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SUMMARY A new genus of sand-dwelling photosynthetic dinoflagellate, Testudodinium Horiguchi, Tamura, Katsumata et A. Yamaguchi is proposed based on Testudodinium testudo (Herdman) Horiguchi, Tamura, Katsumata, et A. Yamaguchi comb. nov. (Basionym: Amphidinium testudo Herdman) and a new species in this new genus, Testudodinium maedaense Katsumata et Horiguchi sp. nov. is described. Amphidinium corrugatum is also transferred to this genus, making a new combination T. corrugatum (Larsen et Patterson) Horiguchi, Tamura et A. Yamaguchi. These three species are similar to the members of the genus Amphidinium in having an extremely small episome and a dorsoventrally flattened cell body. They are, however, distinguished from the genus Amphidinium seusu stricto by the possession of a distinct longitudinal furrow in the middle of ventral side of the episome. Phylogenetic trees based on small subunit (SSU) rDNA revealed that all three of these Testudodinium species formed a robust clade and, although statistical support is not high, the tree suggests Testudodinium clade is not closely related to Amphidinium seusu stricto clade. The morphological differences together with molecular data support the establishment of a new genus for A. testudo and its related species. [ABSTRACT FROM AUTHOR]

Abstract: The Rupelian (Lower Oligocene) and Chattian (Upper Oligocene) stratotype sections are both defined on the basis of the southern North Sea Basin sedimentary successions. The characterisation of biotic events occurring within the stratotypes (and equivalents) is vital for the recognition of these stages outside the North Sea Basin. Although the restricted marine setting of the North Sea Basin during most of the Paleogene clearly hampers ‘traditional’ calcareous microfossil calibration, organic-walled dinoflagellate cysts (dinocysts) are increasingly successful in the stratigraphic analysis and calibration of the marginal-marine North Sea Basin successions. Here we present a high-resolution Oligocene dinocyst biostratigraphic zonation scheme for the southern North Sea Basin based on previously published and new dinocyst studies from Belgium, northern Germany and The Netherlands. Eight (southern) North Sea Oligocene (NSO) dinocyst zones (biozones) and four subzones are here defined. Their application on a regional and inter-regional scale is discussed. The stratigraphic important Late Oligocene dinocyst taxon Triphragmadinium demaniae gen. and sp. nov. is formally described. [Copyright &y& Elsevier]

The 1-year seasonal distribution of Ceratium hirundinella was studied in a southern Spanishreservoir. This species grew from June 1988 to April 1989 and showed the highest density in winter, coinciding with the lowest water temperature values and with the period of water circulation. These seasonal dynamics do not accord with the typical description of C. hirundinella in temperate systems as a phytoplankton species of stratified and warm waters. We compared the factors that influenced C. hirundinella development in this system with those operating at different latitudes and concluded that the light and temperature conditions would allow C. hirundinella to grow throughout the year in this reservoir. However, the occurrence of this potential growth is probably regulated by ecological factors, such as the presence of hypolimnetic anoxic conditions and the hydraulic regime of thereservoir. [ABSTRACT FROM PUBLISHER]