ISSN:0017-3134    

DOI:10.1080/00173139908559215

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ultrastructural and molecular phylogenetic data suggest that dinoflagellates diverged as a lineage possibly as early as the Precambrian. However, the fossil record is problematic before the Mesozoic. From the mid Triassic, though, the fossil record of dinoflagellates is a rich source of information on Mesozoic-Cenozoic dinoflagellates, especially the gonyaulacoids and peridinioids. From the sequence of appearance of species and tabulation types and the impression of early morphological experimentation and later stabilization, the early Mesozoic radiation of dinoflagellates appears to be a real evolutionary event: indeed, dinoflagellate morphology as we know it today may originate in that event. This would explain why it is so difficult to interpret earlier fossils as dinoflagellates. However, that the dinoflagellate lineage existed in some form in the pre-Mesozoic is supported by biogeochemical data, early results of which indicate that certain early Paleozoic acanthomorph acritarchs may belong to the lineage.

ISSN:0017-3134    

DOI:10.1080/00173139908559216

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Dinophytes acquired chloroplasts obviously early in evolution and later lost them multiple times. Most families and genera contain both photosynthetic and heterotrophic species. Chloroplasts enveloped by three membranes with thylakoids in stacks of three, containing peridinin as the main pigment, are regarded as the original dinophyte plastids. Pyrenoids are generally present. Stigmata, if present, are usually parts of the chloroplast or are modified original plastids. The form II type RUBISCO found in the dinophytes is unique for eukaryotes, otherwise known only in some anaerobic bacteria. It is disputed whether the original dinophyte chloroplasts are derived from a prokaryotic or an eukaryotic endosymbiosis. Various dinoflagellates contain aberrant chloroplasts.Glenodinium foliaceumandPeridinium balticumhave a single complete endosymbiont, originally a pcnnate diatom.Podolampas bipeshouses several dictyophycean symbiont cells. The “symbionts” ofLepidodiniurn virideandGymnodinium chlorophorumare highly reduced prasinophyte cells. The chloroplasts ofGymnodinium mikimotoihave aberrant pigments (fucoxanthin derivatives, no peridinin) and fine structure. The dinoflagellate hosts do not seem to contain any parts of the former endosymbiont except the chloroplasts. PhotosyntheticDinophysisspecies have cryptophycean-like chloroplasts, whereas symbiotic cyanobacteria are found in other members of the Dinophysiales, e.g.,Ornithocercus.Various dinophytes, e.g.Gymnodinium aeruginosum, use kleptochloroplasts from ingested cryptophytes transiently for photosynthesis. Original or secondarily acquired chloroplasts can only be used for phylogenetic considerations in exceptionally cases: it seems unlikely that the Prorocentrales have evolved from the Dinophysiales because all Prorocentrales possess original dinoflagellate chloroplasts, whereas no member of the Dinophysiales has such chloroplasts.

ISSN:0017-3134    

DOI:10.1080/00173139908559217

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Glochidiniumgen. nov., a ncw genus of Peridiniaceae based onPeridinium penardiformeLindemann, is herewith erected. Its plate formula is: Po+X+4′+6′′+3C+4S+5′′′+2′′′′ Main diagnostic characters of this new genus are the presence of only 3 cingular plates (it lacks the transitionalone), the third cingular contacting the anterior sulcal plate, and an unusual sulcus holding a small triangular posterior sulcal plate. The thecal morphology and structure of two freshwater planktic species of the genus are described on the basis of LM and SEM observations.G. penardiformecomb. nov. is an infrequent species, albeit widely distributed world-wide. It has been recorded under the names ofPeridinium, GlenodiniumandPeridiniopsis.Peculiar features in the tabulation of the furrows and of the surface sculpture show that the species does not fit any of the known genera, for which reason the new genusGlochidiniumis established.G. platygastersp. nov., the second species included in the genus, differs from the former by its elongated body, the regular pentagonal shape of its large first apical plate, an equally large sulcal anterior plate, and well developed sculpture, chiefly on the antapical plates.Glochidinium penardiformeandG. platygasterwere found in some reservoirs from central and northern Argentina.G. penardiformewas also found in several Argentine rivers and ponds.

