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Acanthaulax senta
From Fensome et al., 2019:
Acanthaulax senta, Drugg, 1978, p.62, pl.3, fig.13; pl.4, figs.1–3.
Holotype: Drugg, 1978, pl.4, fig.2; Jan du Chêne et al., 1986a, pl.4, figs.1–2.
Taxonomic senior synonym: Gonyaulacysta (now Trichodinium) scarburghensis, according to Berger (1986, p.343) and Kunz (1990, p.14).
Age: Oxfordian.
Locus typicus: Oxford Clay at Red Cliff, England.
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Original description: [Drugg, 1978, p. 62]:
Description:
Cyst relatively large and bearing a precingular archeopyle. The ornamentation is somewhat variable but distinctive. It consists of spines from 2 to 4 µm in length. The tips may be pointed, blunt, or furcate. Trabeculae often connect the distal ends together. On some specimens these trabeculae or distal connections form what almost amounts to an open mesh outer layer. The autophragm is smooth and unornamented except for occasional low ridge-like interconnections between the bases of the spines. The autophragm is about 1 µm in thickness. A paracingulum is usually clearly expressed by the ornamentation and sometimes there are additional hints of paratabulation given by linear alignments of spines. The paratabulation is presumably gonyaulacid. An apical horn ranging in length from 14 to 24 µm is formed by elongate anastomosing fibers or "processes". At times the autophragm extends upwards into a low rounded horn or bump but more commonly takes no part in horn formation. There is no antapical horn although the ornamentation in that area is sometimes longer and more dense.
Dimensions:
The total length ranges from 99 to 140 µm and the width ranges from 67 to 105 µm.
Affinities:
This species differs primarily from the three previously described species of Acanthaulax (A. downiei, A. paliuros, A. venusta in possessing a prominent apical horn or tuft of spines. The shape is also more elongate. This new species is probably conspecific with Acanthaulax sp. 2 of Johnson and Hills, 1973.
Acanthaulax senta, Drugg, 1978, p.62, pl.3, fig.13; pl.4, figs.1–3.
Holotype: Drugg, 1978, pl.4, fig.2; Jan du Chêne et al., 1986a, pl.4, figs.1–2.
Taxonomic senior synonym: Gonyaulacysta (now Trichodinium) scarburghensis, according to Berger (1986, p.343) and Kunz (1990, p.14).
Age: Oxfordian.
Locus typicus: Oxford Clay at Red Cliff, England.
---------------------------------------------------------------------------------------------------
Original description: [Drugg, 1978, p. 62]:
Description:
Cyst relatively large and bearing a precingular archeopyle. The ornamentation is somewhat variable but distinctive. It consists of spines from 2 to 4 µm in length. The tips may be pointed, blunt, or furcate. Trabeculae often connect the distal ends together. On some specimens these trabeculae or distal connections form what almost amounts to an open mesh outer layer. The autophragm is smooth and unornamented except for occasional low ridge-like interconnections between the bases of the spines. The autophragm is about 1 µm in thickness. A paracingulum is usually clearly expressed by the ornamentation and sometimes there are additional hints of paratabulation given by linear alignments of spines. The paratabulation is presumably gonyaulacid. An apical horn ranging in length from 14 to 24 µm is formed by elongate anastomosing fibers or "processes". At times the autophragm extends upwards into a low rounded horn or bump but more commonly takes no part in horn formation. There is no antapical horn although the ornamentation in that area is sometimes longer and more dense.
Dimensions:
The total length ranges from 99 to 140 µm and the width ranges from 67 to 105 µm.
Affinities:
This species differs primarily from the three previously described species of Acanthaulax (A. downiei, A. paliuros, A. venusta in possessing a prominent apical horn or tuft of spines. The shape is also more elongate. This new species is probably conspecific with Acanthaulax sp. 2 of Johnson and Hills, 1973.