Nannotax3 - ntax_cenozoic - Placorhombus


Classification: ntax_cenozoic -> Coccolith families inc sed -> narrow rimmed placoliths -> Placorhombus
Sister taxa: C. sphaeroidea HET, Navilithus, Placorhombus, Tetralithoides, Turrilithus

Daughter taxa (time control age-window is: 0-800Ma)
Placorhombus ziveriae
striae on all four plates sub-parallel to coccolith width
Placorhombus sp. cf. ziveriae
striae on end plates sub-parallel to coccolith length
Placorhombus sp.
Specimens which cannot be assigned to established species


Citation: Placorhombus Young & Geisen, in Young et al., 2003
Rank: Genus
Type species: Placorhombus ziveriae Young & Geisen, in Young et al. (2003)

Distinguishing features:
Parent taxon (narrow rimmed placoliths): Diverse group of coccoliths with narow placolith rims and variable central structures, usually showing four-fold symmetry.
This taxon: Coccoliths rhombic narrow-rimmed placoliths with four plates in central area

Farinacci & Howe catalog pages: Placorhombus *



Search data:
LITHS: placolith, quadrate, CA: ca_disjunct, plate, closed,
CSPH: tubular, monomorphic,
Lith size: 1.6->2.4µm; Coccosphere size: 35->55µm;
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): at top of No known fossil record modern (100% up, 0Ma, in "Holocene" stage). Data source: Total of range of species in this database

Plot of occurrence data:


Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I. & Ostergaard, J. B. (2003). A guide to extant coccolithophore taxonomy. Journal of Nannoplankton Research, Special Issue. 1: 1-132. gs V O


Placorhombus compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 27-9-2022

Taxon Search:
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Short stable page link: Go to to create a permanent copy of this page - citation notes

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