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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 generally accepted based on the finding of combination coccospheres in field samples that Turrisphaera arctica and Papposphaera sarion are alternate life-cycle phases of a single species. However, while recently revisiting P. sarion it became evident that the Turrisphaera phase of this species is not identical with T. arctica but rather is an undescribed species of Turrisphaera. The most conspicuous diagnostic feature of T. arctica, an asymmetrical and tilted hypertrophy of the distal tube opening in circum-flagellar coccoliths, was hinted at in the first description of the taxon. However, focus was here on the overall similarity between T. borealis and T. arctica to the extent that the rather conspicuous difference between the two taxa was not clearly recognized by the authors of the taxon, nor by any researcher who has worked on these species since then.We present herematerial of T. arctica from various Arctic locations (WestGreenland,NEGreenland, Svalbard) that completelymatches the type material fromResoluteBay,Cornwallis Island. This material additionally comprised (NE Greenland) large numbers of combination coccospheres that clearly indicate that T. arctica shares a life history with an as yet undescribed species of Papposphaera. This allows us to emend the description of T. arctica including also its heterococcolithophore phase, and in this contextmaking use of the combination P. arctica whichwas established decades ago, yet here with the specific comment that P. sarion is no longer a valid synonym of P. arctica. [ABSTRACT FROM AUTHOR]

Papposphaera sarion was first described from West Greenland waters and has not since then been reported from other sites. We present here additional material of P. sarion from the type locality, transmission electron images of P. sarion from the NEW polynya (NE Greenland) and scanning electron images from Svalbard. Study of a vastly extended source of images provides new morphological data, particularly on the variability of coccolith central area calcification in this species. Combination coccospheres involving a Turrisphaera sp.were frequently observed in samples from the NEW polynya as was also the holococcolithophore Turrisphaera phase of this species. Papposphaera sarion has in its life-cycle previously been associated with Turrisphaera arctica.However, a careful re-examination of the micrographs accompanying the description of T. arctica and unpublishedmaterial available to us clearly reveals that T. arctica combines with a different, but as yet undescribed species of Papposphaera. Astriking similarity is pointed out between P. sarion HET and species of Stradnerlithus, e.g. Stradnerlithus fragilis from the middle Jurassic. [ABSTRACT FROM AUTHOR]

Scale-bearing siliceous nannoplankton are occasionally encountered in surface seawater samples, but are rarely identified or illustrated. In this study, the morphological diversity of the haptophyte Hyalolithus neolepis and the enigmatic Petasaria heterolepis are investigated in scanning and transmission electron microscopes using materials from around theworld. Results show that H. neolepis scales exhibit variation in the width of the marginal hyaline area, but intermediate specimens make separation of the two morphologies difficult. Petasaria heterolepis scales also show differences, in the presence of tubercle rows in the hyaline area and degree of hyaline areal coverage, but separation into discrete varieties is difficult at present. However, specimens with scales bearing a protuberance are considered to be distinct enough to warrant the erection of a new species, Petasaria protuberans Jordan,Malinverno, Šupraha, Thomsen et Young sp. nov. [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]

SUMMARY During a summer cruise to the Ross Sea (Antarctica) areas of snow-covered sea ice were red-coloured due to high concentrations of the recently described Pyramimonas tychotreta Daugbjerg. Light microscopy of living material revealed that the population was comprised of quadriflagellate motile cells and thick-walled cysts. The red colour was due to large numbers of secondary carotenoid-containing granules, positioned in the periphery of motile cells and cysts. Mature cysts also contained numerous starch grains and lipid droplets. Cells from a red-coloured field sample turned green overnight as the secondary carotenoids disappeared when cells were placed in low light conditions. The sample then exhibited the typical grass-green colour of motile cells observed in water samples from the area. Under reduced light motile cells showed strong positive phototaxis. The encystment process involved the asexual transformation of quadriflagellate cells into cysts. A single type of square cyst scale, with perforated floors and walls, replaced the body scales of motile cells. A marked extension, often ending in a hook was at each corner of the cyst scales. Germinating cysts produced four motile cells. Electron microscopy showed the cyst wall to be tri-layered, with a thin, electron-dense inner layer, a thick middle layer and a thin outer layer. Sea ice samples with dense populations of motile cells and cyst stages also contained elongate uniflagellate cells. These cells were covered with box scales, foot-print scales, an underlayer of pentagonal scales, limuloid scales and flagellar hair scales identical to those present on the quadriflagellate stage. We tentatively suggest that the uniflagellate stage represents a gamete and its presence implies the occurrence of sexual reproduction. Although, fusion of gametes was not observed, a biflagellate cell with a larger volume was seen which may have been a zygote. How this stage fits into of the life history remains to be explained. [ABSTRACT FROM AUTHOR]

Provides information on a study which reported the biodiversity of nanoflagellates in central California waters. Materials and methods of the study; Classification of primitive green algae; Discussion on prasinophycean taxa.

Investigates prymnesiophyte life stories involving both flagellate heterococcolithophorid and holococcolithophorid stages. Analysis of four different types of prymnesiophyte flagellates with heterococcoliths from species of the genera Papposphaera and Pappomonas Manton and Oates; Phases of a coccolithophorid life history.