radiolaria - rads_cenozoic - Theocyrtis robusta radiolaria - rads_cenozoic - Theocyrtis robusta

Theocyrtis robusta

Classification: rads_cenozoic -> Pterocorythidae -> Theocyrtis -> Theocyrtis robusta
Sister taxa: T. annosa, T. careotuberosa, T. diabloensis, T. litos, T. perpumila, T. perysinos, T. robusta, T. setanios, T. tuberosa, T. sp.


Citation: Theocyrtis robusta (Clark andCampbell) Caulet 1991
taxonomic rank: species
Basionym: Calocyclas semipolita robusta
Taxonomic discussion: (Clark &Campbell) 1942; Caulet 1991

Catalog entries: Calocyclas semipolita robusta

Original description: Shell short and squat, with equal thorax and abdomen; cephalis knoblike, sub-globular (0.5 length of horn) with rather less tightly pinched off base than in C. semipolita semipolita n. subsp., its sides a little convex and subparallel, its apex with a relatively long horn (nearly 0.33 total length), the horn generally conical, the distal 0.67 narrowed, needlelike, the proximal part wider (approximately 10°), circular in section, the tip sharp, the base simply crowning the cephalis without local modification; thorax only about twice the length of the cephalis, very strongly hemispherical, rather clearly symmetrical, with strong, convex sides which reach the greatest diameter at the middle and contract proximally to a narrow, internal band as in C. semipolita semipolita n. subsp., this stricture emphatic of the bulges of both thorax and abdomen below and producing the effect of much greater constriction than actually occurs; abdomen generally convex, only a trifle longer than the thorax (not much longer than the apical horn), with considerable swelling toward the middle as the thorax, with much local swelling and contraction along its length, and with generally subcylindrically contracted aperture, the two sides of the abdomen not locally modified in the same way at the same level; aperture with ten or a dozen, triangular, subequidistant, divergent, rather distinct and fairly large teeth, these teeth more prominent than in C. semipolita semipolita n. subsp.; wall rather thick; other structural characters, especially of the pores, closely resembling those of C. semipolita semipolita n. subsp.
Remarks on original description: [The authors here list this species under the subgeneric name Calocycletta and include the subgeneric name in the species name.


Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Neogene Period (2.59-23.03Ma, top in Piacenzian stage). Data source: Lazarus et al. 2015 - "N age group"
First occurrence (base): within Neogene Period (2.59-23.03Ma, base in Aquitanian stage). Data source: Lazarus et al. 2015 - "N age group"

Plot of occurrence data:


Caulet, J. (1991). Radiolarians from the Kerguelen Plateau, Leg 119. Proceedings of the Ocean Drilling Program, Scientific Results. 119: 513-546. gs

Clark, B. L. & Campbell, A. S. (1942a). Eocene radiolarian faunas from the Mt. Diablo area, California. Geological Society of America, Special Papers. 39: 1-112. gs


Theocyrtis robusta compiled by the radiolaria@mikrotax project team viewed: 18-5-2024

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