1,721,081 research outputs found
Palaeoenvironmental analysis of Early Pleistocene brackish marshes in the Rieti and Tiberino intrapenninic basins (Latium and Umbria, Italy) using ostracods
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Occurrence of fossil and Recent Microceratina Swanson, 1980 (Ostracoda, Eucytherurinae) in the Mediterranean
No full textMixtacandona talianae n.sp. (Crustacea, Ostracoda) from the Holocene of Grotta del Lago (Umbria, central Italy)
No full textPalaeoenvironmental analysis of the 250.000-year Quaternary sediment core of Valle di Castiglione (Latium, Italy) using ostracods
No full textFirst report of non-marine ostracods (Crustacea, Ostracoda) from the Dahlak Archipelago (Eritrea), with the description of two new species
Full text linkThe information on Recent non-marine ostracod faunas of the north-eastern part of the Afrotropical region is still limited. Here we report the first record of ostracods from the Dahlak Archipelago, a group of small islands located in the southern part of the Red Sea off the Eritrean coast. Specimens were obtained by hatching in the laboratory of diapausing eggs occurring in dried mud collected in temporary freshwater ponds, following the so-called "Sars' method". A total of five species were found, including two species new to science, of which four belong to the family Cyprididae (Cypris galefensis, Plesiocypridopsis newtoni, Heterocypris sp., and Chrissia martensi n.sp.) and one to the family Ilyocyprididae (Ilyocypris dahlakensis n.sp.). A detailed description of the morphology of valves and soft parts is given, and COX1 sequences were obtained for four species. Cypris galefensis was so far only known for its type locality in Somalia with a population containing both males and females, whereas our samples consisted exclusively of females. Plesiocypridopsis newtoni, a species characterised by a wide geographic distribution and previously known to occur also in the Afrotropical region, shows marked variability in the prehensile palps of males, as evidenced by comparing the specimens from this study with descriptions available in the literature. The genus Heterocypris (with 15 species) and the genera of the two new species described here, Chrissia (with 17 species) and Ilyocypris (with four species), have been previously reported from this biogeographic region as well. The analysed specimens of Chrissia martensi n.sp. were all females, none of which had sperm inside the carapace, indicating the possibility of parthenogenetic reproduction in this species. A peculiar sexual dimorphism in the valve morphology characterises Ilyocypris dahlakensis n.sp., with females having a straight posterior margin, forming a right angle at the ventral anterior edge. Rehydration of dry sediments collected from arid areas where wet periods are short and often unpredictable has proven to be a successful method for describing aquatic invertebrate biodiversity
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
Geochemical and palaeoecological analyses on Mid Pleistocene to Holocene ostracod assemblages from Valle di Castiglione (Italy): palaeoenvironmental and palaeoclimatic assessment.
No full textSediments from Valle di Castiglione in Italy provide a reference
sequence for Middle Pleistocene to Holocene palaeoclimate reconstruction
of the Mediterranean area. Stable isotope and trace element
signals fromostracodvalves, aswell aspalaeoenvironmental analyses
(autoecology, community analysis and mutual ostracod temperature
range), provided results that cannot be correlated with those derived
from pollen and other proxy records. The lack of correlation is
attributed to the peculiar geological, hydrogeological and hydrochemical
setting of the Valle di Castiglione maar lake. The main trigger
for the hydrochemical changes in thewaterbody and, therefore, in the
ostracod isotopic and trace element signatures, is likely the volcanotectonic
activity in the area. This illustrates how ostracod trace
element and isotopic analyses are not the most appropriate tools for
palaeoclimate reconstructions fromlakeswith complex hydrological
features, such as some crater lakes, and demonstrates the need for care
in selecting lacustrine sequences for such studies
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