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Oligocene pteropods (Gastropoda: Thecosomata) from the Kishima Formation, Saga Prefecture, southwest Japan
Ando, Yusuke;
Revista mexicana de ciencias geológicas , 2011,
Abstract: five species in two genera of pteropods, limacina conica (koenen, 1892), l. hospes rolle, 1861, l. karasawai new species, limacina sp. and creseis kishimaensis new species, are described from the oligocene kishima formation of saga prefecture, northwestern kyushu, southwest japan. these species constitute the first oligocene pteropod record from japan. the pteropod fauna of the kishima formation is characterized by the predominate occurrence of the genus limacina. the oligocene pteropod fauna from japan is briefly discussed.
Thecosomata e Gymnosomata (Mollusca, Gastropoda) da cadeia Fernando de Noronha, Brasil
Larrazábal, Maria Eduarda de;Oliveira, Valdeni Soares de;
Revista Brasileira de Zoologia , 2003, DOI: 10.1590/S0101-81752003000200028
Abstract: the mollusca pteropoda from fernando de noronha chain northeastern brazil were studied in order to know their taxonomy and distribution. collections were carried out during the i oceanographical expedition of the revizee program (live resources of the economical exclusive zone) from august to september 1995. the studied area is located between 03°04's-04°23's and 32°19'w-36°26'w, comprising 35 stations. sampling was performed through oblique hauls from 50m depth to surface and from 100 m depth to surface, with a bongo net (300 and 500 μm mesh size, net diameter: 60 cm), that was equipped with a flow meter. samples in a total of 99 were preserved, immediately, in buffered 4% formaldehyde. qualitative and quantitative analyses of the samples were performed based on total sample. the samples were analysed on a counting plate "bogorov" type under a stereo microscope. a total of 8,258 organisms were identified belonging to: 8 families, 16 genera and 27 species. limacina inflata (d′orbigny, 1836) and creseis virgula (rang, 1828) were frequent and very frequent in the area outranking among the studied pteropoda. the total density varied from 2.5 to 3,012.05 org.m-3. highest richness was registered at the continental shelf and slope with 1two species. the pteropoda association showed higher differences between day and night collections. limacina inflata caused this difference due to its higher density at night collections and it was independent of the depth, mesh size and temperature. creseis virgula had its occurrence, mainly, during day time.
Thecosomata e Gymnosomata (Mollusca, Gastropoda) da cadeia Fernando de Noronha, Brasil
Larrazábal Maria Eduarda de,Oliveira Valdeni Soares de
Revista Brasileira de Zoologia , 2003,
Abstract: The Mollusca Pteropoda from Fernando de Noronha Chain Northeastern Brazil were studied in order to know their taxonomy and distribution. Collections were carried out during the I Oceanographical Expedition of the REVIZEE Program (Live Resources of the Economical Exclusive Zone) from August to September 1995. The studied area is located between 03°04'S-04°23'S and 32°19'W-36°26'W, comprising 35 stations. Sampling was performed through oblique hauls from 50m depth to surface and from 100 m depth to surface, with a Bongo net (300 and 500 μm mesh size, net diameter: 60 cm), that was equipped with a flow meter. Samples in a total of 99 were preserved, immediately, in buffered 4% formaldehyde. Qualitative and quantitative analyses of the samples were performed based on total sample. The samples were analysed on a counting plate "Bogorov" type under a stereo microscope. A total of 8,258 organisms were identified belonging to: 8 families, 16 genera and 27 species. Limacina inflata (d′Orbigny, 1836) and Creseis virgula (Rang, 1828) were frequent and very frequent in the area outranking among the studied Pteropoda. The total density varied from 2.5 to 3,012.05 org.m-3. Highest richness was registered at the Continental Shelf and Slope with 1two species. The Pteropoda association showed higher differences between day and night collections. Limacina inflata caused this difference due to its higher density at night collections and it was independent of the depth, mesh size and temperature. Creseis virgula had its occurrence, mainly, during day time.
