Helicosphaera HOL


Classification: ntax_cenozoic -> Holococcoliths -> flat-topped -> Helicosphaera HOL
Sister taxa: Calyptrosphaera -flat, Helicosphaera HOL, Poricalyptra, S. mediterranea HOL type, Zygosphaera

Daughter taxa (time control age-window is: 0-800Ma)
Helicosphaera HOL catilliferus type
Liths with flat-top without perforations; pyramidal boss near centre; rim 5-6 crystallites high; central opening on proximal side small or absent;
Helicosphaera HOL confusus type
Liths with 7-10 depressions; pyramidal boss near centre; distinctly thicker than catilliferus
Helicosphaera HOL ponticuliferus type
Liths with two depressions, extending to proximal surface and separated by a bridge surmounted by a boss.
Helicosphaera pavimentum HOL
Liths with open centre spanned by broad central mound from which 4-6 irregular ridges radiate defining pores.

Taxonomy:

Citation: Helicosphaera HOL type Young et al., 2003
Rank: species group
Taxonomic discussion: It is now clear that this distinctive set of holococcoliths are formed by Helicosphaera, there is, however, continuing uncertainty about the exact relationships between the different heterococcolith and holococcolith morphotypes within Helicosphaera. So, Young & Bown (2014) proposed a revised terminology for referring to the holococcolith phases. This is the system followed here, with some changes from Young et al. (2020). It is a modification of those used by Cros et al. 2000 and Young et al. 2003.

Distinguishing features: Monomorphic; liths solid - formed of layers of crystallites in rhomboid array
Coccolith distal surface with central boss and varying number of depressions.

Farinacci & Howe catalog pages:


Morphology: The Helicosphaera holococcoliths have a distinctive, possibly unique, ultrastructure formed of layers of aligned rhombohedral crystallites. In SEM the rhombohedral packing is characteristic and in LM they behave as single crystal-units with moderate birefringence.
Coccospheres are typically spherical and monomorphic.


Biology & life-cycles: There is unambiguous evidence for asociation of the perforate and ponticuliferus types with Helicosphaera heterococcoliths and weaker evidence that the other stages are also associated. Documented combinations include:

See also: H. carteri group ;

Search data:
TagsLITHS: hollow,
MetricsLith size: 2->3.5µm; Coccosphere size: 9->16µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): Extant Data source: Total of range of species in this database
First occurrence (base): at base of Gelasian Stage (0% up, 2.6Ma, in Gelasian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Couapel, M. J. J., Beaufort, L. & Young, J. R. (2009). A new Helicosphaera - Syracolithus combination coccosphere (Haptophyta) from the Western Mediterranean sea. Journal of Phycology. 45(4): 914-916. gs

Cros, L., Kleijne, A., Zeltner, A., Billard, C. & Young, J. R. (2000b). New examples of holococcolith-heterococcolith combination coccospheres and their implications for coccolithophorid biology. In, Young, J. R., Thierstein, H. R. & Winter, A. (eds) Nannoplankton ecology and palaeocology, Proceedings of the INA7 conference, Puerto Rico, February 2002. Marine Micropaleontology. 39(1-4): 1-34. gs

Triantaphyllou, M. et al. (2016). Coccolithophore combination coccospheres from the NE Mediterranean Sea: new evidence and taxonomic revisions. Micropaleontology. 61(6): 457-472. gs

Young, J. R. & Bown, P. R. (2014). Some emendments to calcareous nannoplankton taxonomy. Journal of Nannoplankton Research. 33(1): 39-46. gs V O

Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue. 1: 1-132. gs V O

Young, J. R., Arapov, J., Skejic, S., Bakrac, A., Buzancic, M. & Triantaphyllou, M. (2020). Verification of the life-cycle of Helicosphaera pavimentum, and discussion of the identity of Syracolithus dalmaticus. Journal of Nannoplankton Research. 30(1): 41-47. gs V O


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Helicosphaera HOL compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 18-4-2021

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=662 Go to Archive.is to create a permanent copy of this page - citation notes



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