2,239 research outputs found

    The family Gallieniellidae (araneae, gnaphosoidea) in the americas

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    Azilia leucostigma Mello-Leitao 1941 considered by Mello-Leitao as a metine (Tetragnathidae), is transferred to the gnaphosoid family Gallieniellidae, as the type species of the new genus Galianoella. The obliquely depressed endites, the flattened irregular postenor median eyes, and the conical anterior lateral spinnerets retaining a sclerotized distal ring, among other characters, clearly place the new genus in the family Gallieniellidae. Galianoella leucostigma is the only gallieniellid so far recorded fom the Americas. This species has a specialized ant-preying behavior. Ant-preying may prove to be characteristic for all the family, as it was suspected in the Madagascan Gallieniella; and it may be associated with the modified chelicerae typical of the family.Fil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin

    Association between neotropical burrowing spiders (araneae: nemesiidae) and mites (acari: heterostigmata, scutacaridae)

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    Whilst collecting burrowing spiders of the family Nemesiidae from 16 localities in Argentina, phoretic mites were found on Stenoterommata iguazu, Stenoterommata platense and Stenoterommata uruguai. These mites are described here: Scutacarus (S.) araneophilus n. sp. and Scutacarus (S.) adgregatus n. sp. Assocations between spiders and scutacarids were not previouly known. Aspects of the biology of the spiders and the interactions between mites and spiders are reported and discussed.Durante colectas de arafias cavadoras de la familia Nemesiidae en I 6 localidades de Argentina, se encontraron acaros foreticos sobre Stenoterommata iguazu, S. platense, and S. uruguai. Se describe aqui a estos acaros, como Scutacarus ( S.) araneophilus n. sp. and Scutacarus ( S.) adgregatus n.sp. Ninguna asociaci6n entre arafias y escutacaridos se conocia previamente. Se discute la interacci6n entre Ios acaros y las arafias, tomando en cuenta Ios datos conocidos de la biologia de ambos.Fil: Ebermann, Ernst. Karl Franzens University; AustriaFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; Argentin

    Borges y el gaucho

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    Fil: Goloboff, Mario

    Roberto Arlt: la máquina literaria

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    El presente trabajo examina las relaciones de Roberto Arlt con el mundo de la literatura a fin de desmentir la imagen de un “advenedizo" o “semianalfabeto" que ciertas críticas y también algunas afirmaciones del propio autor han contribuido a crear. Por el contrario, se intenta demostrar que si lo que Arlt se propuso (y en cierto modo logró) fue dinamitar el edificio literario de su época, las armas con las que contó estaban en los libros, en los arsenales literarios que supo frecuentar.Fil: Goloboff, Mario

    A phylogeny of the tinamous (Aves: Palaeognathiformes) based on integumentary characters

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    A cladistic analysis of the tinamous, including the 47 currently recognized species and some distinct subspecies, was conducted based on 80 integumentary characters from adult and natal plumage, ramphoteca (corneum sheath of bill), and podoteca (horny scales of legs). For the adult plumage (50 characters), we studied feather pigmentation patterns from different pterylae (feather tracts). A criterion of overlap of basic pigmentation elements was used to assign costs to the transformation between the states in most of these characters in such a way that transformations between more similar conditions were less costly. The consensus tree was almost fully resolved, and about 50% of its groups were relatively well supported. Because the only outgroup that could be used provided a poor root, two possible rootings of the ingroup subtree were considered; in both cases, only one of the two traditional subfamilies (the steppe tinamous) was recovered, and the other (the forest tinamous) appeared as paraphyletic. The results of the present analysis are compared with those from an osteological data set, using a strict supertree technique. The combined tree has a large number of nodes, indicating a high degree of congruence between the two data sets.Fil: Bertelli, Sara Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Giannini, Norberto Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; Argentin

    El uso sabio de la ausencia en la aventura intelectual de Macedonio Fernández

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    An optimality criterion to determine areas of endemism

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    A formal method was developed to determine areas of endemism. The study region is divided into cells, and the number of species that can be considered as endemic is counted for a given set of cells (= area). Thus, the areas with the maximum number of species considered endemic are preferred. This is the first method for the identification of areas of endemism that implements an optimality criterion directly based on considering the aspects of species distribution that are relevant to endemism. The methodis implemented in two computer programs, NDM and VNDM, available from the authors. © 2002 Society of Systematic Biologists.Fil: Szumik, Claudia Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; ArgentinaFil: Cuezzo, Fabiana del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; ArgentinaFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; ArgentinaFil: Chalup, Adriana Elizabeth. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Superior de Entomología; Argentin

    The Impact of Unstable Taxa in Coelurosaurian Phylogeny and Resampling Support Measures for Parsimony Analyses

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    Paleontological datasets often have large amounts of missing entries that result in multiple mostparsimonious trees. Highly incomplete and conflictive taxa produce a collapsed strict consensus andseveral methods have been developed for identifying these unstable or rogue taxa in optimal treesderived from phylogenetic analyses. In addition to decreasing consensus resolution, incomplete orconflictive taxa can also severely affect the support values of phylogenetic analysis in paleontologicaldatasets. Here, we explore a protocol for the identification of taxa that decrease jackknife supportvalues in parsimony analysis. The taxa identified are excluded from majority rule jackknife trees,revealing nodes that have either low or high support irrespective of the uncertainties in the placement of unstable taxa. A recently published dataset of coelurosaurian relationships based on 164taxa and 853 characters is explored using this protocol; our protocol detects a total of 40 unstabletaxa as the most detrimental for node supports. Major clades that are well supported in the reducedjackknife tree include Coelurosauria, Maniraptoriformes, Compsognathidae, Ornithomimosauria,Alvarezsauroidea, Therizinosauria, Oviraptorosauria. Clades with moderate support instead includeManiraptora, Pennaraptora, Paraves, Dromaeosauridae, Troodontidae, Anchiornithinae, and earlydiverging clades of Avialae.Fil: Pol, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin

    Cladistics

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    Cladistics is a class of methods of biological classification that groups taxa hierarchically into discrete sets and subsets. This article presents the principles and concepts of cladistics and describes the principal analytical methods. The operations by which observations of organisms are coded for analysis are explained, followed by the methods for reconstructing the hierarchical relationships among taxa (usually expressed as branching diagrams termed cladograms). Statistics and principles for determining the degree of fit between data and cladograms are discussed, which permit choices to be made among competing cladograms.The attached document is the author(’s’) final submitted version of the journal article. You are advised to consult the publisher’s version if you wish to cite from it

    On stability measures and effects of data structure in the recognition of areas of endemism

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    Incomplete data sampling, bias, and like properties of distribution datasets that potentially introduce uncertainty in biogeographical analyses and blur biogeographical patterns; therefore, it is important to understand their influence. Despite their relevance, these problems have been largely overlooked in biogeography, where concepts such as ambiguity, stability or support have not even been defined. Here, we propose two stability measures for hypotheses of areas of endemism (AEs) and use them to explore the degree to which different structural qualities of data affect the results of analyses of endemism. Our findings suggest that different types of data incompleteness have different effects on the recovery of the species composition and the geographical or spatial structure of AEs, showing that distinct levels of sampling coverage affect the stability of results in different ways. We show that a small proportion of poorly sampled species may have a stronger impact on AEs stability than many species with medium sampling and that excluding poorly sampled species from the analyses does not guarantee more stable results. These results highlight the importance of planning data collection and indicate that, in order to obtain more stable results, focusing on completing the distribution of strongly undersampled species might be preferable to adding records of any species randomly.Fil: Casagranda, Maria Dolores. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Goloboff, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin
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