Lithocyclia crux


Classification: rads_cenozoic -> Coccodiscidae -> Lithocyclia -> Lithocyclia crux
Sister taxa: L. angusta, L. aristotelis, L. crux, L. ocellus, L. sp.

Taxonomy

Citation: Lithocyclia crux Moore 1971
Rank: species
Basionym: Lithocyclia crux
Taxonomic discussion: Moore 1971 p.737 pl.6 fig.4; Sanfilippo et al. 1985 p.655 figs.7.4a-b

Catalog entries: Lithocyclia crux

Original description: Phacoid cortical shell approximately two to three times as broad as medullary shell with subcircular to irregular pores. Cortical shell may be filled with spongy meshwork. Four arms, approximately perpendicular and in the same plane, are very irregularly pored to form spongy, subcylindrical columns. In rare specimens a spongy patagium is preserved. It connects the base of the arms and is formed parallel to the cortical shell. This species resembles Lithocyclia angustum (Riedel) in all respects except the number of arms.

Based on 30 specimens. Diameter of cortical shell 113-132 µ; of medullary shell (shadowy outline seen through cortical shell) 37-66 µ; Length of arms 75-168 µ; median breadth 22-47 µ. (Moore, 1971)

Diameter of cortical shell 125-150 µ, width of arms medially 20-30 µ. (Sanfilippo et al., 1985) Distinguishing characters (rw): Four narrow spongy arms, approximately perpendicular to each other. (Riedel and Sanfilippo, 1978a)

L. crux is distinguished from L. angusta by having four spongy arms rather than three, and from the L. aristotelis group by the arms being narrower. (Sanfilippo et al., 1985) Phylogeny (rw): This species developed from the L. aristotelis group, and it (or L. angusta) evolved into Didymocyrtis prismatica.
Remarks on original description: This species varies in similar ways to L. angusta, but not to such a great extent. The meshwork of the cortical shell tends to be spongy in early specimens, and more regularly latticed in later ones. Arms vary in width, but have not been observed to be reduced to spines. (Sanfilippo et al., 1985)

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:

Moore, T. C. Jr. (1971). Radiolaria. Initial Reports of the Deep Sea Drilling Project. 8: 727-774. gs

Sanfilippo, A., Westberg-Smith, M. J. & Riedel, W. R. (1985). Cenozoic Radiolaria. In, Bolli, H. M. , Saunders, J. B. & Perch-Nielsen K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge 631-712. gs


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Lithocyclia crux compiled by the radiolaria@mikrotax project team viewed: 27-11-2020

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