1,721,002 research outputs found
A peculiar new genus and species of pollen beetles of the Anthystrix-complex of genera from South Africa (Coleoptera: Nitidulidae, Meligethinae)
Full text linkA peculiar new species of pollen beetles of the Anthystrix complex of genera, Austroborovecia anthystrixina gen. nov., sp. nov., is described from northern South Africa (Limpopo Province). This new species, although it appears very similar in external aspect to members of the genus Anthystrix Kirejtshuk, 1981 (including half a dozen species, all from South Africa), exhibits a series of peculiar morphological characters representing obvious autapomorphies (e.g., the male antennomeres III to V fl atly depressed, larger and markedly wider than antennomeres II and VI, a large semi-circular tomentose and blackish area on the orange male last abdominal ventrite, more developed teeth on the outer edge of front tibiae, occipital sulci bordering the dorsal surface of the eyes indistinct, virtual absence of distinct hairs along the outer elytral borders, and peculiarly shaped male genitalia). This series of morphological traits is combined instead with the absence of several of the most important and diagnostic characters of all true Anthystrix species (such as the strongly modified and enlarged antennal club in males, the unique "violin-shaped" median lobe of the aedeagus, and the very deep and narrow longitudinal median incision of the proximal part of the tegmen). Despite the evident outer similarity with most species of Anthystrix, due to some other shared external characters (such as the long, dense and thick golden pubescence covering the whole body, the strongly sinuated and modified male hind tibiae, and the male metaventrite with a large and deep pentagonal impression), the new species cannot be placed in this clade, and requires the institution of a new genus, closely related to Anthystrix. The larval hostplant of the new species is thus far unknown, although almost certainly it is included among members of the tribe Tarchonantheae (Asteraceae), as for all other known members of the Anthystrix-complex of genera
Description of the larva of Ochthebius capicola (Coleoptera: Hydraenidae) from marine rockpools of South Africa
No full textLarval instars II and III of Ochthebius (Ochthebius) capicola (Péringuey 1892) from South Africa are described and illustrated
by SEM, including a detailed analysis of their chaetotaxy and porotaxy. Specimens used in this study were collected
with adults of the same species in marine rockpools. The larval morphology of O. capicola is compared to that of other
members of the same genus occurring in this habitat, contributing to the current taxonomic and phylogenetic debate on
the intrageneric taxonomy of Ochthebiinae
Underestimated diversity: Cryptic species and phylogenetic relationships in the subgenus Cobalius (Coleoptera: Hydraenidae) from marine rockpools
Full text linkMarine rockpools are isolated patches of habitat in the supratidal environment (the so-called splash zone), at the transition between sea and land, found along the rocky shores worldwide and characterized by harsh conditions for life. Nonetheless, few specialized invertebrates successfully colonized this peculiar environment. Among them several members of the water beetles Ochthebius Leach, 1815, subgenus Cobalius Rey (1886), which are found almost exclusively in supratidal and upper-most intertidal marine rockpools from the eastern Atlantic Ocean (Cape Verde, Canary Islands and Morocco, Madeira, Azores) throughout the whole Mediterranean basin. The subgenus Cobalius before 2020 was considered to include ten valid species, based on morphological differences. In late 2020, four additional new species were described. However, recent molecular phylogenetic studies have uncovered further cryptic diversity suggesting the presence of multiple undetected species within this group, highlighting that the species boundaries remain unclear and systematics and taxonomy are in need of revision. In this study we provide a molecular phylogeny based on DNA sequence data from mitochondrial and nuclear genes obtained from ten described species belonging to the subgenus Cobalius, and extensive taxon sampling, in order to better understand the phylogenetic relationships within this genus and to infer the biogeographic processes behind its diversification. We also used a molecular clock to define a time window for diversification of distinct clades within the subgenus, and explore aspects of its evolutionary history. Finally, we used three species delimitation methods (PTP, GMYC and ABGD) to clarify taxonomy and validate species boundaries. Our phylogenetic and biogeographic results identified sixteen independent lineages grouped in four main clades and the possible origin of Cobalius was estimated to be in the Early Miocene (~22 Mya) in W Mediterranean area. Moreover, species delimitation methods suggest there are between 16 and 24 putative species, most of them diverged during the Late Miocene, Pliocene and Pleistocene (6.0–0.11 Mya)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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