Nannotax3 - ntax_cenozoic - H. walbersdorfensis group Nannotax3 - ntax_cenozoic - H. walbersdorfensis group

H. walbersdorfensis group


Classification: ntax_cenozoic -> Zygodiscales -> Helicosphaeraceae -> Helicosphaera -> H. walbersdorfensis group
Sister taxa: H. carteri group, H. walbersdorfensis group, H. ampliaperta group, H. recta group, H. lophota group, H. sp.

Daughter taxa (time control age-window is: 0-800Ma)
Helicosphaera stalis
Small, lenticular or rhomboid outline. No distinct flange ending. Two normally inclined pores in central-area.
Helicosphaera vedderi
Similar to H. walbersdorfensis with wider bar and less distinct wing.
Helicosphaera walbersdorfensis
Medium sized. Flange ends in broad wing. Central-area with two normally oblique pores separated by narrow conjunct bar.
Helicosphaera waltrans
Similar to H. walbersdorfensis but larger and with larger openings.
Helicosphaera watkinsii
Species of Helicosphaera with oblique, normally oriented, conjunct bar and blanket confined to central area

Taxonomy:

Citation: H. walbersdorfensis group of Young (1998)
taxonomic rank: species group

Distinguishing features:
Parent taxon (Helicosphaera): Coccoliths with helical flange; arranged spirally on the coccosphere
This taxon: Miocene small to medium sized Helicosphaera species with wing ending flush with flange rather than terminating abruptly. Openings usually strongly oblique. Blanket confiend to central area, in xpl flange dark around whole coccolith.

Farinacci & Howe catalog pages:


Size:
Coccoliths are usually smaller than those of the H.carteri group (5-8 µm vs 8-12 µm). H. stalis is smaller (cocoiths 4-6 µm) and H. waltrans & watkinsii larger (8-12 µm).

Search data:
Lith size: 4->12µm;
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): at top of NN11 zone (100% up, 5.6Ma, in Messinian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within NN2 zone (19.00-22.82Ma, base in Aquitanian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

References:

Theodoridis, S. (1984). Calcareous nannofossil biostratigraphy of the Miocene and revision of the helicoliths and discoasters. Utrecht Micropaleontological Bulletin. 32: 1-271. gs O

Young, J. R. (1998). Neogene. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 225-265. gs


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H. walbersdorfensis group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-6-2024

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=639 Go to Archive.is to create a permanent copy of this page - citation notes
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