radiolaria - rads_cat - Calocyclas semipolita semipolita

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Calocyclas semipolita semipolita

Citation: Calocyclas semipolita semipolita Clark & Campbell 1942

Type specimens: pl.8, figs.12, 14, 17-19, 22, 23

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

Family (traditional): Theoperidae

Shell tall and stately, with small, knoblike cephalis, and abdomen with tiny, terminal feet; cephalis knoblike, subglobular for the most part, rather tightly pinched off from the thorax, sometimes asymmetrical, its apex with a long horn, the horn conical, narrow, generally needlelike, distally sharp and basally not expanded but with a few short riblets around it; thorax more than twice as long as cephalis, hemispherical, fairly symmetrical, sides strongly convex, apically narrowed-truncate at the base of the cephalis, proximally limited by a constricted, narrow, septal band; abdomen generally subcylindrical, at least 0.5 total length except in broken or otherwise unusual individuals, with local more or less minor changes in contour along the sides, tending to become narrowed in its lower 0.25 as an inverted, basal segment of a truncated cone, this conical section frequently asymmetrical; aperture with about a dozen small, triangular points or teeth, the teeth subequal, subequidistant, divergent, and rather inconspicuous; wall rather thick, hyaline; surface of horn, hyaline; of cephalis, with small, adjacent, hexagonal areas bounded by thickened, raised (?) walls, of thorax, with perhaps sixty or more subcircular, uniform, closely set pores, the surface between the pores roughened with sepaloid conules, the pores being set into shallowed, concave areas, the band separating thorax and abdomen, internal, with pores crossing it, of abdomen, with much larger and more irregular pores than thorax, these pores commonly subcircular, sometimes highly irregular, except in the subadjacent conical apertural section where the pores are often smaller than in other portions of the abdomen, the pores generally well spaced, set into the thick wall and with sides like the rim of a dish; aperture the simple opening of the shell; cavity following the contour almost exactly.

Length of shell (all measurements those of the specimen figured in Fig. 23), 260µm; of horn, 60µm; of cephalis, 20µm; of thorax, 50µm; diameter of cephalis at middle, 29.8µm; of thorax at middle, 76µm; of abdomen, 91.4µm; of aperture, 62.8µm; width of band, 6.6µm; diameters of pores 4.4-8.8µm in various parts of the shell.

Distinguishing characters: An extensive suite of shells is illustrated on Plate 8. This suite gives a fair expression of the range and general appearance of the shells of this species, which is also a long-ranging and common one. As may be seen upon inspection of the figures, not only are many individuals imperfect, but there is considerable variation among them. A few are slightly abnormal in one or more characters. The description is largely based upon the most perfect of the writer’s figured specimens (Fig. 23).
Calocyclas semipolita semipolita n. subsp. differs from C. semipolita robusta n. subsp. in generally longer shell, different horn, and in dissimilarity of length between abdomen and thorax.

[The authors here list Calocyclas rachiphora under the subgeneric name Calocycletta 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: Calocyclas semipolita semipolita Clark & Campbell 1942

Calocyclas semipolita semipolita

References:

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