov., from Córdoba, A. ariasi, sp. nov., from Formosa, A. palmar, sp. nov., from Entre Ríos, and A. balcarce, sp. nov., from southern Buenos Aires). New morphological characters that can help solve phylogenetic relationships within the genus are described. A dichotomous key for all the species from Argentina is provided, as well as maps of the known geographic distribution for all the species. Three of the species treated here (A. gerschiapelliarum, A. puelche, and A. insignis) are recorded also for Uruguay

    Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds

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    Uncertainties in the phylogeny of birds (Avialae) and their closest relatives have impeded deeper understanding of early theropod flight. To help address this, we produced an updated evolutionary hypothesis through an automated analysis of the Theropod Working Group (TWiG) coelurosaurian phylogenetic data matrix. Our larger, more resolved, and better-evaluated TWiG-based hypothesis supports the grouping of dromaeosaurids + troodontids (Deinonychosauria) as the sister taxon to birds (Paraves) and the recovery of Anchiornithinae as the earliest diverging birds. Although the phylogeny will continue developing, our current results provide a pertinent opportunity to evaluate what we know about early theropod flight. With our results and available data for vaned feathered pennaraptorans, we estimate the potential for powered flight among early birds and their closest relatives. We did this by using an ancestral state reconstruction analysis calculating maximum and minimum estimates of two proxies of powered flight potential—wing loading and specific lift. These results confirm powered flight potential in early birds but its rarity among the ancestors of the closest avialan relatives (select unenlagiine and microraptorine dromaeosaurids). For the first time, we find a broad range of these ancestors neared the wing loading and specific lift thresholds indicative of powered flight potential. This suggests there was greater experimentation with wing-assisted locomotion before theropod flight evolved than previously appreciated. This study adds invaluable support for multiple origins of powered flight potential in theropods (≥3 times), which we now know was from ancestors already nearing associated thresholds, and provides a framework for its further study. Video Abstract: [Figure presented] Pei et al. use an updated phylogeny of early birds and their closest relatives to reconstruct powered flight potential, showing it evolved at least three times. Many ancestors of the closest bird relatives neared thresholds of powered flight potential, suggesting broad experimentation with wing-assisted locomotion before theropod flight evolved.Fil: Pei, Rui. Institute Of Vertebrate Paleontology And Paleoanthropology Chinese Academy Of Sciences; ChinaFil: Pittman, Michael B.. The University Of Hong Kong; Hong KongFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Dececchi, T. Alexander. Mount Marty College; Estados UnidosFil: Habib, Michael B.. Natural History Museum Of Los Angeles County; Estados UnidosFil: Kaye, Thomas G.. Foundation For Scientific Advancement; Estados UnidosFil: Larsson, Hans C. E.. Mcgill University; CanadáFil: Norell, Mark A.. American Museum of Natural History; Estados UnidosFil: Brusatte, Stephen L.. University of Edinburgh; Reino UnidoFil: Xu, Xing. Institute Of Vertebrate Paleontology And Paleoanthropology Chinese Academy Of Sciences; Chin

    HIV-1 and SARS-CoV-2: Patterns in the evolution of two pandemic pathogens

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    Humanity is currently facing the challenge of two devastating pandemics caused by two very different RNA viruses: HIV-1, which has been with us for decades, and SARS-CoV-2, which has swept the world in the course of a single year. The same evolutionary strategies that drive HIV-1 evolution are at play in SARS-CoV-2. Single nucleotide mutations, multi-base insertions and deletions, recombination, and variation in surface glycans all generate the variability that, guided by natural selection, enables both HIV-1’s extraordinary diversity and SARS-CoV-2’s slower pace of mutation accumulation. Even though SARS-CoV-2 diversity is more limited, recently emergent SARS-CoV-2 variants carry Spike mutations that have important phenotypic consequences in terms of both antibody resistance and enhanced infectivity. We review and compare how these mutational patterns manifest in these two distinct viruses to provide the variability that fuels their evolution by natural selection.Fil: Fischer, Will. Los Alamos National Laboratory; Estados Unidos. New Mexico Consortium; MéxicoFil: Giorgi, Elena E.. New Mexico Consortium; México. Los Alamos National Laboratory; Estados UnidosFil: Chakraborty, Srirupa. Center For Nonlinear Studies; Estados Unidos. Los Alamos National Laboratory; Estados UnidosFil: Nguyen, Kien. Los Alamos National Laboratory; Estados UnidosFil: Bhattacharya, Tanmoy. Los Alamos National Laboratory; Estados UnidosFil: Theiler, James. Los Alamos National Laboratory; Estados UnidosFil: Goloboff, Pablo Augusto. American Museum of Natural History; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Yoon, Hyejin. Los Alamos National Laboratory; Estados UnidosFil: Abfalterer, Werner. Los Alamos National Laboratory; Estados UnidosFil: Foley, Brian T.. Los Alamos National Laboratory; Estados UnidosFil: Tegally, Houriiyah. University Of Kwazulu-natal; SudáfricaFil: San, James Emmanuel. University Of Kwazulu-natal; SudáfricaFil: de Oliveira, Tulio. University of KwaZulu-Natal; SudáfricaFil: Gnanakaran, Sandrasegaram. Los Alamos National Laboratory; Estados UnidosFil: Korber, Bette. Los Alamos National Laboratory; Estados Unidos. New Mexico Consortium; Méxic

