Pemma


Classification: Coccolithophores -> Braarudosphaerales -> Braarudosphaeraceae -> Pemma
Sister taxa: Braarudosphaera, Hexadelus, Micrantholithus, Pemma, Pentaster,

Daughter taxa: (blue => in age window 0-800Ma)
Pemma with crenulate edges.
Large, circular Pemma with a diagnostic thin base with crenulated edges. Central area consists of a layer of basal thickenings superimposed on the base, resulting in a hazy appearance of the outer edge of the nannolith and a central area more highly birefringent than the edges.
Pemma with multiple nodes along the outer margin of each pentalith.
Circular Pemma species
Angular Pemma species with ray tips extending beyond the pentagonal periphery
Relatively large (typically >5 µm), triangular-shaped nannoliths that thicken along the longer sides and exhibit low birefringence in XPL.
Large (typically >7 µm), triangular-, rectangular- or rhomb-shaped nannoliths, which are thickened along two sides (‘base’ and ‘side’) to give a hook-shaped appearance. Dark in XPL but birefringent where thickened; c-axis orientation is parallel with the long axis.
Specimens which cannot be assigned to any established species

Taxonomy:

Citation: Pemma Klumpp, 1953
Rank: Genus
Type species: Pemma rotundum Klumpp, 1953

Distinguishing features: Pentaliths with a central depression/perforation in each segment; often producing elevated, robust structures that are commonly observed in side view.

Farinacci & Howe catalog pages: Pemma *

Search data:
TagsLITHS: nannolith-radiate, pentagonal, RIM: tips-bifurcate, CA: pores,
CSPH: not known, T-UNITS: all,
MetricsLith size: 5->18µm; Segments: 5->5;
Sources:
The morphological data given here can be used on the advanced search page. See also these notes

Geological Range:
Last occurrence (top): in lower part of Rupelian Stage (17% up, 32.9Ma, in Rupelian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Lutetian Stage (0% up, 47.8Ma, in Lutetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

References:


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Pemma compiled by Jeremy R. Young, Paul R. Bown, Jacqueline A. Lees viewed: 14-11-2019

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Short stable page link: http://mikrotax.org/Nannotax3/index.php?id=1034 Go to Archive.is to create a permanent copy of this page - citation notes



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