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Wilsonidium tabulatum
From Fensome et al., 2019:
Wilsonidium tabulatum (Wilson, 1967) Lentin and Williams, 1976
Originally Wetzeliella, subsequently (and now) Wilsonidium.
Holotype: Wilson, 1967, fig.4-6
Locus typicus: Rakis Table, Omaru, New Zealand
Stratum typicum: Late Eocene
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Original description: Wilson, 1967, p.473: Wetzeliella tabulata
Periphragm outline pentagonal, bilaterally asymmetric, with well developed horns at each angle. Apical, lateral and right antapical horns all approximately equal in size; left antapical horn always shorter although still prominent. Polar horns tapered, pointed; lateral horns have a well defined notch at their extremities denoting the position of a transverse girdle. Periphragm divided into clearly defined fields by rows of slender non-tapering solid spines (l=2-8 µm) which are occasionally united at their bases by a low ridge. Tabulation typical of genus (Fig.2). Margin between horns concave, usually irregularly spinose, occasionally smooth. Capsule outline varies from circular to sub-angular. Archeopyle corresponds to 2a plate, shape square to rectangular; operculum often located within capsule. Transverse girdle clearly defined by double row of spines, slightly laevorotatory.
Affinities:
Wilson, 1967, p.474: Wetzeliella tabulata
Wetz. (W.) tabulata is a very distinctive species with a well defined reflected tabulation. lt bears some similarity to W. (W.) Iineidentata Defl. and Cooks. but differs considerably in periphragm outline and in the nature of the spines.
The processes (i.e., the spines) of this species are not equivalent to the simulate complexes recognised by Williams and Downie (1966) in Wetzeliella species from the London Clay and instead correspond to the sutures between adjacent plates.
The operculum of this species, as with other species of Wetzeliella. consists of two layers corresponding to the periphragm and capsule. These may be joined but are usually separate. It is mostly only the inner layer which is found within the capsule.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 -
Wilsonidium tabulatum (Wilson, 1967c) Lentin and Williams, 1976. From Wilson (1967c, p.473), has a pentagonal pericyst, with the left antapical horn being slightly longer than the right. Cingular horns notched on margins showing position of cingulum. Pericyst divided into fields by rows of slender, non-tapering solid spines (length 2-8 Fm), which are occasionally united at their bases by low ridges. Well developed ambital pericoel. Archeopyle hyperepeliform. Wilsonidium tabulatum differs from Wilsonidium lineidentatum in the periphragm outline and the nature of the spines. Size: length pericyst 127-171 µm, width 113-156 µm, endocyst 89 x 84, length of apical horn 19-39 µm, length of left antapical horn 11-19 µm, length of right antapical horn 19-36 µm, length of lateral horns 19-27 µm.
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Wilsonidium tabulatum (Wilson, 1967) Lentin and Williams, 1976
Originally Wetzeliella, subsequently (and now) Wilsonidium.
Holotype: Wilson, 1967, fig.4-6
Locus typicus: Rakis Table, Omaru, New Zealand
Stratum typicum: Late Eocene
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Original description: Wilson, 1967, p.473: Wetzeliella tabulata
Periphragm outline pentagonal, bilaterally asymmetric, with well developed horns at each angle. Apical, lateral and right antapical horns all approximately equal in size; left antapical horn always shorter although still prominent. Polar horns tapered, pointed; lateral horns have a well defined notch at their extremities denoting the position of a transverse girdle. Periphragm divided into clearly defined fields by rows of slender non-tapering solid spines (l=2-8 µm) which are occasionally united at their bases by a low ridge. Tabulation typical of genus (Fig.2). Margin between horns concave, usually irregularly spinose, occasionally smooth. Capsule outline varies from circular to sub-angular. Archeopyle corresponds to 2a plate, shape square to rectangular; operculum often located within capsule. Transverse girdle clearly defined by double row of spines, slightly laevorotatory.
Affinities:
Wilson, 1967, p.474: Wetzeliella tabulata
Wetz. (W.) tabulata is a very distinctive species with a well defined reflected tabulation. lt bears some similarity to W. (W.) Iineidentata Defl. and Cooks. but differs considerably in periphragm outline and in the nature of the spines.
The processes (i.e., the spines) of this species are not equivalent to the simulate complexes recognised by Williams and Downie (1966) in Wetzeliella species from the London Clay and instead correspond to the sutures between adjacent plates.
The operculum of this species, as with other species of Wetzeliella. consists of two layers corresponding to the periphragm and capsule. These may be joined but are usually separate. It is mostly only the inner layer which is found within the capsule.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 -
Wilsonidium tabulatum (Wilson, 1967c) Lentin and Williams, 1976. From Wilson (1967c, p.473), has a pentagonal pericyst, with the left antapical horn being slightly longer than the right. Cingular horns notched on margins showing position of cingulum. Pericyst divided into fields by rows of slender, non-tapering solid spines (length 2-8 Fm), which are occasionally united at their bases by low ridges. Well developed ambital pericoel. Archeopyle hyperepeliform. Wilsonidium tabulatum differs from Wilsonidium lineidentatum in the periphragm outline and the nature of the spines. Size: length pericyst 127-171 µm, width 113-156 µm, endocyst 89 x 84, length of apical horn 19-39 µm, length of left antapical horn 11-19 µm, length of right antapical horn 19-36 µm, length of lateral horns 19-27 µm.
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