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The re-examination of the lightly calcified Arctic coccolithophore species, Papposphaera sagittifera, has some inherent challenges due to the research history on this taxon. It is thus obvious in retrospect that the species description based on just a single specimen does not adequately account for the true identity of this taxon. Today we are aware of the existence of at least three species of Papposphaera that have basically the same calyx design while being differentiated based on patterns of central area calcification. In order to remedy this we emend here the description of P. sagittifera and provide an epitype for the species. When realizing that species pairs of Papposphaera and Turrisphaera share a life history, the new combination, P. borealis, was established to accommodate P. sagittifera and T. borealis. However, it turns out that 'sagittifera' is in fact the senior epithet by a few months, which means that the correct name for the species is P. sagittifera with T. borealis added as a synonym. While the P. sagittifera HET and HOL morphological variability across Arctic sites clearly leaves the impression of a single, fairly well defined species, the situation is different with respect to the occurrence of P. sagittifera in Antarctic waters. While there are obvious similarities between P. sagittifera HET across the Polar Regions there are also subtle differences, and most importantly it has been found that the Antarctic P. sagittifera shares a life history with a species of Turrisphaera that is markedly different from T. borealis. While awaiting molecular evidence the Antarctic material is tentatively referred to as P. sagittifera cfr. [ABSTRACT FROM AUTHOR]

In an attempt to establish a taxonomy for the polar contingent of lightly calcified coccolithophores, we are currently dealing with species of Papposphaera. Here we describe a new species, Papposphaera heldalii sp. nov., based on material from Svalbard. The species is unique in terms of calyx design, which is an elegant modification of the standard P. sagittifera theme, and also in terms of the absence of central area calcification in body coccoliths. The species thus occupies a further step in a sequence of five Arctic forms ranging from P. sagittifera via P. sarion, P. arctica and P. iugifera to P. heldalii showing a gradual reduction of central area calcification in body coccoliths. P. heldalii is unique also in the sense that the species has not been found during any of the major Arctic TEM nanoplankton surveys conducted during the last decades. [ABSTRACT FROM AUTHOR]

It has been known for some time that the distinctive polar weakly calcified coccolithophores are also present in samples from lower latitudes. While polar species may actually have a geographic range that vastly extends beyond the polar realms, it is often the case that the warm water regions contribute species that can be allocated to genera previously described based on polar material. We are currently in the process of formally dealing with the warm water species diversity affiliated with the family Papposphaeraceae. In this paper we describe a new genus and species Ventimolina stellata based on material from the Andaman Sea (type locality) and the NW Mediterranean. [ABSTRACT FROM AUTHOR]

Coccolithophorid samples from arctic and antartic regions have been examined for an update on species morphology, life history aspects and biogeography for the coccolithophorid genera Ericiolus and Quaternariella and two other genera here described as new. Mercedesia gen. nov. comprises three new species, M. aspiphora sp. nov. from both polar regions, the arctic M. multistellata sp. nov. and the Antarctic M. pusilla sp. nov. The genus is characterized by its monomorphic nannoliths that are shaped like three-armed stars. The new arctic monospecific genus Porsildia gen. nov. is established for the heterococcolith-bearing species P. acerviphora sp. nov. Combination cells, from the arctic region, bearing holococcoliths of Quaternariella obscura and previously undescribed heterococcoliths, with a Papposphaeracean affinity, are described here for the first time. [ABSTRACT FROM AUTHOR]

A group of weakly calcified coccolithophorid genera and species were described from polar regions several decades ago. In the interim period a few additional fi ndings have been reported adding to the morphological and biogeographical databases of some of the species. The holococcolithophorid genus Trigonaspis is revisited here with the purpose of providing, based on additional sampling from both polar regions, an update on species morphology, life history aspects and biogeography. The genus Trigonaspis as currently circumscribed comprises four taxa - two from each polar region. The triangular plates of crystallites that cover the surfaces of both the tower-shaped fl agellar pole coccoliths and the disc-shaped body coccoliths are the keystone features of the genus. Circumstantial evidence exists linking species of Trigonaspis with species of Pappomonas in haploid-diploid life cycles. [ABSTRACT FROM AUTHOR]

The genus Calciarcus is revisited here with the purpose of providing, based on additional sampling from both polar regions, an update on species diversity and morphology that can serve as a reference for future work. The geographic realm of the genus is significantly widened and a case is built based on consistency in appearance in favour of adding Calciarcus spp. to the well-defined community of bipolar weakly calcified coccolithophorid genera. Despite the multitude of specimens available for analysis and the fact that the specimens examined distribute themselves within three clusters based on morphological features of coccolith superstructures, it has not been possible at this stage to define a robust framework for differentiation among species of Calciarcus. Circumstantial evidence exist linking species of Wigwamma with species of Calciarcus in haploid-diploid life cycles. [ABSTRACT FROM AUTHOR]

A contingent of weakly calcified coccolithophorid genera and species were described from polar regions almost 40 years ago. In the interim period a few additional findings have been reported enlarging the realm of some of the species. The genus Wigwamma is revisited here with the purpose of providing, based on additional sampling from both polar regions, an update on species morphology, life history events and biogeography that can serve as a reference for the future. A new genus, Pseudowigwamma gen. nov. is described to accommodate Wigwamma scenozonion, a species which critically deviates from a core group of five Wigwamma species in terms of coccolith morphology and life history events. Wigwamma armatura sp. nov. is described on the basis of material from the Weddell Sea, Antarctica. While fitting nicely into the Wigwamma generic concept, the species adds new dimensions to the overall appearance of the coccolith armour of the cell. [ABSTRACT FROM AUTHOR]