Nannotax3 - ntax_cenozoic - H. recta group

Nannotax3 - ntax_cenozoic - H. recta group Nannotax3 - ntax_cenozoic - H. recta group

H. recta group

Classification: ntax_cenozoic -> Zygodiscales -> Helicosphaeraceae -> Helicosphaera -> H. recta 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)
				H. orientalis and variant
				Helicosphaera orientalis Small species. Flange ends abruptly, no wing or spur. Central-area with inversely oriented pores.
				Helicosphaera pacifica Like H. orientalis but central-area granular, without well defined pores.
				H. obliqua and variants
				Helicosphaera obliqua Large sized, ovoid shape. Only weakly birefringent. Wing ends in spur, central-area with two prominent pores with inverse orientation.
				Helicosphaera perch-nielseniae Like H. obliqua but more rectangular
				Helicosphaera lenticulata Like H. obliqua but more elongate
				Helicosphaera elongata Like H. obliqua but more elongate and rectangular
				Helicosphaera theodoridisii Like H. obliqua but shorter
				H. recta and variants
				Helicosphaera recta Large size, sub-rectangular shape. Wing ends in spur, central-area with two large pores separated by narrow conjunct bar.
				Helicosphaera bipuncta Like H. recta but pores very small
				Helicosphaera truncata Like H. recta but pores larger
				Other species
				Helicosphaera inversasera Simlar to H. obliqua but flange continuous, without notch
				Helicosphaera gertae Very large, rounded species, with closed central-area, or two narrow slits.

Taxonomy:

Citation: H. recta group of Young (1998)

taxonomic rank: species group

Distinguishing features:
Parent taxon (Helicosphaera): Coccoliths with helical flange; arranged spirally on the coccosphere
This taxon: Late Oligocene to Mid Miocene species; flange terminates abruptly rather than expanding into a wing; blanket largely confined to central area, so flange is dark is dark in cross-polars; bar conjunct with rim, horizontal or inversely oriented.

Farinacci & Howe catalog pages:

Morphology:

Distinctive group of Late Oligocene to Mid Miocene Helicosphaera species, with flange terminating abruptly rather than expanding into a wing. Blanket largely confined to central area, so flange is dark is dark in cross-polars. Central area openings usually show inverse orientation (i.e. they point toward the flange termination). Bar conjunct with rim.

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 NP19-20 zone (34.44-36.97Ma, base in Priabonian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: this is a higher taxon page so Neptune data is not plotted. For the customisable plot option go to a genus page Parent: Helicosphaera

References:

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

H. recta group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 8-12-2024

Taxon Search:

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Short stable page link: https://mikrotax.org/Nannotax3/index.php?id=638 Go to Archive.is to create a permanent copy of this page - citation notes

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