CATALOG OF ORIGINAL DESCRIPTIONS: Lithatractus pterosphaerus 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 -> L -> Lithatractus -> Lithatractus pterosphaerus
Other pages this level: L. birostratus, L. carduelis, L. cirsium, L. conifer, L. conostylus, L. convallaria, L. echiniscus, L. floridus, L. fragilis, L. gamoporus, L. hederae, L. hexagonalis, L. jugatus, L. leptostylus, L. lobatus, L. miocaenica, L. nucleolus, L. nuphar, L. pachystylus, L. pierinae, L. pterosphaerus, L. rosetta, L. santaeannae, L. santaeannae pusillus, L. timmsi, L. timmsi quadrispinus

Lithatractus pterosphaerus

Citation: Lithatractus pterosphaerus Clark & Campbell 1942
Rank: species
Type specimens: pl.5, fig.22
Type repository: University of California, Museum of Paleontology, San Francisco
Described on page(s) : p.33
Family (traditional): Actinommidae
Family (modern): Stylosphaeridae

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Current identification:

Original Description
Shell small, with two opposite polar spines, these spines conical (8°), equally four-angled with slightly concave interfaces, the blades being triangular with the broad bases widest, the tips nlunted, spines as long as the radius of the cortical shell, and with basal diameters about the same as the diameter of a cortical pore or somewhat more; cortical shell strongly elliptical, widest across the equator where it is 0.85 the long axis, surface relatively smooth and neatly trim, with six pores across the lesser diameter and eight or nine across the long axis, pores very slightly sunken into obscured subhexagonal areas with weak sepaloid conules, these points hardly affecting the external contour, pores subcircular, their e”dges slightly crinkled; framework dense, thick; medullary shell small, strongly elliptical, with eight pores across the long axis and six across the short axis, these pores subhexagonal, small, framework rather thin, brownish; supporting beams six, two polar and four equatorial, polar beams strongest.

Length of polar spines, 40.8µm; diameter of the two axes of the cortical shell, 93.6 and 92.6µm respectively; of medullary shell, 32.0 and 43.0µm respectively; of cortical pores, 10µm; width of cortical wall 6.6µm. Distinguishing characters (rw): Lithatractus pterosphaerus n. sp. differs from L. hederae n. sp. in generally different shape of the cortical shell, usually shorter polar spines, and in dimensions.

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


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


Lithatractus pterosphaerus compiled by the radiolaria@mikrotax project team viewed: 20-4-2021

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