Revision of the genus <i>Leucocythere</i> Kaufmann, 1892 (Crustacea, Ostracoda, Limnocytheridae) with the description of a new species and two new tribes

The main aim of the present contribution is to provide an unequivocal diagnosis of the genus Leucocyhtere. It appeared, however, that this could only be effected when embodied in a broader taxonomic framework. The subfamily Limnocytherinae is thus divided into four tribes: Limnocytherini, Dinarocytherini, Cytheridellini and Leucocytherini and diagnoses are provided for these taxa. The latter two are new to science while the rank of Dinarocyhterini was changed from subfamily to tribe. Three genera are lodged in the Leucocytherini: Leucocythere Kaufmann, 1892, Potamocythere Schornikov, 1986 and Ovambocythere Martens, 1989. The former, nominate, genus is characterized and its type species, L. mirabilis, is extensively redescribed. A comparative description of a limnocytheridinid with a somewhat similar appearance, Limnocythere (Limnocytherina) sanctipatricii, is offered. A second species of Leucocythere, L. algeriensis nov. sp., is described from a temporary pool in Algeria. L. baltica (Diebel) is retained as a third species in the genus. A large number of fossil records is reassessed. Most of the Asian fossils, previously assigned to Leucocythere, do not belong in this genus and a revision of their status appears urgent. Some remarks on the validity and position of Leucocytherella are also offered. L. mirabilis is a cold-stenothermic species, with a preference for oligotrophic waters and fine graine sediments. Its status in Europe can at present best be described as endangered, due to rapid degradation of suitable habitats. L. algeriensis nov. sp. and Ovambocythere milani Martens are probably both capable of producing dry resistant stages. This is thus far unique in Cytherids, but the exact taxonomic distribution of this feature remains as yet unknown. Some comments on the phylogeny and historical biogeography are presented. Leucocythere appears to be the more advanced group in the Leucocytherini, the other two genera show more plesiomorphic character states. It is here postulated that the three genera evolve by vicariance from a more widely spread ancestor: Leucocythere in Europe, Potamocythere in Asia and Ovambocythere in Africa. L. algeriensis from northern Africa is doubtlessly from Paleartic stock and its speciation from L. mirabilis must have occured fairly recently. A number of morphological peculiarities of L. mirabilis are discussed with special attention for the carapace and for those soft parts that are used for the mating process. In spite of the fact that many of the peculiarities appear maladaptive at first glance, it must be stressed that L. mirabilis thus far maintained itself very well in its environment, until recent anthropogenic pollution caused its extinction in many localities

Changing Paradigms in Groundwater Ecology - from the &#39;Living Fossils&#39; Tradition to the &#39;New Groundwater Ecology&#39;.

Groundwater ecology merged during the second part of the 20th century with modern ecological practice after having adopted the ecosystem concept. The latter was first applied to karstic systems and separately for alluvial non-consolidated aquifers along surface running waters. Today groundwater ecosystems are studied within a multi- and transdisciplinary framework at various spatial and temporal scales by experts dealing with microbiology, the ecology and systematics of meio- and macro-fauna, geochemistry, hydrogeology and mathematical modelling. A further paradigmatic change occured with the recognition that subterranean assemblages of organisms are formed by both hypogean and epigean taxa. The biological diversity in subterranean ecosystems can be much higher than earlier thought and may even exceed surface diversity in some taxa. This largely unrecognized biodiversity in many cases deserves environmental protection. A third phase in the development of groundwater ecology has occured over the last 15 years with the incorporation of socio-economic research topics within groundwater ecology (Gibert et al., 1994a) and in this sense today we have the New Groundwater Ecology

Sieve-type normal pore canals in Jurassic ostracods: A review with description of a new genus

Sieve-type normal pore canals (StPC) occur commonly in living and fossil cytheroid ostracods but their biological function(s) and evolutionary history are poorly known. The new genus Minyocythere and its four species: Minyocythere macroporosa sp. nov., M. angulata sp. nov., M. maculosa, and M. tuberculata from the Middle Jurassic have StPC prominently developed, display a range of normal pore canals, and provide a context for review of the geological record and palaeobiological potential of these structures, and their application as a taxonomic tool compared with classical approaches. The related Cretaceous genus Dolocythere is reviewed and Dolocythere amphistiela sp. nov. described. The significance of StPC for comparative morphology, systematics, palaeobiology and environmental interpretation are discussed. The range of normal pore canals observed, including StPC, is greater than previously described and several types can occur on one animal implying different life functions. The potential of normal pore canals especially StPC for systematic use is established although good preservation is essential. The functional significance of normal pore canals and their setae must be verified with living material before their evolutionary history can be deduced and their application to palaeoenvironmental interpretation and modern environmental monitoring enhanced

Living males of the ‘ancient asexual’ Darwinulidae (Ostracoda: Crustacea)

Three living male darwinulid ostracods of a new species of the genus Vestalenula have been found in Yakushima, Japan. This is the first report of living darwinulid males for over 100 years and their morphology casts doubt on the two previous records from the late 1800s. The presence of male darwinulids also calls into question the hypothesis that the family Darwinulidae is an exclusively ancient asexual group, reproducing without sex for over 200 million years (Myr). Male carapaces are of similar size and shape to A-1 juvenile females of the same species, suggesting that males may have been dismissed as A-1 juveniles in other living and fossil species. The antennae and fifth limbs are sexually dimorphic: the male antennae have six segments compared with five in the female and a series of putative chemical receptors originating at the extra segment boundary, while the male fifth limbs have well-developed grasping hooks, as in males of many ostracod groups. The lack of Zenker's Organ and of complex internal structures within the hemipenis contradicts previous hypotheses of the phylogenetic position of darwinulids

The implementation of taxonomic harmonisation for Candoninae (Ostracoda, Cypridoidea): A heuristic solution for Fabaeformiscandona tricicatricosa (Diebel and Pietrzeniuk)

International audienceThe concept of Taxonomic Harmonisation (TH) incorporates the search for similarities between taxa mentioned in different data sets and/or taxonomic classification systems, in order to propose a more coherent and homogenous taxonomic system necessary for practical usage in basic and applied scientific activities. For the present project we conceived Fabaeformiscandona tricicatricosa as a species defined by a homeostatic cluster of traits with a given temporal persistence, visible in close relationship with other Fabaeformiscandonaspecies, like F. caudata(Kaufmann), F. levanderi (Hirschmann), and F. siliquosa(Brady), as well as with Candona neglecta Sars which displays analogies in valve shape. We show the advantages to study the above-mentioned taxa by a combination of classic observations in optical microscopy with SEM-techniques and with the treatment of data using geometric morphometrics and multivariate statistics. A protocol for the implementation of the TH of F. tricicatricosa is proposed. We offer a differential diagnosis for F. tricicatricosaas compared to F. caudata, F. levanderi, F. siliquosaand C. neglecta. We use for taxonomic diagnostics a combination of aggregate traits like the average of the outline of valves and qualitative traits, like the shape and the position of a ledge on the posterior side of the valves. We propose to add the term “Consensus” to the species defined by the procedure of the taxonomic harmonisation. To differentiate them from other types of species we propose to use the extension sensu lato following the Linnean species notation. Comments on the origin and the (palaeo)ecology and (palaeo)biogeography of F. tricicatricosaare presented