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Ataxiodinium scaldemense
Ataxiodinium scaldemense, Louwye, 2001, p. 123, fig.3, nos.1-12.
Holotype: Louwye, 2001, fig.3, nos.1-4.
Occurrence: Lower - Middle Miocene (Kiel Sands, Antwerpen Sands and Zonderschot Sands of the Berchem Formation) of northern Belgium as Tectatodinium sp. 1 (Louwye in press, Louwye et al. 2000); Middle - Late Miocene of the Norwegian Sea as Tectatodinium sp. 4 in Manum et al. (1989).
Age: Early-Mid Miocene.
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Original description: [Louwye, 2001]:
Diagnosis:
Small to intermediate, cavate cyst with an ellipsoid ambitus. The endoblast is formed by a solid pedium ornamented with low muri which form an incomplete microreticulum with irregular lumina. The periblast is a variably perforate tegillum which is randomly attached to the endoblast through irregular funnel shaped invaginations. The size and shape of the thin-walled periblast perforations are extremely variable in each specimen.
The archeopyle is formed by the release of the third precingular plate. The operculum is free.
Description:
The thickness of the solid pedium with muri is less than 0.3 μm. The microreticulate ornamentation formed by the low muri of the endoblast is difficult to discern under light microscopy. The number of attachments of the periblast to the endoblast is highly variable and appears random. The separation between endoblast and periblast is 4 μm at maximum. The circular to irregular ellipsoidal perforations of the periblast vary from less than 0.2 μm to maximum 5 μm.
The precingular archeopyle (type P) has smooth margins and straight angles; it is the only indication of a tabulation as no accessory sutures were observed.
Dimensions:
Holotype: length periblast 46 μm, equatorial width periblast 34 μm, average separation between endoblast and periblast: 3 μm.
Range: length periblast: 36 (43) 52 μm, equatorial width periblast: 28 (35) 42 μm, mean separation between periblast and endoblast: 2.9 μm. Number of specimens measured: 11.
Affinities/Comparison:
Ataxiodinium zevenboomii Head, 1997 differs by its smooth and undifferentiated pedium and the absence of distinct perforations of variable size and shape in the periblast. Furthermore, the separation between endoblast and periblast of A. zevenboomii is slightly higher (2.9 (4.1) 5.7 μm). Ataxiodinium choane REID, 1974 differs by a much larger cavation and fewer attachments of the periblast to the endoblast. Ataxiodinium confusum Versteegh and Zevenboom, 1995 is almost circumcavate in dorso-ventral view.
Holotype: Louwye, 2001, fig.3, nos.1-4.
Occurrence: Lower - Middle Miocene (Kiel Sands, Antwerpen Sands and Zonderschot Sands of the Berchem Formation) of northern Belgium as Tectatodinium sp. 1 (Louwye in press, Louwye et al. 2000); Middle - Late Miocene of the Norwegian Sea as Tectatodinium sp. 4 in Manum et al. (1989).
Age: Early-Mid Miocene.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Louwye, 2001]:
Diagnosis:
Small to intermediate, cavate cyst with an ellipsoid ambitus. The endoblast is formed by a solid pedium ornamented with low muri which form an incomplete microreticulum with irregular lumina. The periblast is a variably perforate tegillum which is randomly attached to the endoblast through irregular funnel shaped invaginations. The size and shape of the thin-walled periblast perforations are extremely variable in each specimen.
The archeopyle is formed by the release of the third precingular plate. The operculum is free.
Description:
The thickness of the solid pedium with muri is less than 0.3 μm. The microreticulate ornamentation formed by the low muri of the endoblast is difficult to discern under light microscopy. The number of attachments of the periblast to the endoblast is highly variable and appears random. The separation between endoblast and periblast is 4 μm at maximum. The circular to irregular ellipsoidal perforations of the periblast vary from less than 0.2 μm to maximum 5 μm.
The precingular archeopyle (type P) has smooth margins and straight angles; it is the only indication of a tabulation as no accessory sutures were observed.
Dimensions:
Holotype: length periblast 46 μm, equatorial width periblast 34 μm, average separation between endoblast and periblast: 3 μm.
Range: length periblast: 36 (43) 52 μm, equatorial width periblast: 28 (35) 42 μm, mean separation between periblast and endoblast: 2.9 μm. Number of specimens measured: 11.
Affinities/Comparison:
Ataxiodinium zevenboomii Head, 1997 differs by its smooth and undifferentiated pedium and the absence of distinct perforations of variable size and shape in the periblast. Furthermore, the separation between endoblast and periblast of A. zevenboomii is slightly higher (2.9 (4.1) 5.7 μm). Ataxiodinium choane REID, 1974 differs by a much larger cavation and fewer attachments of the periblast to the endoblast. Ataxiodinium confusum Versteegh and Zevenboom, 1995 is almost circumcavate in dorso-ventral view.