    Historical Isolation versus Recent Long-Distance Connections between Europe and Africa in Bifid Toadflaxes (Linaria sect. Versicolores)

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    Background: Due to its complex, dynamic and well-known paleogeography, the Mediterranean region provides an ideal framework to study the colonization history of plant lineages. The genus Linaria has its diversity centre in the Mediterranean region, both in Europe and Africa. The last land connection between both continental plates occurred during the Messinian Salinity Crisis, in the late Miocene (5.96 to 5.33 Ma). Methodology/Principal Findings: We analyzed the colonization history of Linaria sect. Versicolores (bifid toadflaxes), which includes c. 22 species distributed across the Mediterranean, including Europe and Africa. Two cpDNA regions (rpl32-trnL UAG and trnK-matK) were sequenced from 66 samples of Linaria. We conducted phylogenetic, dating, biogeographic and phylogeographic analyses to reconstruct colonization patterns in space and time. Four major clades were found: two of them exclusively contain Iberian samples, while the other two include northern African samples together with some European samples. The bifid toadflaxes have been split in African and European clades since the late Miocene, and most lineage and speciation differentiation occurred during the Pliocene and Quaternary. We have strongly inferred four events of post-Messinian colonization following long-distance dispersal from northern Africa to the Iberian Peninsula, Sicily and Greece. Conclusions/Significance: The current distribution of Linaria sect. Versicolores lineages is explained by both ancien

    Chromosome evolution in Cophomantini (Amphibia, Anura, Hylinae)

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    The hylid tribe Cophomantini is a diverse clade of Neotropical treefrogs composed of the genera Aplastodiscus, Boana, Bokermannohyla, Hyloscirtus, and Myersiohyla. The phylogenetic relationships of Cophomantini have been comprehensively reviewed in the literature, providing a suitable framework for the study of chromosome evolution. Employing different banding techniques, we studied the chromosomes of 25 species of Boana and 3 of Hyloscirtus; thus providing, for the first time, data for Hyloscirtus and for 15 species of Boana. Most species showed karyotypes with 2n = 2x = 24 chromosomes; some species of the B. albopunctata group have 2n = 2x = 22, and H. alytolylax has 2n = 2x = 20. Karyotypes are all bi-armed in most species presented, with the exception of H. larinopygion (FN = 46) and H. alytolylax (FN = 38), with karyotypes that have a single pair of small telocentric chromosomes. In most species of Boana, NORs are observed in a single pair of chromosomes, mostly in the small chromosomes, although in some species of the B. albopunctata, B. pulchella, and B. semilineata groups, this marker occurs on the larger pairs 8, 1, and 7, respectively. In Hyloscirtus, NOR position differs in the three studied species: H. alytolylax (4p), H. palmeri (4q), and H. larinopygion (1p). Heterochromatin is a variable marker that could provide valuable evidence, but it would be necesserary to understand the molecular composition of the C-bands that are observed in different species in order to test its putative homology. In H. alytolylax, a centromeric DAPI+ band was observed on one homologue of chromosome pair 2. The band was present in males but absent in females, providing evidence for an XX/XY sex determining system in this species. We review and discuss the importance of the different chromosome markers (NOR position, C-bands, and DAPI/CMA3 patterns) for their impact on the taxonomy and karyotype evolution in Cophomantini

    A reanalysis of mygalomorph spider families (Araneae). American Museum novitates ; no. 3056

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    32 p. : ill. ; 26 cm.Includes bibliographical references (p. 30-32

    Supplementary_Material_Search_bias

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    C code and Windows executables, to calculate bias for wagner trees and branch-swapping starting from random trees

    South American nemesiids.

