radiolaria - rads_cat - Stichomitra asymmetra radiolaria - rads_cat - Stichomitra asymmetra

CATALOG OF ORIGINAL DESCRIPTIONS: Stichomitra asymmetra Foreman 1978

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 -> Stichomitra -> Stichomitra asymmetra
Other pages this level: S. asymbatos, S. asymmetra, S. communis, S. compsa, S. wero

Stichomitra asymmetra

Citation: Stichomitra asymmetra Foreman 1978
Taxonomic rank: species
Described on page(s) : p.748
Type specimens: pl.5, fig.2
Type age (chronostrat): Late Cretaceous, Mesozoic
Type locality: LD210
Type repository: Holotype, USNM 243118, U.S. National Museum, Washington, D.C.
Repository city: Washington

Current identification:


Original Description

Shell of from five to eight segments plus a short narrow fragile tube. The first three to four segments are conical and the remainder cylindrical with the last segment before the tube generally slightly narrowed and less sturdy than the preceding segments. The small cephalis may bear a short slender apical horn or have the cephalic wall thickened at the apex. The lumbar stricture is generally not horizontal and thus the cephalis and thorax frequently appear askew. Cephalis and thorax are both poreless except for an occasional specimen which may have a few pores at the lumbar stricture. The remaining segments have small, widely spaced, rounded pores, generally irregularly arranged and recessed in angular frames. These frames result in a rough surface and on the distal segments give rise to nodes or occasional downward directed spines at their junctures. The tube is frequently broken off, but when present is thin-walled with rounded pores, irregularly arranged or tending toward transverse alignment.

Size:
(based on 10 specimens). Length of longest complete specimen 130µm, of five segments 85-100µm; greatest width 50-70µm, width of tube 30-35µm.

Etymology:
From the Greek adjective asymmetros, without symmetry.

Extra details from original publication
Distinguishing features: A related form (Plate 5, Figure 1) from the California Academy of Science locality 39545 Alameda Co., California, differs in having more closely spaced, more numerous pores without frames and thus a smoother surface. These specimens also tend to have more

References:

Foreman, H. P. (1978b). Mesozoic Radiolaria in the Atlantic Ocean off the northwest Coast of Africa, Deep Sea Drilling Project, Leg 41. Initial Reports of the Deep Sea Drilling Project. 41: 739-761. gs


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Stichomitra asymmetra compiled by the radiolaria@mikrotax project team viewed: 25-6-2025

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