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Based on scanning electron microscopy observations, a new species of the coccolithophore genus Calciopappus (Syracosphaeraceae, Prymnesiophyceae) is described from the surface waters off Bergen and from the lower photic zone of sub-tropical and tropical waters. Morphological, coccolith rim structure and biometric analyses strongly support separation of this morphotype from the two described Calciopappus species, but inclusion of it within the genus. The new form differs from the other species in being noticeably smaller and in morpho-structural details of each of the three coccolith types that form the coccosphere: (1) the body coccoliths have an open central area; (2) the whorl coccoliths have a wide central opening and two thumb-like protrusions; and (3) the appendage coccoliths are curved. On this basis, the species is formally described as Calciopappus curvus sp. nov., its systematic affinity is discussed and compared with other extant coccolithophores. [ABSTRACT FROM AUTHOR]

The coccolithophore genus Gephyrocapsa contains a cosmopolitan assemblage of pelagic species, including the bloom-forming Gephyrocapsa oceanica , and is closely related to the emblematic coccolithophore Emiliania huxleyi within the Noëlaerhabdaceae. These two species have been extensively studied and are well represented in culture collections, whereas cultures of other species of this family are lacking. We report on three new strains of Gephyrocapsa isolated into culture from samples from the Chilean coastal upwelling zone using a novel flow cytometric single-cell sorting technique. The strains were characterized by morphological analysis using scanning electron microscopy and phylogenetic analysis of 6 genes (nuclear 18S and 28S rDNA, plastidial 16S and tufA , and mitochondrial cox1 and cox3 genes). Morphometric features of the coccoliths indicate that these isolates are distinct from G. oceanica and best correspond to G. muellerae . Surprisingly, both plastidial and mitochondrial gene phylogenies placed these strains within the E. huxleyi clade and well separated from G. oceanica isolates, making Emiliania appear polyphyletic. The only nuclear sequence difference, 1 bp in the 28S rDNA region, also grouped E. huxleyi with the new Gephyrocapsa isolates and apart from G. oceanica . Specifically, the G. muellerae morphotype strains clustered with the mitochondrial β clade of E. huxleyi , which, like G. muellerae , has been associated with cold (temperate and sub-polar) waters. Among putative evolutionary scenarios that could explain these results we discuss the possibility that E. huxleyi is not a valid taxonomic unit, or, alternatively the possibility of past hybridization and introgression between each E. huxleyi clade and older Gephyrocapsa clades. In either case, the results support the transfer of Emiliania to Gephyrocapsa . These results have important implications for relating morphological species concepts to ecological and evolutionary units of diversity. [ABSTRACT FROM AUTHOR]

Abstract: The evolution of the coccolith genus Lotharingius was investigated in 18samples from the West Rodiles section (Asturias, Northern Spain), Upper Pliensbachian-Lower Toarcian in age. In each sample, the length and width of the coccolith and of its central area were measured on 150specimens of Lotharingius. A total of 2700specimens were measured, and 10,800measurements were obtained. Based on the results of the morphometric analysis, the stratigraphic ranges, the abundance patterns and the light microscope observations, the aims of this work are to determine whether the specimens analysed correspond to different species, to distinct ecophenotypes or to an anagenetic lineage of morphotypes of a single species with overlapping stratigraphic ranges, and to test the influence of the paleoenvironmental perturbations during the Early Toarcian on the studied genus. Three species of Lotharingius were distinguished: L. hauffii, L. sigillatus and L. crucicentralis. Based on central area size and structure, two morphotypes (A and B) of L. hauffii were differentiated. All the parameters measured show a great overlap between the morphotypes and species. An increase in both coccolith and central area size and a development of more complex central area structures were observed through the studied section. L. hauffii is the smallest form, followed by L. sigillatus, and finally L. crucicentralis is the largest species and has the most complex central area structure. A clear decrease in size or “dwarfing” of the species was observed in the samples corresponding to the Early Toarcian environmental perturbations. L. crucicentralis was not identified in these samples. We hypothesize that the changes in size and abundance of the Lotharingius species could be related to the unfavourable palaeoenvironmental conditions for the biomineralization of their coccoliths. [Copyright &y& Elsevier]

Focuses on a study on coccolith volume in deep sea sediments and its use in calibration of carbonate flux estimates. Materials and methods; Discussion; Conclusion.

• Four myr sequence of sapropels in an atoll 1000 s of m above the ocean floor. • Anoxia related to the development of a shallow sill resulting in decreased ventilation. • TOC controlled by cyclic anoxia related to changes in Antarctic ice volume. • IODP Expedition 359 drills sapropel sequence of Late Oligocene-Early Miocene in age. This paper reports on the newly discovered occurrence of thick sequences (∼100 m) of Late Oligocene and Early Miocene (∼24.9 to ∼20 Ma) interbedded organic-rich sediments (sapropels) and pelagic (organic poor) carbonates at Sites U1466 and U1468 drilled in the Maldives archipelago during the International Ocean Discovery Program (IODP) Expedition 359. This occurrence is unusual in that this sequence is located > 1000 m above the surrounding ocean floor within an inter-atoll basin and not linked to any known global oceanic events. Total organic content reaches as high as 35% in the darker layers, while the interbedded carbonates have concentrations of less than 0.1%. Trace elements characteristic of anoxic waters, such as Mo, V, Cr, U, and Pb, correlate positively with concentrations of organic carbon. Nitrogen isotopic data show no evidence that the intervals of high total organic carbon are related to enhanced productivity driven by upwelling. Instead, high organic carbon is associated with intervals of anoxia. We propose that sea-level fluctuations linked to changes in Antarctic ice volume restricted exchange with the open ocean causing bottom waters of the inter-atoll basin to become anoxic periodically. The architecture of the platform at the end of the Oligocene, combined with the global sea-level highstand, set the stage for orbitally-driven sea-level changes producing cyclic deposition of sapropels. The proposed mechanism may serve as an analogue for other occurrences of organic carbon-rich sediments within carbonate platform settings. [ABSTRACT FROM AUTHOR]