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Antarctissa denticulata
(Ehrenberg, 1844)
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Description - Add description
Lithobotrys(?) denticulata
Lorica ovata ampla late porosa (poris in 1/100''' 2—3.) subtriloba, utrinque rotundata nec truncata, denticulis undique bispida, apertura obsoleta.
Longit. 1/22'''
Habitus Lithocampae, sed nulli articuli. Structuram internam spiralem esse suspicor. Quae pars anterior quae posterior jure habeatur in toto genere non liquet.
| | Ehrenberg 1844 | Pylospyris denticulata
Shell spinulate, with slight coronal and deep sagittal constriction, with irregular, roundish pores of variable size. Galea hemispherical, about half as long and broad as the nut-shaped cephalis. No symmetrically disposed larger pores.
Dimensions.-Galea 0.04 long, 0.06 broad; cephaiis 0.08 long, 0.1 broad.
Habitat.-Antarctic Ocean, Ehrenberg. (Included in the ice.)
| | Haeckel 1887 | Peromelissa denticulata
Schale kegelförmig mit nahezu kreisförmigem Querschnitt, durch eine quere Einschnürung in einen kleineren Abschnitt (Cephalis) und einen größeren (Thorax) geteilt. Letzterer meist durch deutliche Longitudinalfurchen in 3 Loben zerlegt. Wandung der Schale dick, mit unregelmäßigen, rundlichen Poren, welche meist schmäler als die da- zwischen liegenden Balken sind, an der Außenseite mit kräftigen Dornen besetzt, welche an der Cephalis apicalwärts, am Thorax, insbesondere an dessen basalem Rande, basalwärts gerichtet sind. Basale Gitterplatte des Thorax dünnwandiger als die übrige Schale, ohne Dornenbesatz.
Das Innenskelett besteht aus drei bandförmigen, dichotomisch verzweigten Querbalken welche zwischen Cephalis und Thorax gelagert sind und von einem gemeinschaftlichen Centrum radiär gegen die Longitudinalfurchen ausstrahlen. Ihren Ansatzstellen können an der Außenfläche der Schale kleine Höcker entsprechen. Von dem Centrum erstreckt sich ein Achsenstab durch den Thorax nach der Basalplatte. Der Achsenstab kann die Basalplatte erreichen oder er ist rudimentär und hängt frei in die Thoraxhöhle herab.
Höhe der Schale 0,11 —0,12, größte Breite 0,08 —0,1 mm.
| | Haecker 1908 | Antarctissa deflandrei
Skeleton massive, with characteristic contour of equilateral triangle. First segment small, sunk deeply into expanded second segment. Width of second segment 1.5-1.8 times that of first. Widest part of shell is lower part of second segment. "Thorax" closed below by thick porous plate. Pores on shell rounded, disposed irregularly; on second segment on pores somewhat larger than on first. Walls of shell very thick, therefore pores form funnel-shaped structure. Surface of shell uneven, with spines. Particularly long spines disposed on lower edge of shell. Needles of internal skeleton A, Vert, D, Lr and Ll very closely adjacent to walls of shell. Their extensions to outside of shell barely discernible.
Dimensions: length of first segment (externally) 35-50µ, width 65-80µ, length of second segment 70-90µm, width 90-150µ.
Location. Found in the Antarctic by Ehrenberg (1844), then by Haecker (1907, 1908) in plankton in the 4,000-5,000-m horizon (stations 143 and 147 of the "Valdivia"). Popovskii (1908) found one specimen at the 0-385m horizon. In Antarctic sediments found by Riedel (1958) at stations 30, 42, 47, 94, 97, and 103 of BANZARE. In our material encountered in samples of sediments at all stations (Figure 92, I) in Indian and Pacific Ocean sectors. In coastal regions in zone of iceberg sediments shells of A. denticulata constitute from 3 to 24% (in the shelf sediments 3-5%) of total number and in zone of oceanic diatomaceous ooze their proportion reaches 20-30%. This species is the most abundant and characteristic of radiolarians in the deepwater Antarctic sediments. Outside the Antarctic, single specimens of this species are encountered as exceptions in foraminiferous ooze (Figure 92. I).
Note. A. denticulata is a sufficiently clearly outlined, characteristic, and easily distinguished species. The size of the shell, disposition and size of the pores vary widely; the general form of the shell is very consistent. It is possible to isolate several varieties of A. denticulata apart from the type species described above according to this feature.
| | Petrushevskaya 1967 |
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