CATALOG OF ORIGINAL DESCRIPTIONS: Sethopilium heterope Clark & Campbell 1942

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.

Higher levels: rads_cat -> S -> Sethopilium -> Sethopilium heterope
Other pages this level: S. cyrtopus, S. heterope, S. macropus, S. orthopus

Sethopilium heterope

Citation: Sethopilium heterope Clark & Campbell 1942
Rank: species
Type specimens: pl.9, fig.31
Type repository: University of California, Museum of Paleontology, San Francisco
Described on page(s) : p.69
Family (traditional): Theoperidae
Family (modern): Lychnocaniidae

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Current identification:

Original Description
Shell with distinct cephalis and thorax, apical horn lacking; cephalis as long as wide, cap-shaped, distally rounded, basally rather sharply set off from the thorax, possibly three-angled like the thorax, which is truncate-conical, with strongly convex bosoms reaching the maximum diameter toward the middles, and as a whole reaching its maximum diameter at the level of the origin of the feet, near its broad base, thence contracting very rapidly to the flat apertural face; feet three, equidistant, equal, continued from three thin, narrow, external, more or less discontinuous ribs or ridges along the surface of the thorax and marking off the bosoms from each other, the ridges originating at the cephalic stricture, free portion of feet angled at the bases, not very wide at their origins, conical distally (broken off in the photographed specimen but apparently straight, and almost certainly divergent); aperture relatively wide, simple; wall thick; surface of cephalis, with a few, extremely small, well-scattered, round pores; of thorax, with subcircular, subequal, fairly well spaced pores in more or less regular vertical lines or rows, at least twenty pores in a bosom, with small, blunted, angular sepaloid point at the angles of the obscure subhexagonal areas.

Length of shell, 82.6µm; of cephalis, 23.2µm; breadth of top of thorax, 25.4µm; of maximum of shell, 76.0µm; of aperture, 43.0µm; diameter of pores of thorax, 4.4µm. Distinguishing characters (rw): Sethopilium heterope n. sp. differs from S. macropus Haeckel (1887) in its shape and general appearance, especially of the bosoms and the pores, from S. orthopus Haeckel (1887), chiefly in the character of the apertural region, and from S. cyrtopus Haeckel (1887), in the pores of the cephalis, regularity of thoracic pores, and curvature of ribs. It is not especially close to these three recent, Pacific species but has obvious relations to them.


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


Sethopilium heterope compiled by the radiolaria@mikrotax project team viewed: 25-2-2021

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