ISSN:0017-3134    

DOI:10.1080/00173139908559218

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

For more than 80 years there have existed two speciesProrocentrum cordatum(Ostenfeld) Dodge (=Exuviaella cordataOstenfeld, 1901, originally identified in Caspian Sea samples), andProrocentrum minimum(Pavillard) Schiller(=Exuviaella minimaPavillard, 1916, the Gulf of Lion). Morphologically they differ only by the apparent complete absence of an apical spine in P.cordatum.Their environmental preferences are also very similar. P.minimumis found in different water basins and many authors have increasingly reported frequent blooms of this species during the last decades (Smayda 1990, Hallegraeff 1993). Until the end of the 1960-sP. cordatumwas considered endemic and prominent in the Caspian, Black, Azov and Aral Seas.

ISSN:0017-3134    

DOI:10.1080/00173139908559219

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Motile thecal cells derived from the hatching of single cysts identified asSpiniferites membranaceusandS. ramosushave been used to establish cultures. These cultures were examined in order to assess the cyst-theca relationships of these two taxa. The cultures produced two different motileGonyaulaxspecies belonging to Kofoid'sSpiniferagroup. These cultures were then induced to form a new cyst generation under uniform conditions, and examination of large numbers of the resulting cysts has shown that process development is an extremely variable phenomenon although process morphologies display a continuum within a species. Process length (and to a certain degree, process morphology) requires careful interpretation when used to discriminateSpiniferitestaxa, in both modern and ancient environments.

ISSN:0017-3134    

DOI:10.1080/00173139908559220

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Based on morphological observations carried out on the same material, but submitted to different processing,Trithyrodinium fragileDavey 1969 is herein demonstrated to be a junior synonym ofTrithyrodinium evittiiDrugg 1967. From both original descriptions, the only way that the two species can be separated is by the presence or the absence of a thick brown organic layer on the surface of the endocyst. The present study proves that this is an artificial separation caused by different processing techniques. As a result,T. evittiiis emended in order to encompass specimens, wholly or partially exhibiting this brown organic layer and previously attributed toT. fragile.

ISSN:0017-3134    

DOI:10.1080/00173139908559221

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Rich assemblages of phytoplankton and microforaminifera (foraminifera linings) are found in the marine Lower Cretaceous section from the Yatria River (Subarctic Ural). The Lower Cretaceous (Upper Volgian to Lower Hauterivian) dinocyst and microforaminifera biostratigraphy is calibrated against the ammonite zones. The dinocyst stratigraphy differs from Arctic Canada zonation, except for the BerriasianParagonyaulacysta? borealiszone, and shows significant similarity with the zonal subdivision of Boreal regions of Europe.

ISSN:0017-3134    

DOI:10.1080/00173139908559222

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Nonmarine Cretaceous dinoflagellates were recovered in the last decade from a number of basins in northeastern China, which are mostly oil-bearing. These dinoflagellates show close relationship to the water salinity of palaeoenvironments. Two types of dinoflagellate assemblages may be recognized, one from freshwater to slightly brackish and another from slightly brackish to brackish. The former is characterized by the high dominance of ceratioid cysts, particularly species ofNyktericystaandVesperopsiswhereas the composition of the latter is more varied with gonyaulacoid, peridinioid and ceratioid cysts, and varies with the water salinity.

ISSN:0017-3134    

DOI:10.1080/00173139908559223

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

On the basis of the geographic distribution of some 200 planktonic dinoflagellates recorded from the Arctic, species ranges were typified. Both original and literary data were considered and occurrences were mapped. The types are as follows: Arctic-boreal, boreal, Arctic-boreal-tropical, tropical-boreal, Antarctic-tropical-boreal, bipolar and cosmopolitan. Each type is discussed separately. Mostly, they correspond to the range types known for planktonic diatoms. The evidences of the unity of the Arctic-Boreal Biogeographic Zone are presented. No purely Arctic species have been found. Low endemism of the dinoflagellates of the Arctic-Boreal Zone at specific level (ca 2%) is noted for the Arctic Ocean. The Arctic-Boreal Biogeographic Zone can be subdivided into the Subarctic-Boreal-Atlantic, Subarctic-Boreal-Pacific and Euarctic Circumpolar subzones. As a whole, the Arctic dinoflagellate flora represents impoverished flora characteristic of temperate waters, mostly of the North Atlantic. The problems of bipolarity and bioindication of oceanic currents as well as the value of the so-called Ortmann and Dunbar lines are also discussed.

ISSN:0017-3134    

DOI:10.1080/00173139908559224

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor