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Coccolithophorids in Polar Waters: Trigonaspis spp. Revisited

100%
Thomsen H. A.
Acta Protozoologica
|
2015
|
vol. 54
|
issue 2
PL
A group of weakly calcified coccolithophorid genera and species were described from polar regions several decades ago. In the interim period a few additional findings 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 flagellar 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.
2
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Coccolithophorids in Polar Waters: Mercedesia gen. nov., Ericiolus, Quaternariella and Porsildia gen. nov.

63%
Thomsen H. A., Østergaard J. B.
Acta Protozoologica
|
2015
|
vol. 54
|
issue 3
PL
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.
3
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Coccolithophorids in Polar Waters: Calciarcus spp. Revisited

63%
Thomsen H. A., Østergaard J. B.
Acta Protozoologica
|
2014
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vol. 53
|
issue 2
PL
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.
4
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Coccolithophorids in Polar Waters: Pappomonas spp. Revisited

63%
Thomsen H. A., Østergaard J. B.
Acta Protozoologica
|
2014
|
vol. 53
|
issue 3
PL
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 Pappomonas 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 that can serve as a reference for the future. The examination of a substantial number of cells unequivocally supports the elevation to species level of P. borealis stat. nov. (previously referred to as P. flabellifera var. borealis) as a separate taxon which is different from P. flabellifera in a number of critical morphological features. Additional evidence in favour of linking P. virgulosa and Bala­niger balticus in a shared life history in combination with significant differences in coccolith morphology between the Pappomonas type species (P. flabellifera) and P. virgulosa has prompted us to synonymise Balaniger balticus with Pappomonas virgulosa, while informally keeping the names of the phases as Balaniger virgulosa HET (= Pappomonas virgulosa phase) and Balaniger virgulosa HOL (= Balaniger balticus phase). A new species, Pappomonas garrisonii sp. nov. is described to accommodate Antarctic material from the Weddell Sea. While fitting into the Pappomonas generic concept, the species adds new dimensions to the overall appearance of the coccolith armour of the cell and emphasizes the close relationship between species of Pappomonas and Papposphaera.
5
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Coccolithophorids in Polar Waters: Wigwamma spp. Revisited

51%
Thomsen H. A., Østergaard J. B., HELDAL M.
Acta Protozoologica
|
2013
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vol. 52
|
issue 4
PL
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.
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