Sperm lengths of non‐marine cypridoidean ostracods (Crustacea)
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Abstract Length measurements of sperms of 51 species of Cypridoidea ostracods were taken to supplement the paucity of ostracod sperm data in the published literature. The lengths of the posterior regions (carrying the mitochondria) and the thinner anterior regions were also measured when appropriate. Maximum lengths of sperms for individual species varied from 268 μm for Fabaeformiscandona velifera Smith and Janz, 2008 through to 11 787 μm for Australocypris robusta De Deckker, 1974; these lengths represent the shortest so far recorded for the superfamily and the longest ever recorded in ostracods, respectively. There appears to be only a loose relationship between taxonomy and sperm lengths. Species of the subfamily Candoninae generally have the shortest sperms compared with other subfamilies, but one Candoninae species, Candona altoides Petkovski, 1961, has sperms longer than some species of the families Cyprididae, Ilyocyprididae and Notodromadidae. The family Cyprididae showed the most variation, with sperms ranging from 1000 μm through to 11 787 μm in length. No hypothesis satisfactorily explains the origin of giant sperms in ostracods or the longevity of this trait through geological eras, and their existence remains enigmatic.Keywords:
Ostracod
Subfamily
Ostracod
Outcrop
Middle Miocene disruption
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Abstract. In this study, we investigated ostracod assemblages from the Co To Islands in northeastern Vietnam. We identified 77 ostracod species belonging to 46 genera in nine surface sediment samples and recognized three biofacies (I, II, and III) based on Q-mode cluster analysis. The dominant species of biofacies I and II were Aurila hataii, Loxoconcha japonica, and Xestoleberis hanaii, which commonly occur in seaweed beds from southern China to Japan. This is the first report on the ostracod assemblage from the open-sea area in northeastern Vietnam. We clarified that the ostracod assemblages in the Gulf of Tongking, including northern Vietnam, have a strong biogeographical relationship with East Asia seas. A new species, Loxoconcha cotoensis sp. nov., was described herein from the Co To Islands (http://www.zoobank.org/NomenclaturalActs/41d3fb9f-ae17-4215-82c1-0874a8bf1a30, last access: 3 June 2019).
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Assemblage (archaeology)
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Abstract Fifty-two ostracod taxa were identified from two sediment cores collected from the early Badenian Židlochovice stratotype. Ostracod assemblages were analyzed with a focus on taxonomy, paleoecology, distribution of taxa along the sediment cores, quantification of valve/carapace ratios, and species richness by Simpson’s Reciprocal Index. The changes in ostracod assemblages identified in these cores reflect a shallowing of the marine water-depth from circalittoral/epibathyal to shallow infralittoral, and an increase in the sedimentation rate upwards through time. A comparison of all Badenian ostracod assemblages in the Carpathian Foredeep indicates a high proportion of deep-water ostracod species in Židlochovice and its surroundings, suggesting that the deepest part of the Carpathian Foredeep was probably situated in this part of the Czech Republic.
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Paleoecology
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A new freshwater ostracod Batucypretta paradoxa n.gen., n.sp. is described from Batu Caves, West Malaysia. Batucypretta n.gen. has a unique combination of characters hitherto unknown for any genus of the family Cypridopsidae Kaufmann, 1900. Batucypretta paradoxa n.gen., n.sp. is compared with cyprettine and cypridopsine genera and a new subfamily Batucyprettinae is established.
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This genus, assigned to the family Cytherideidae, subfamily Cuneocytherinae, is the first member of the subfamily to be described from North America. It is abundant in samples from the Lower Cretaceous Kiamichi Formation, uppermost Fredericksburg, Tarrant County, Texas.
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Swamp
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This study focuses on the palaeoecology of the Late Devonian ostracods based on more than 4,500 carapaces and valves collected from stratal sections in western Junggar, NW China. According to the ostracod faunas from the Hongguleleng Formation, 3 ecological assemblages are proposed for open oceanic island arc context, that is, Ostracod Assemblage‐1, Ostracod Assemblage‐2, and Ostracod Assemblage‐3. They characterize the foreshore, nearshore, and offshore environments, respectively. The water energy should be the first environmental factor controlling the composition of the ostracod assemblages from the Lower Member of the Hongguleleng Formation, and salinity fluctuations could be also involved.
