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Ataxiodinium confusum
Ataxiodinium confusum, Versteegh and Zevenboom, 1995
Holotype: Versteegh and Zevenboom, 1995, Pl. I, figs. 1,4,7
Paratype: Versteegh and Zevenboom, 1995, Pl. I, figs. 3,6
Type Locality: Singa Section, Calabria, S Italy
Type stratum: Pliocene
Stratigraphy: Early Zanclean, top NN12 (Zevenboom and Versteegh, in prep) to Middle Piacenzian, top NN16 (Versteegh, 1994).
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Original description: [Versteegh and Zevenboom, 1995, p. 217]:
Diagnosis:
A species of Ataxiodinium with a smooth, spherical to subspherical endophragm. The periphragm is granulate. Dorsally, the periphragm is connected to the endophragm around the archaeopyle margin. Ventrally, the periphragm and endophragm are connected directly opposite the archaeopyle, for an area similar to that on the dorsal side of the cyst. Occasionally, both walls connect elsewhere, giving rise to funnel shaped depressions in the periphragm.
Description:
In most specimens, the endophragm and periphragm only connect mid-dorsally and mid-ventrally. As a result, a continuous circular cavation running from the apex via the lateral sides to the antapex is present. The cyst thus resembles a bisaccate pollen grain in polar or lateral view and resembles a fried egg at ventral view. A dorsal cross-section typically shows a circular periphragm which is seemingly not connected to the also circular endophragm. The diameter of the periphragm is 1.5 to 3 times that of the endophragm. Apart from the dorsal and ventral areas a few minor connections between periphragm and endophragm may occur elsewhere on the cyst. This gives rise to funnel shaped depressions in the periphragm.
The archaeopyle is considered to be precingular, formed by the loss of plate 3''.
Dimensions:
Holotype: diameter endophragm: 22 µm; diameter periphragm: 36 µm.
Size-range: Inner body: 20-22 µm; outer body: 36-40 µm. Specimens measured: 12.
Affinities:
The species differs from Ataxiodinium choanum in having peri- and endophragm connected over a relatively large ventral area opposite to the archaeopyle and by the virtual absence of funnel shaped connections between peri- and endophragm elsewhere on the cyst.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Ataxiodinium confusum Versteegh and Zevenboom in Versteegh, 1995, differs from A. choane in having peri- and endophragm connected over a relatively large ventral area opposite to the archeopyle and by the virtual absence of funnel shaped connections between peri- and endophragm elsewhere on the cyst. The cyst resembles a bisaccate pollen grain in polar or lateral view and a fried egg in ventral view.
Size: overall 36-40 µm, capsule 20-22 µm.
Holotype: Versteegh and Zevenboom, 1995, Pl. I, figs. 1,4,7
Paratype: Versteegh and Zevenboom, 1995, Pl. I, figs. 3,6
Type Locality: Singa Section, Calabria, S Italy
Type stratum: Pliocene
Stratigraphy: Early Zanclean, top NN12 (Zevenboom and Versteegh, in prep) to Middle Piacenzian, top NN16 (Versteegh, 1994).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Versteegh and Zevenboom, 1995, p. 217]:
Diagnosis:
A species of Ataxiodinium with a smooth, spherical to subspherical endophragm. The periphragm is granulate. Dorsally, the periphragm is connected to the endophragm around the archaeopyle margin. Ventrally, the periphragm and endophragm are connected directly opposite the archaeopyle, for an area similar to that on the dorsal side of the cyst. Occasionally, both walls connect elsewhere, giving rise to funnel shaped depressions in the periphragm.
Description:
In most specimens, the endophragm and periphragm only connect mid-dorsally and mid-ventrally. As a result, a continuous circular cavation running from the apex via the lateral sides to the antapex is present. The cyst thus resembles a bisaccate pollen grain in polar or lateral view and resembles a fried egg at ventral view. A dorsal cross-section typically shows a circular periphragm which is seemingly not connected to the also circular endophragm. The diameter of the periphragm is 1.5 to 3 times that of the endophragm. Apart from the dorsal and ventral areas a few minor connections between periphragm and endophragm may occur elsewhere on the cyst. This gives rise to funnel shaped depressions in the periphragm.
The archaeopyle is considered to be precingular, formed by the loss of plate 3''.
Dimensions:
Holotype: diameter endophragm: 22 µm; diameter periphragm: 36 µm.
Size-range: Inner body: 20-22 µm; outer body: 36-40 µm. Specimens measured: 12.
Affinities:
The species differs from Ataxiodinium choanum in having peri- and endophragm connected over a relatively large ventral area opposite to the archaeopyle and by the virtual absence of funnel shaped connections between peri- and endophragm elsewhere on the cyst.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Ataxiodinium confusum Versteegh and Zevenboom in Versteegh, 1995, differs from A. choane in having peri- and endophragm connected over a relatively large ventral area opposite to the archeopyle and by the virtual absence of funnel shaped connections between peri- and endophragm elsewhere on the cyst. The cyst resembles a bisaccate pollen grain in polar or lateral view and a fried egg in ventral view.
Size: overall 36-40 µm, capsule 20-22 µm.