Bekoma demissa


Classification: rads_cenozoic -> Theoperidae -> Bekomidae -> Bekoma -> Bekoma demissa
Sister taxa: B. bidartensis, B. campechensis, B. demissa, B. divaricata, B. helenae, B. oliva, B. sp.
Daughter taxa: (blue => in age window 0-800Ma)
Bekoma demissa demissa

neptune records: 4
Bekoma demissa robusta

neptune records: 15

Taxonomy

Citation: Bekoma demissa Foreman 1973
Rank: species
Basionym: Bekoma demissa

Catalog entries: Bekoma demissa

Original description: Cephalis subspherical, apparently partly depressed in the thorax, with small, circular pores overall and bearing two, apical and vertical, slender, rodlike horns which may be ridged basally. Thorax subhemispherical with regularly arranged, uniform, circular pores and surface slightly roughened by small pointed nodes. Thorax inflated between indentations that mark the line of internal ribs from the primary lateral and dorsal bars to the three feet. This inflated thorax partly obscures the collar stricture, which has five collar pores internally the vertical bar rising so sharply that it does not divide the cervical pore A smooth rim surrounds the slightly constricted aperture. Three feet, trian-gular to subtriangular in cross section, extend downward from the distal-most thoracic wall, with very little divergence except distally where they curve outward and terminate in smooth points. The feet may be entirely -smooth or have one or two lateral thorns or short branches distally; these have never been observed to join the branches of the adjacent feet.

(Based on 20 specimens) Length of cephalis and thorax 125-155µm, width of thorax 125-155µm. Distinguishing characters (rw): This species is distinguished from Bekoma campechensis and B. divaricata by the character of the cephalis which differs in having numerous pores overall, has collar structures which differ somewhat (see Figure 6), and appears partly depressed in the thorax, and also by the feet which depend with very little divergence and have less well-developed branches. Although this species appears to be related to B. campechensis and B. divarciata, the considerable difference between its cephalis and that of the type species of Bekonia (Bekoma bidarfensis) makes the generic assignment doubtful.

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"

Plot of occurrence data:

References:


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Bekoma demissa compiled by the radiolaria@mikrotax project team viewed: 22-10-2020

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Short stable page link: http://mikrotax.org/radiolaria/index.php?id=203309 Go to Archive.is to create a permanent copy of this page - citation notes



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