Bekoma divaricata


Classification: rads_cenozoic -> Theoperidae -> Bekomidae -> Bekoma -> Bekoma divaricata
Sister taxa: B. bidartensis, B. campechensis, B. demissa, B. divaricata, B. helenae, B. oliva, B. sp.

Taxonomy

Citation: Bekoma divaricata Foreman 1973
Rank: species
Basionym: Bekoma divaricata
Taxonomic discussion: Foreman 1973 p 433 pl 3 fig 23 pl 10 figs 3-4; Blome 1992 (ODP 122 SR) p 644 pl 4 fig 13

Catalog entries: Bekoma divaricata

Original description: Shell of two segments with three feet sometimes bearing downwardly directed branches. Cephalis similar to that of Bekoma campechensis. Collar stricture not defined externally, contour of cephalis merging with that of thorax. Thorax proximally poreless, narrow, neck-like, its poreless portion shorter than for B. carnpechensis distally sub-hemispherical, tending to be almost rectangular in longitudinal section. Subbemispherical portion with subcircular pores which may be uniform in size and arrangement or more irregular. Specimens with uniform pores tend to have a surface with tuberculate nodes and those with more irregular pores a surface with sharper nodes. Fragments of lamellar lattice rarely extend below the wide, open aperture. Three slender, smooth, widely divergent, pointed feet, subtriangular in cross section, depend from the shell immediately above the smooth apertural rim. Distally they generally curve outward. Unlike B. campechensis the bran-ches on the distal portion are not uniformly developed and they have never been observed to form a complete triangular ring. A specimen may have no branches, a branch on one foot and not on another, one on each foot, or two at different levels on the same foot. Some branches bifurcate; however, because of their fragmentary nature it is not certain if this is always the case.

(Based on twenty specimens) Length of cephalis and thorax together 95-120µm (majority 100-110µm); width of thorax 110-125µm; length of feet 135-355µm. Distinguishing characters (rw): This species differs from B. campechensis in the shorter length of the cephalis and thorax with the poreless portion of the thorax markedly shorter; and the more slender, widely divergent, smooth feet, which are not uniformly branched and generally curve outward distally.
Remarks on original description: [A name for Bekoma sp. Riedel and Sanfilippo, 1971]

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:

Blome, C. D. (1992). Radiolarians from Leg 122, Exmouth and Wombat Plateaus, Indian Ocean C.D. Blome. Proceedings of the Ocean Drilling Program, Scientific Results. 122: 633-652. gs

Foreman, H. P. (1973a). Radiolaria of Leg 10 with systematics and ranges for the families Amphipyndacidae, Artostrobiidae, and Theoperidae. Initial Reports of the Deep Sea Drilling Project. 10: 407-474. gs


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

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