Reticulofenestra


Classification: Coccolithophores -> Isochrysidales -> Noelaerhabdaceae -> Reticulofenestra
Sister taxa: Emiliania, Gephyrocapsa, Pseudoemiliania, Reticulofenestra, Noelaerhabdus, Bekelithella, Pyrocyclus,

Daughter taxa: (blue => in age window 0-800Ma) Granddaughter taxa
Subcircular to broadly-elliptical reticulofenestrids with a narrow central area (spanned by delicate proximal net, not visible in lm)

Elliptical reticulofenestrids, central area closed by very robust, conspicuous distal ‘plug’ (birefringent).

Elliptical reticulofenestrids with relatively open central area spanned on the proxmal surface by a robust grill (clearly visible in lm as a birefringent plate with variable number of perforations).

Extant Reticulofenestra species - all small

Neogene elliptical reticulofenestrids with an open central area (spanned by delicate proximal net, not visible in lm)

Typically circular reticulofenestrids with relatively narrow circular central area with robust grill (clearly visible in lm).

Paleogene elliptical reticulofenestrids with open central area (spanned by delicate proximal net, not visible in lm)

Specimens which cannot be assigned to established species - AND SPECIES OF UNCERTAIN VALUE

Taxonomy:

Citation: Reticulofenestra Hay, Mohler & Wade, 1966
Rank: Genus
Type species: Reticulojenestra caucasica Hay Mohler & Wade, 1966
Variants:
Synonyms:
Notes & discussion: Coccoliths are assigned to Reticulofenestra on the basis of absence of distinguishing features, consequently the genus is certainly highly paraphyletic and possibly polyphyletic.

Subdivision of the genus is notoriously problematic, numerous species names have been proposed and species concepts vary widely between authors. Some distinctive groups can be recognised but many taxa are separated on arbitrary criteria such as size. In consequence it is good practice for authors to clearly define their adopted species concepts in all publications.

Here we distinguish seven groups of species. The C. floridanus, R. bisecta, R. lockeri and R. reticulata groups are distinctive sets of species which are rather readily distinguished on straightforward criteria - and indeed have been regarded as separate genera by some authors. The remaining species are all elliptical reticulofenestrids with central openings. These morphotypes occur from the Eocene to the present day often at very high abundances. They vary greatly in size, central opening size and grill details (when visible and preserved) and almost certainly numeros different species are included. Subdivision is, however, very problematic. They are much less common in the Late Oligocene and Early Miocene and in consequence different species names are usually used before and after this interval, so we have separated the R. umbilicus and R. pseudoumbilicus groups.

Distinguishing features: No bridge, no slits

Farinacci & Howe catalog pages: Reticulofenestra + + + * , Dictyococcites + + * , Crenalithus + * , Apertapetra * , Cribrocentrum * , Ericsoniella * , Stradnerius * , Tretosestrum *


Morphology remarks: Coccoliths circular to elliptical, central-area open or closed; central area grill delicate, but quite often preserved.

Most likely ancestor: Toweius - at confidence level 3 (out of 5). Data source: e.g. Romein 1979, Perch-Nielsen 1985, Gallagher 1989, Young et al. 1991 .
Likely descendants: Bekelithella; Gephyrocapsa; Noelaerhabdus; Pseudoemiliania;

Search data:
TagsLITHS: placolith, circular, sub-circular, CA: grill, vacant,
CSPH: spherical, monomorphic, V-UNITS: none, R-UNITS: all, c-str, distal shield, prox shield, tube, DETAILS: ca_conjunct, isogyres kinked, isogyres oblique, rim-unicyclic,
MetricsLith size: 1->20┬Ám;
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): in upper part of Thanetian Stage (62% up, 57.2Ma, in Thanetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M. & Barnes, B. (1961). Coccoliths and discoasters from the floor of the South Atlantic Ocean. Journal of the Royal Microscopical Society. 80: 137-147. gs

Black, M. (1967). New names for some coccolith taxa. Proceedings of the Geological Society of London. 1640: 139-145. gs

Hay, W. W., Mohler, H. P. & Wade, M. E. (1966). Calcareous nannofossils from Nal'chik (northwest Caucasus). Eclogae Geologicae Helvetiae. 59: 379-399. gs

Jordan, R. W. & Young, J. R. (1990). Proposed changes to the classification system of living Coccolithophorids. INA Newsletter. 12(1): 15-18. gs

Krhovsky, J. (1979). Calcareous nannoplankotn from the Eocene/Oligocene boundary of some localities of the Pozdrany and Zdanice units (the West Carpathians, Czechoslovakia). In, V. , P. (ed.) Palaeontological Conference 1977, University Karlova Praha. University Karlova Praha, Prague 775-791. gs

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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Reticulofenestra compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 16-9-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1152 Go to Archive.is to create a permanent copy of this page - citation notes



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