Retecapsa


Classification: Mesozoic -> Podorhabdales -> Cretarhabdaceae -> Retecapsa
Sister taxa: Mattiolia, Wisea ⟩⟨ Speetonia ⟩⟨ Cruciellipsis, Flabellites, Grantarhabdus, Helenea ⟩⟨ Cretarhabdus, Retecapsa, Pickelhaube, Miravetesina

Distinguishing features: Cretarhabdids with central area spanned by an axial cross with lateral bars.


Daughter taxa: All these species are medium sized (5-8 µm) unless noted otherwise. (blue => in age window 0-800Ma)
Axial cross only
Retecapsa incompta
Cretarhabdids with axial cross bars that are broad and bright in XPL with median extinction lines. Distinctly bicyclic rim image in XPL.
Axial cross & 1 lateral bar per quadrant
Retecapsa angustiforata
Cretarhabdids with axial cross & 1 lateral bar per quadrant; central area relatively wide (>1/3 the shield width). All bars of similar breadth and brightness and all 8 holes of similar size.
Retecapsa beckii
Small (4-5 µm) cretarhabdids with 1 lateral bar per quadrant
Retecapsa octofenestrata
Cretarhabdids with axial cross & 1 lateral bar per quadrant; central area relatively narrow (<1/3 the shield width). All 8 holes of similar size..
Retecapsa schizobrachiata
Cretarhabdids with axial cross & 1 lateral bar per quadrant located towards the tips of the cross; central area relatively broad. The 8 central area holes are of unequal size. Medium to large (5-11 µm).
Axial cross & >1 lateral bar per quadrant
Retecapsa crenulata
Cretarhabdids with axial cross & two lateral bars in each quadrant (delimiting around 12 perforations).
Retecapsa surirella
Cretarhabdids with axial cross & about three lateral bars in each quadrant (delimiting around 16 perforations).
Retecapsa escaigii
Cretarhabdids with axial cross & numerous narrow lateral bars per quadrant. Distal shield flat or sloping into central area. 
No axial cross
Retecapsa ficula
Cretarhabdids with narrow central area entirely closed by bars
Retecapsa sp.
Specimens not identified to species level

Taxonomy:

Citation: Retecapsa Black, 1971
Rank: Genus
Type species: Retecapsa brightonii Black, 1971 (considered a synonym of R. angustiforata
Synonyms: Heterorhabdus Noël 1970 - type species H. sinuosus Noël 1970 which is considered a synonym of R. crenulata. This appears to be a senior synonym of Retecapsa.
Taxonomic discussion: Closely related to Cretarhabdus, they are separated on the rather subjective criteria of a single cycle of bars being present in Retecapsa vs. a net in Cretarhabdus.
Some authors have included these forms within Cretarhabdus. and this might be preferable given that Heterorhabdus is probably a senior synonym of Retecapsa.

Farinacci & Howe catalog pages: Retecapsa + * , Heterorhabdus *

Distinguishing features: Cretarhabdids with central area spanned by an axial cross with lateral bars.

Search data:
TagsLITHS: placolith, elliptical, CA: cross-axial, ca_disjunct, grill, process, CROSS-POLARS: rim-unicyclic, R-prominent,
MetricsLith size: 4->11µm;
Data source notes: size range of included species
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 Maastrichtian Stage (100% up, 66Ma, in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): at top of Toarcian Stage (95% up, 174.6Ma, in Toarcian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:

Black, M. (1971a). Coccoliths of the Speeton Clay and Sutterby Marl. Proceedings of the Yorkshire Geological Society. 38: 381-424. gs

Bown, P. R. & Cooper, M. K. E. (1998). Jurassic. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 34-85. gs

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs V O

Noël, D. (1970). Coccolithes Crétacés: La Craie Campanienne du Bassin de Paris. Éditions du Centre National de la Recherche Scientifique, Paris. -. gs


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Retecapsa compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 27-11-2020

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=10996 Go to Archive.is to create a permanent copy of this page - citation notes



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