H. carteri group


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

Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Extant and Pliocene species
Small to medium sized. Flange narrow without distinct wing. Central-area with two small in-line pores.

Like H. carteri but coccoliths with closed central area (i.e. no pores) and usually smaller; also blanket is confined to central area leaving a broader rim of exposed flange elements than in H. carteri.

Medium to large size, flange ends in wing, two inline pores in central-area.

Like H. carteri but central-area with inclined pores.

Like H. carteri but with single long slit in central area

Like H. carteri but with large pores separated by prominent conjunct sub-horizontal bar usually with inverse orientation.

Like H. carteri but pores large. (Late Pliocene- Early Pleistocene)

Like H.carteri but older (NP23-24) - also slits in central area and wing less developed. 

two large pores in central area and flange truncated.

Like H. carteri but with large pores

Oligo-Miocene species with disjunct bar
Bar thin straight and inclined

Bar broad straight and strongly inclined, almost fills central area

Bar broad straight and strongly inclined, fills central area

bar sigmoid, nearly horizontal

Like H. carteri but very large, central-area open, spanned by horizontal disjunct bar.

Taxonomy:

Citation: H. carteri group of Young (1998)
Rank: species group

Distinguishing features: Living and Neogene medium to large species (typically 7-11 microns) with flanges that end in distinct wings.

Farinacci & Howe catalog pages:


Morphology remarks: These are medium to large species (typically 7-11 microns) with flanges that end in distinct wings. They are the most common helicoliths in most samples, but vary markedly through the Neogene. Forms with disjunct (optically discontinuous) bars (H. euphratis & H. intermedia) dominate in the Early Miocene but are replaced progressively by forms with closed central areas or conjunct bars. The blankets on these are initially rather chaotic (H. granulata) but forms with well ordered blankets with two in-line pores (H. carteri) become more common through the Late Miocene. In the Pliocene, forms with large and/or oblique pores (H. sellii and H. wallichii) become common.

Evolution & Phylogeny: H. hyalina and H. wallichii have often been regarded as varieties of H. carteri (e.g. Jordan & Young 1990, Jordan & Green 1994, Cros & Fortuño 2002), since they are similar in size and coccospheres bearing more than one morphotype have been illustrated (e.g. Nishida 1979). However cultures observations and molecular genetic data indicates that they are distinct species (Sáez et al. 2003, Geisen et al. 2004).

Size: Predominantly  medim to large species (coccoliths 8-12 µm), the main excpetions being modern H. pavimentum (coccoliths 4-6 µm) and H. hyalina (coccoliths 5-8 µm). At least on modern H. carteri coccosphere size increase predominantly occurs by incresing the number of coccoliths/langth of th coccosphere rather than by incresing the size of the coccoliths or diameter of the coccoosphere. 

Search data:
TagsLITHS: placolith, asymmetric, RIM: wing,
CSPH: ellipsoidal, varimorphic, V-UNITS: distal shield, R-UNITS: blanket, c-str, px-plate, DETAILS: rim-bicyclic, isogyres kinked, isogyres oblique, isogyres separated,
MetricsLith size: 4->12µm; Coccosphere size: 9->25µm;
Sources:
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): near base of Priabonian Stage (11% up, 37.3Ma, in Priabonian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

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. carteri group compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 21-9-2019

Taxon Search:
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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=636 Go to Archive.is to create a permanent copy of this page - citation notes



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