Description of two new species of Rissoella Gray, 1847 (Mollusca, Gastropoda, Heterobranchia) from Venezuela, with a key to the Caribbean species known for the genus  [cached]
Manuel Caballer Gutierrez,Jesus Ortea,Samuel Narciso
ZooKeys , 2011, DOI: 10.3897/zookeys.115.1163
Abstract: Two new species of the genus Rissoella Gray, 1847 are described from Venezuela, one from the National Park Morrocoy, Rissoella morrocoyensis sp. n. and the other from the Wildlife Refuge Isla de Aves, Rissoella venezolanicola sp. n. R. morrocoyensis sp. n. has a deep umbilicus (partly closed), preumbilical cord, black head, hypobranchial gland marked by a pale yellow boomerang-shaped ribbon and it lives on the leaves of the seagrass Thalassia testudinum Banks & K nig, 1805. R. venezolanicola sp. n. has an angled preumbilical cord which extends to the columella delimiting a trapezoid, a hypobranchial gland marked by a yellow quaver-shaped ribbon and protoconch with fuchsia highlights. It lives on the brown alga Dictyota spp. The records of Rissoella in the Caribbean are revised and illustrations, a comparative table and a key to the Caribbean species known for the genus are provided.
Pteropods from the Caribbean Sea: dissolution as an indicator of past ocean acidification  [PDF]
D. Wall-Palmer,M. B. Hart,C. W. Smart,R. S. J. Sparks
Biogeosciences Discussions , 2011, DOI: 10.5194/bgd-8-6901-2011
Abstract: The aragonite shell–bearing thecosome pteropods are an important component of the oceanic plankton. However, with increasing pCO2 and the associated reduction in oceanic pH (ocean acidification), thecosome pteropods are thought to be particularly vulnerable to shell dissolution. The distribution and preservation of pteropods over the last 250,000 years have been investigated in marine sediment cores from the Caribbean Sea close to the island of Montserrat. Using the Limacina Dissolution Index (LDX), fluctuations in pteropod dissolution through the most recent glacial/interglacial cycles is documented. By comparison to the oxygen isotope record (global sea ice volume), we show that pteropod dissolution is closely linked to global changes in pCO2 and pH and is, therefore, a global signal. These data are in agreement with the findings of experiments upon living pteropods, which show that variations in pH can greatly affect aragonitic shells. The results of this study provide information which may be useful in the prediction of future changes to the pteropod assemblage caused by ocean acidification.
Pteropods from the Caribbean Sea: variations in calcification as an indicator of past ocean carbonate saturation
D. Wall-Palmer, M. B. Hart, C. W. Smart, R. S. J. Sparks, A. Le Friant, G. Boudon, C. Deplus,J. C. Komorowski
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: The aragonite shell-bearing thecosome pteropods are an important component of the oceanic plankton. However, with increasing pCO2 and the associated reduction in oceanic pH (ocean acidification), thecosome pteropods are thought to be particularly vulnerable to shell dissolution. The distribution and preservation of pteropods over the last 250 000 years have been investigated in marine sediment cores from the Caribbean Sea close to the island of Montserrat. Using the Limacina Dissolution Index (LDX), fluctuations in pteropod calcification through the most recent glacial/interglacial cycles are documented. By comparison to the oxygen isotope record (global ice volume), we show that pteropod calcification is closely linked to global changes in pCO2 and pH and is, therefore, a global signal. These data are in agreement with the findings of experiments upon living pteropods, which show that variations in pH can greatly affect aragonitic shells. The results of this study provide information which may be useful in the prediction of future changes to the pteropod assemblage caused by ocean acidification.
Reexamination of the Species Assignment of Diacavolinia Pteropods Using DNA Barcoding  [PDF]
Amy E. Maas, Leocadio Blanco-Bercial, Gareth L. Lawson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0053889
Abstract: Thecosome pteropods (Mollusca, Gastropoda) are an ecologically important, diverse, and ubiquitous group of holoplanktonic animals that are the focus of intense research interest due to their external aragonite shell and vulnerability to ocean acidification. Characterizing the response of these animals to low pH and other environmental stressors has been hampered by continued uncertainty in their taxonomic identification. An example of this confusion in species assignment is found in the genus Diacavolinia. All members of this genus were originally indentified as a single species, Cavolinia longirostris, but over the past fifty years the taxonomy has been revisited multiple times; currently the genus comprises 22 different species. This study examines five species of Diacavolinia, including four sampled in the Northeast Atlantic (78 individuals) and one from the Eastern tropical North Pacific (15 individuals). Diacavolina were identified to species based on morphological characteristics according to the current taxonomy, photographed, and then used to determine the sequence of the “DNA barcoding” region of the cytochrome c oxidase subunit I (COI). Specimens from the Atlantic, despite distinct differences in shell morphology, showed polyphyly and a genetic divergence of <3% (K2P distance) whereas the Pacific and Atlantic samples were more distant (~19%). Comparisons of Diacavolinia spp. with other Cavolinia spp. reveal larger distances (~24%). These results indicate that specimens from the Atlantic comprise a single monophyletic species and suggest possible species-level divergence between Atlantic and Pacific populations. The findings support the maintenance of Diacavolinia as a separate genus, yet emphasize the inadequacy of our current taxonomic understanding of pteropods. They highlight the need for accurate species identifications to support estimates of biodiversity, range extent and natural exposure of these planktonic calcifiers to environmental variability; furthermore, the apparent variation of the pteropods shell may have implications for our understanding of the species’ sensitivity to ocean acidification.