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    189 p. : ill. ; 26 cm.Includes bibliographical references (p. 186-189)."The 58 species of Nemesiidae occurring in Peru, Chile, Argentina, and Uruguay are described, keyed, illustrated, and diagnosed. Of those 58 species, 39 are new. Acanthogonatus comprises 27 species; Acanthogonatus segne (Simon) is synonymized with A. franki Karsch; A. guttulata (Simon) is synonymized with A. subcalpeianus (Nicolet); Thalerommata venosa Mello-Leitão is synonymized with A. pissii (Simon); A. notatus (Mello-Leitão) is removed from the synonymy of A. patagonicus (Simon); the female previously identified as A. subcalpeianus was misidentified and belongs to a new species, A. confusus; Bolostromus incursus (Chamberlin) is transferred from the Cyrtaucheniidae to Acanthogonatus; 17 new species of Acanthogonatus are described: A. tolhuaca, A. mulchen, A. chilechico, A. quilocura, A. huaquen, A. juncal, A. alegre, A. nahuelbuta, A. hualpen, A. patagallina, A. vilches, A. recinto, A. peniasco, and A. confusus, from Chile, and A. centralis, A. parana, and A. birabeni, from Argentina; the males of A. franki, A. patagonicus, and A. subcalpeianus, and the female of A. notatus are described for first time. Lycinus Thorell (with eight species) is removed from the synonymy of Mygaloides Nicolet, as Mygaloides is an unidentifiable mygalomorph (perhaps a theraphosid); Lycinus epipiptus (Zapfe) is removed from the synonymy of L. gajardoi (Mello-Leitão); five new species of Lycinus, L. quilicura, L. domeyko, L. frayjorge, L. caldera, and L. tofo are described (all from Chile); L. longipes Thorell does not occur in Chile, previous records actually corresponding to specimens of L. caldera and L. epipiptus; the females of L. gajardoi and L. longipes are described for the first time (previously described female of L. gajardoi is actually that of L. epipiptus). Diplothelopsis Tullgren comprises two species, D. bonariensis Mello-Leitão and D. ornata Tullgren; the placement of D. hastata Mello-Leitão in this genus is almost certainly erroneous, and the genus is exclusively Argentinian. A new genus from Chile is described, Chilelopsis, which contains three new species: C. calderoni (the type species), C. serena, and C. puertoviejo. Chilelopsis is hypothesized to be the sister group of Lycinus + Diplothelopsis. A new genus, Flamencopsis, contains only the type species, F. minima (Chile). Chaco Tullgren comprises seven species; six new species are described: C. tucumana, C. sanjuanina, C. tecka, and C. patagonica from Argentina, and C. tigre and C. socos from Chile; the male of C. obscura is described for first time; Hermacha leporina Simon, from Brazil, said by Raven to belong to Chaco, is transferred to Stenoterommata, and Neostothis Vellard (from Brazil) is removed from the synonymy of Chaco; as relimited, Chaco is restricted to Chile and Argentina. Stenoterommata is represented by seven species (other species occur in Brazil); Stenoterommata argentinensis (Schiapelli and Gerschman) and Brachythele argentina Simon are synonymized with S. platense Holmberg; six new species are described: S. iguazu, S. tenuistylum, S. quena, and S. uruguai, from Argentina, S. crassistylum from Argentina and Uruguay, and S. palmar from Argentina and Brazil. Rachias is represented by only one (new) species, R. timbo. Petropolisia Mello-Leitão is removed from the synonymy of Pselligmus and placed in the synonymy of Rachias. The genus Pycnothele is represented by two species; P. modesta (Schiapelli and Gerschman) is removed from the synonymy of the Brazilian P. singularis Mello-Leitão; the females of P. modesta and P. auronitens (Keyserling) are described for first time. Pselligmus conspersus (Walckenaer) is transferred to Rachias. Xenonemesia Goloboff and Spelocteniza Gertsch are transferred to the Microstigmatidae. Neodiplothele Mello-Leitão is transferred to the Sasoninae (Barychelidae). Brachythele keithi Chamberlin is transferred to the genus Linothele (Dipluridae). A cladistic analysis of nemesiid relationships is provided, based on a matrix including all known species of Acanthogonatus, Chaco, and Diplothelopsini, as well as representatives of most nominal Neotropical nemesiid genera, and several non-Neotropical nemesiids and non-nemesiid bipectinates. The 84 terminals in the matrix were scored for 104 characters. The results of the analysis suggest that Nemesiidae as currently delimited is a paraphyletic group but they do not allow a redelimitation at the familial level; the subfamilies Pycnothelinae and Anaminae as delimited by Raven do not appear as monophyletic"--P. 4
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