rad_org Lophocyrtis semipolita img1171.jpg
rad_org Lophocyrtis semipolita img1431.jpg
rad_org Lophocyrtis semipolita img1432.jpg
rad_org Lophocyrtis semipolita img1433.jpg
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rad_org Lophocyrtis semipolita img2380.jpgCatalog entries: Calocyclas semipolita semipolita
 semipolita semipolita Clark and Campbell 1942.jpg)
type material: C. semipolita semipolitaOriginal description: 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.
Remarks on original description: [The authors here list Calocyclas rachiphora under the subgeneric name Calocycletta and include the subgeneric name in the species name.
not known - radiolaria.org gave Clark & Campbell 1942 but this is not the text from there. - Calocyclas semipolita Shell having small knoblike cephalis and abdomen with tiny, terminal feet; cephalis subglobular and tightly pinched off from the thorax, its apex armed with a needlelike and often basally ribbed apical horn; thorax hemispherical, large, strongly convex in lateral contour, and proximally limited by a septal band; abdomen subcylindrical or convex, sometimes contracted toward the aperture or even swollen in in the middle; aperture with ten to a dozen similar teeth; cephalis having small hexagonal areas bounded by ridges; wall of thorax with circular, closely set pores and having sepaloid points between the pores, the pores being set into concave areas; wall of abdomen havinglarge, well-spaced, dissimilar pores.
Published descriptions
Similar species
Geological Range:
Last occurrence (top): within Paleogene Period (23.03-66.04Ma, top in Chattian stage). Data source: Lazarus et al. 2015 - "P age group"
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Lazarus et al. 2015 - "P age group"
Plot of occurrence data:
Abelmann, A. (1990). Oligocene to Middle Miocene radiolarian stratigraphy of southern high latitudes from Leg 113, Sites 689 and 690, Maud Rise. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 675-708. gs 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 Sanfilippo, A. & Caulet, J. (1998). Taxonomy and evolution of Paleogene Antarctic and tropical Lophocyrtid radiolarians. Micropaleontology. 44(1): 1-43. gs Weaver, F. M. (1983). Cenozoic radiolarians from the southwest Atlantic, Falkland Plateau region, Deep Sea Drilling Project Leg 71. Initial Reports of the Deep Sea Drilling Project. 71: 667-686. gs Missing or ambiguous references: Chen 1975; Clark & Campbell 1942; ; References:
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Lophocyrtis semipolita compiled by the radiolaria@mikrotax project team viewed: 20-5-2026
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