From sea to land and beyond – New insights into the evolution of euthyneuran Gastropoda (Mollusca)
Annette Klussmann-Kolb, Angela Dinapoli, Kerstin Kuhn, Bruno Streit, Christian Albrecht
BMC Evolutionary Biology , 2008, DOI: 10.1186/1471-2148-8-57
Abstract: We found several well supported clades within Euthyneura, however, we could not confirm the traditional classification, since Pulmonata are paraphyletic and Opistobranchia are either polyphyletic or paraphyletic with several clades clearly distinguishable. Sacoglossa appear separately from the rest of the Opisthobranchia as sister taxon to basal Pulmonata. Within Pulmonata, Basommatophora are paraphyletic and Hygrophila and Eupulmonata form monophyletic clades. Pyramidelloidea are placed within Euthyneura rendering the Euthyneura paraphyletic.Based on the current phylogeny, it can be proposed for the first time that invasion of freshwater by Pulmonata is a unique evolutionary event and has taken place directly from the marine environment via an aquatic pathway. The origin of colonisation of terrestrial habitats is seeded in marginal zones and has probably occurred via estuaries or semi-terrestrial habitats such as mangroves.Within the phylum Mollusca, Gastropoda represent the largest and most diverse group in terms of species numbers, niche selection and life history strategies. They have been traditionally classified into three main subclasses: Prosobranchia, Opisthobranchia and Pulmonata [1-3]. Within Gastropoda, Opisthobranchia and Pulmonata have been united as Euthyneura and have since Spengel [4] been contrasted to the Streptoneura (= Prosobranchia). The latter, however, are commonly accepted as being paraphyletic [5].Although a plethora of morphological and anatomical data on Gastropoda have accumulated over the last centuries, it was not until the 1980s that the development of cladistic methodology allowed for analysing these data in a phylogenetic framework e. g. [5-9]. Nevertheless, euthyneuran gastropods have often been neglected in these studies.Several new studies based on morphological data have indicated that Euthyneura is a taxon clearly distinct from the remaining Gastropoda, belonging to a larger monophyletic group, the Heterobranchia. The latter al
Redescri??o dos tipos de Veronicellidae (Mollusca, Gastropoda) neotropicais: X. Os tipos de Diplosolenodes occidentalis (Guilding, 1825) no British Museum (Natural History), Londres
Thomé, José Willibaldo;
Revista Brasileira de Zoologia , 1984, DOI: 10.1590/S0101-81751984000200015
Abstract: diplosolenodes occidentalis (guilding, 1825) (mollusca, gastropoda, veronicellidae) is redescribed upon the examination of types in the british museum (natural history). new characters of external and internal morphohgy are described. a leclotype, is selected.
Los moluscos terrestres (Mollusca: Gastropoda) de Costa Rica: clasificación, distribución y conservación
Barrientos Llosa,Zaidett;
Revista de Biología Tropical , 2010,
Abstract: terrestrial mollusks (mollusca: gastropoda) of costa rica: classification, distribution and conservation. terrestrial mollusks are poorly known worldwide. the country has 183 reported species, 30% endemic and 7% are probably extinct. about 400 species are expected to inhabit the country. biology, ecology, distribution, genetics and other areas of research are unknown for more than 95% of the species. the most diverse families are spiraxidae, orthalicidae and subulinidae. however, the family that may have more species is euconulidae. euconulids inhabit the highlands, where less work has been done. the study of species of highlands will also rise the endemism rate. future taxonomic, biological and ecological work should consider their low vagility, tendency to produce new taxa in sympatry, specific microhabitat requirements, hermaphroditism, high evolutionary rate (10% per million years), and divergence between species (2 to 30%). urgent studies to protect the costa rican malacofauna include: distribution, abundance, effect of land use and climate changes on populations. rev. biol. trop. 58 (4): 1165-1175. epub 2010 december 01.
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