Ostracod
Paleoecology
Assemblage (archaeology)
Late Devonian extinction
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Paleoecological characteristics of fossil ostracod shells buried in the lake sediment sequences are increasingly studied and used to indicate the past environmental changes.The hydrological state and water chemistry of a lake,particularly the salinity,ionic composition,water temperature and depth,exert important controls not only on the taxonomy,assemblage,abundance and diversity of ostracod species,but also on the size,morphology,ornamentation,structure and thickness of ostracod shells.Changes in paleohydrological and paleolimnolgical conditions of a lake may be reconstructed based on the paleoecological information of the ostracod shells.Specialists in this field have been focusing their attention on (1)the taxonomy and controls of the salinity and ionic composition of a lake on the changes of ostracod species,(2)the life history and ecological procedure of the ostracod species concerned,to accumulate the ecological data of ostracod species(3)identifying field regular collections of ostracod shells and analyzing samples of lake waters,to learn the controls of the salinity and depth on the ecological characteristics of ostracod shells.
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Problem Statement and Purpose. Generalized results obtained in the implementation of the state topic IV‑1–18: «justification of the boundaries of regional and local stratigraphic divisions of the Phanerozoic of Ukraine for geological maps of the new generation» are. Criteria for recognizing the boundaries of stratigraphic divisions of the meшotic regioyarus of southern Ukraine by ostracods are established. Ostracod complexes were used to characterize the boundaries of stratigraphic divisions of the meotic region of southern Ukraine: ─ according to the leading species of ostracod (upper meotis ─ lower Pont); ─ by paleoecological characteristics of ostracod species (upper Sarmatian-lower meotis; lower-upper meotis). Data&Methods. Thus, complexes of meiotic ostracods were studied on the Kerch Peninsula: Yanysh-Takyl Mulda (Zavetne village), in the Crimea (Alminskа depression: Well. No. 302 (northern outskirts of Rivnopollye village), in the Black Sea depression: (Berezneguvate village (Mykolaiv region). When stratifying various deposits of the meotic regioyarus, it is very important to know the maximum possibility of practical use of ostracod complexes. Stratigraphic resolution of deposits of the meotic regioyarus of southern Ukraine by ostracod complexes-regiopidyarus, i.e. ostracods allow us to distinguish the lower meotic and upper meotic regiopidyarus. Thus, meotic ostracods allow us to distinguish two ostracod complexes in the lower meotic region-complex No. 1 (lower) and complex No. 2 (middle), and in the upper meotic region-complex No. 3. Results. The border between the upper Sarmatian and lower Meotic regions (complex No. 1 (lower)) is distinguished by paleoecological characteristics of ostracod species: Lower meotic region-complex (complex No. 1 (lower)): as noted earlier (Kovalenko, 2001), study of the species composition of lower meotic ostracods of complex No. 1 (Kerch Peninsula. The southern wing of the Yanysh-Takyl Mulda (Zavetne village)) gave grounds to assert that at that time there was a basin in the studied area that was very close in its bionomic conditions to the Kherson (upper Sarmat) one. The late Sarmatian ostracod fauna inherited by this early meotic Basin did not undergo significant changes, and the late Sarmatian ostracods Loxoconcha rimopora Suzin continued to exist; Euxinocythere suljakensis Suzin; Xestoleberis (Xestoleberis) maeotica Suzin; X. (X.) advena Schneider; X. (X.) goretski Golovko; X. (X.) irregularis Schneider and others. However, the appearance of meotic ostracodes, such as Loxoconcha obsoleta Ljuljev and Euxinocythere retituberculata Suzin, allows us to date these deposits to early meotis. The boundary between the lower meotic (complex No. 2) and upper meotic (complex No. 3) regions is distinguished by the paleoecological characteristics of ostracod species. For the first time for the Kerch Peninsula, the appearance of brackish ostracods of the Pontic type (Second migration wave) (Caspiocypris candida (Livental); Tyrrhenocythere pontica (Livental in Agalarova et al.), juv; Euxinocythere (Maeotocythere) praebacuana (Livental); Loxocorniculina diaffarovi Schneider, Loxoconcha praemitridata Agalarova, Camptocypria acronasuta (Livental). The boundary between the upper meotic (complex No. 3) and lower Pontic (complex No. 1) regions is recognized by the leading ostracod species (appearance of the Pontic type of ostracod fauna-genera Loxocorniculina Krstic, 1972; Camptocypria Zalanyi, 1959; Bacunella Schneider, 1958; Pontoniella Mandelstam, 1956; Caspiocypris Mandelstam, 1956 and others.
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