radiolaria - rads_cenozoic - Saccospyris conithorax

Saccospyris conithorax


Classification: rads_cenozoic -> Cannobotryidae -> Cannobotryidae inc sed -> Saccospyris -> Saccospyris conithorax
Sister taxa: S. antarctica, S. conithorax, S. preantarctica, S. sp.

Taxonomy

Citation: Saccospyris conithorax Petrushevskaya 1965
Rank: species
Basionym: Saccospyris conithorax
Taxonomic discussion: Petrushevskaya 1965 Petrushevskaya (1971a)

Catalog entries: Saccospyris conithorax

Original description: S. conithorax differs from the preceding species [S. antarctica] by a nearly ellipsoidal shell with thinner walls. Small crests, or protuberances, and other ornamentations are sometimes observed on the surface of the upper part of the second segment, but they do not exist on the other parts of the shell which is smooth. The cephalic and ante-cephalic chambers have nearly the same dimensions, but the ante-cephalic chamber is sometimes larger than the cephalic. The post-cephalic chamber is not so much developed and not so distinct from the second segment of the shell. The different elements of the internal skeleton are usually more visible than in S. antarctica. The shell wall is thinner and smoother.
In adults, the second segment is often closed with, either an elongated and conical basis (fig.11, I, II), either an almost flat basis (fig.11, III and VI). Between these two morphologies, different transitional structures can be observed (fig.11, IV). We consider that the conical shape is more typical. On the lower part of the second segment are distributed the larger pores, sometimes in transversal rows (fig.11, I). At the very end of the shell, there is, usually, a large pore (fig.11, VI).

Length of first segment, nearly 30µm. Length of second segment 40-60µm. Total length 70-90µm, along the sagittal axis 60-70µm, along the frontal axis, nearly 40µm. Distinguishing characters (rw): In the Antarctic sediments, some shells resembling that of S. antarctica are frequently found They differ, however, by smaller dimensions and morphological differences. After his observations, Riedel placed them in the S. antarctica group. We followed the same way at the beginning, but it appeared that two groups of forms, with many different characteristics and having no transitional forms could be found. We come, now, to the conclusion that these two groups could be distinguished as two different species.
Remarks on original description: Frequent in Antarctic sediments, but it is, for the moment, difficult to precise if this form is restricted to this area. Not observed in tropical and sub-tropical areas. W.R. Riedel (1958) has reported shells similar to his Saccospyris (= Botryopyle) antarctica from the northern Pacific Ocean, but he did not give any description or illustration of them. As far as we know the radiolarians of this area (Kruglikova’s collections); we consider that no typical representatives of S. antarctica can be found. Some forms similar to representatives of S. conithorax with a flattened basal second segment can be observed (fig.11, VI).

Description


Morphology:


Size:

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): Extant. Data source: Lazarus et al. 2015 - "R age group"
First occurrence (base): within Quaternary Period (0.00-2.59Ma, base in Gelasian stage). Data source: Lazarus et al. 2015 - "R age group"

Plot of occurrence data:

References:

Petrushevskaya, M. G. (1965). Osobennosti Konstruksiy skeleta Radiolyariy Botryoidae (Otr. Nassellaria). Trudyi Zoologicheskogo Instituta, Akademiya Nauk, SSSR. 79-118. gs


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Saccospyris conithorax compiled by the radiolaria@mikrotax project team viewed: 4-7-2022

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