CATALOG OF ORIGINAL DESCRIPTIONS: Sethopyramis magnifica 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 -> Sethopyramis -> Sethopyramis magnifica
Other pages this level: S. acuticephala, S. akanthodes akanthodes, S. akanthodes leptopleura, S. aneotos, S. bicornis, S. cyclomma, S. dodecalactis, S. enneactis, S. fenestrata, S. hexagonalis, S. hexalactis, S. lucerna, S. magnifica, S. maxima, S. pulcherrima, S. quadrata [sec. junior hom], S. scalariformis, S. septimoangularis, S. spinosa, S. trapezoides, S. victori

Sethopyramis magnifica

Citation: Sethopyramis magnifica Clark & Campbell 1942
Rank: species
Type specimens: pl.8, figs.1,5,9
Type repository: University of California, Museum of Paleontology, San Francisco
Described on page(s) : p.72
Family (traditional): Theoperidae
Family (modern): Acropyramiidae

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Current identification:


Original Description
Shell smooth, broadly pyramidal; cephalis very small, like a tiny knob, subglobose, hyaline, and entirely poreless, with a distinct collar stricture; thorax a stout, well-built pyramid with nine (or ten) flat, subequal, triangular, plane faces, the cephalic 0.3 of the pyramid about 43°, and the distal section about 20°, the change in contour between the two sections fairly sudden but without angulation, the thorax composed of ten (or eleven) strong, fairly straight radial beams, these beams connected at fairly regular intervals by eight to twelve horizontal cross-bars, each plane face forming a ladderlike structure, the areas enclosed by beams and cross-bars forming quadrangular meshes (these meshes apparently double-contoured in the photographed specimens, although actually this is an optical effect not apparent from the specimen itself), these meshes mostly subuniform but increasing in size along the length of the face, some of them, however, in the cephalic portion rounded, and others, especially in the lower or distal thorax, more or less squarish or even elongate, here and there an irregular, rare, larger one with the cross-beams not strictly in the proper row, in some but apparently not in all specimens (possibly only aged individuals) a secondary mesh or arachnoidal network enclosed by the meshes of the cephalic 0.5 of the thorax much as in Spongopyramis (vel Plectopyramis) spongiosa (Haeckel, p. 1261, pl. 56, fig. 10). Individuals with the arachnoidal network also have the lower meshes with minute, conical teeth on the framework.

Length of shell, 60 (broken individual ?) -180µm; of cephalis, 10µm; breadth, maximum, 100-110µm. Distinguishing characters (rw): Sethopyramis magnifica n. sp. differs from S. quadratella (Ehrenberg 1875) = Cornutella quadratella (Barbados) in smaller cephalis, which is also poreless unlike that species, and in rather different mesh. The loss of the already greatly reduced cephalis would result in Bathropyramis (Monocyrtoidea), which genus differs from Sethopyramis only in lacking this organ and suggests very strongly the origin of that genus from this or some closely related, perhaps earlier, allied species. The presence of an arachnoidal network in some of the meshes of this species suggests relationship to Spongopyramis, a rare, exclusively recent genus from the tropical Pacific.
A single specimen of another species of Sethopyramis was found in a smear slide at loc. A-2829. This specimen had a greatly enlarged spongy cephalis, and also the radial beams and crossbars were very strong and coarse.

Editors' Notes
[The authors here list this species under the subgeneric name Cephalopyramis and include the subgeneric name in the species name.

References:

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


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Sethopyramis magnifica compiled by the radiolaria@mikrotax project team viewed: 25-2-2021

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