radiolaria - rads_cat - Theocyrtis diabloensis

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Theocyrtis diabloensis

Citation: Theocyrtis diabloensis Clark & Campbell 1942

Type repository: University of California, Museum of Paleontology, San Francisco

Family (traditional): Pterocorythidae

Family (modern): Pterocorythidae

Shell small, apically strongly pointed and with two swollen, ringlike segments below the conical cephalis; apical horn much reduced as a mere equally four-angled, sharp point; cephalis acuminate (40°), its length less than 0.22 total length, the apex narrowly rounded over, the sides nearly plane, mostly symmetrical, the basal diameter nearly 1.2 times the height, with very little change in contour between it and the thorax; thorax conical-ring shaped (16°), about 0.27 total length, the basal diameter 1.5 times the diameter at the base of the cephalis, the sides strongly bulged, much resembling a wide, old-fashioned wedding ring; the bulge at the middle equals the basal diameter, the base, however, very sharply constricted at the internal, septal ring which marks off its lower margin from the abdomen; abdomen similar to thorax in general shape, its middle being only a trifle wider than the thoracic bulge, the apertural end, however, having a diameter of 0.28 total length; aperture margin torn, possibly irregular, not toothed; wall fairly thick, outwardly smooth, as a whole neatly trim; surface of horn, hyaline; of cephalis, hyaline with only a very few, tiny, circular pores near the upper part; of thorax, with about sixty, subequal, double-contoured, circular, very well-spaced pores; of abdomen, with about the same number of pores as the thorax or, perhaps, a few less, these pores larger than those of thorax but otherwise similar, the pores of both thorax and abdomen tending to be mildly spiralled (about 5°) in subregular tiers; framework, dark, gray, dense.

Length of shell, 145µm; of horn and cephalis, 32.0µm; of thorax, 40.8µm; diameter of base of cephalis, 38.6µm; of septal ring, 60.6µm; of pores, 2.2-6.6µm.

Distinguishing characters: Theocyrtis diabloensis n. sp. differs from T. barbadensis Haeckel (1887) = (Ehrenberg, 1875, Eucyrtidium barbadense) in reduced apical horn and differently shaped thorax.

[The authors here list this species under the subgeneric name Theocorypha and include the subgeneric name in the species name.

References:

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

CATALOG OF ORIGINAL DESCRIPTIONS: Theocyrtis diabloensis Clark & Campbell 1942

Theocyrtis diabloensis

References:

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