radiolaria - rads_cenozoic - Siphostichartus corona radiolaria - rads_cenozoic - Siphostichartus corona

Siphostichartus corona


Classification: rads_cenozoic -> Artostrobiidae -> Siphostichartus -> Siphostichartus corona
Sister taxa: S. corona, S. praecorona, S. sp.

Taxonomy

Citation: Siphostichartus corona (Haeckel) Nigrini 1977
taxonomic rank: species
Basionym: Cyrtophormis corona
Synonyms:
1887 Cyrtophormis corona - Haeckel p.1462; pl.77, fig.15
1977 Siphostichartus corona - Nigrini p.257; pl.2, figs.5, 6
Taxonomic discussion: (Haeckel)1887 p.1462 pl.77 fig.15; Riedel & Sanfilippo1971 p.1600; Nigrini 1977; Alexandrovich 1989 (ODP 111 SR) p.256 pl.3 fig.6 (synon)

Catalog entries: Cyrtophormis corona

Original description: Shell smooth, conical, ovate, with three deep strictures, about twice as long as broad. The fourth joint is the broadest, inflated, and three times as long as the second and the third joints. Pores small and numerous, circular, in regular, transverse rows; two in the first joint, four in the second and third, and ten in the fourth joint. Cephalis hemispherical, with a stout, pyramidal horn. Peristome two-thirds as broad as the fourth joint, with twelve to fifteen triangular, convergent teeth.

Length of the shell (with four joints) 160µm, breadth 80µm. Length of the single joints, a 10, b 30, c 30, d 90µm.
Remarks on original description: Haeckel listed Cyrtophormis corona under the subgeneric name Acanthocyrtis, but did not include the subgeneric name in the species name. This species is assigned to Acanthocyrtis (the junior homonym) Haeckel, 1887a (non Haeckel, 1881a).]

Description


Published descriptions


Nigrini 1977 - Cyrtophormis corona

Description: Shell smooth, hyaline, conical, compressed laterally. Cephalis hemispherical with a few circular pores, well-developed three-bladed apical horn, and prominent, duck-billed vertical tube; apical spine free of cephalic wall and axial rod well developed. Thorax inflated, slightly heavier than the rest of the shell; two or three transverse rows of circular pores. Abdomen inflated conical with four to seven transverse rows of circular pores. Fourth segment considerably larger than the others, usually contracting distally and without a differentiated peristome; numerous widely spaced transverse rows of small circular pores. Termination ragged or shell may terminate along a pore row. thus giving the appearance of small terminal teeth (cf. Riedel and Sanfilippo. 1971. p. 1600). Intersegmental strictures curved, not pronounced internally.

Dimensions: Total length (excluding apical horn) 135- 190: length of abdomen 30-40µ: length of fourth segment 70-105µ; maximum breadth (across fourth segment) 70-95µ. Range and abundance: Rare at time of first appearance in the Stichocorys wolffii Zone; few to common from Dorcadospyris alata Zone to Ommatartus penultimus Zone; last rare occurrences in the Stichocorys peregrina Zone. Phylogeny: Appears to have developed from Siphostichartus praecorona in whi ch the third segment has only two rows of pores and a less prominent apical horn and vertical tube.

Remarks: Petrushevskaya and Kozlova (1972. p. 538) have described a similar form, Theocamptra spirocyrtis. In the present study no specimens quite like it have been observed.


Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within Neogene Period (2.59-23.03Ma, top in Piacenzian stage). Data source: Lazarus et al. 2015 - "N age group"
First occurrence (base): within Neogene Period (2.59-23.03Ma, base in Aquitanian stage). Data source: Lazarus et al. 2015 - "N age group"

Plot of occurrence data:

References:

Alexandrovich, J. M. (1989). Radiolarian biostratigraphy of ODP Leg 111, Site 677, eastern equatorial Pacific, late Miocene through Pleistocene. Proceedings of the Ocean Drilling Program, Scientific Results. 111: 245-262. gs

Haeckel, E (1887). Report on the Radiolaria collected by H.M.S. Challenger during the years 1873-1876. Report on the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-1876. 18: 1-1803. gs O

Nigrini, C. A. (1977). Tropical Cenozoic Artostrobiidae (Radiolaria). Micropaleontology. 23(3): 241-269. gs

Riedel, W. R. & Sanfilippo, A. (1971). Cenozoic Radiolaria from the western tropical Pacific, Leg 7. Initial Reports of the Deep Sea Drilling Project. 7: 1529-1666. gs


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Siphostichartus corona compiled by the radiolaria@mikrotax project team viewed: 2-3-2024

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