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Pseudoceratium securigerum
Pseudoceratium securigerum (Davey and Verdier, 1974) Bint, 1986
Originally Aptea, subsequently (and now) Pseudoceratium.
Holotype: Davey and Verdier, 1974, pl.91, fig.3
Locus typicus: La BÚdoule, SE France
Stratum typicum: Early Aptian (Bedoulian)
Original description: Davey and Verdier, 1974, p. 642-643: Aptea securigera
Diagnosis: The cyst central body is dorso-ventrally flattened and rounded triangular in shape. The left side is strongly, but evenly, convex; the right epitractal and hypotractal sides are slightly convex to straight and meet at approximately right angles in the cingular region. The right hypotractal side often has a medial convexity. The apex and, to a lesser extent, the antapex are developed as protuberances of the central body and are rounded distally. The cyst surface bears numerous short, flattened, solid processes which are concentrated in the circumferential region. A more or less circular area in the centre of the ventral and dorsal surfaces is devoid of, or possesses only rare, processes. The processes are of variable shape but are typically discrete, expanding both distally and proximally, and are flat-topped distally; their
length is more than twice as their medial width. The processes are longer and more variable at the cyst apices. Very rarely the cingulum and other tabulation is marked by narrow bands devoid of processes. The archaeopyle is apical and possesses a strongly zigzag margin. The operculum is usually detached. Dimensions: Central body length: 73-90 Ám; Central body width: 69-87 Ám; Central body length (operculum detached): 62-73 Ám; Height of processes: 2-10 Ám.
Description: The processes characteristically widen both distally and proximally.
Very rarely, narrow processes may bifurcate or trifurcate, or neighbouring processes may be linked medially by a crest. Rarely the bases of two or three neighbouring processes may be linked by a low ridge or thickening of the cyst wall. These thickenings tend to parallel the cyst sides, as do the crests in A. polymorpha. Besides the longer processes at the cyst apices, slightly longer ones may also be present on the left side in the cingular region and on the
convexity or bulge, if present, of the right hypotractal side. These longer processes were seen to be linked distally in one specimen.
Affinities: Davey and Verdier, 1974, p. 643: Aptea securigerum
Aptea securigera is differentiatedl from Aptea polymorpha by the absence of well-developed crests and from Aptea eisenacki (Davey 1969) by the presence of numerous stout processes. Aptea attadalica (Cookson and Eisenack 1962), from the Apto-?Albian of Australia, is most similar but possesses a wide distinctive cingulum and usually a ventral furrow.
Bint, 1986, p.146: Specimens of P. securigerum with moderately dense ornament are similar to P. retusum which differs in having a more dense ornament of longer, often bifurcate processes which may be linked basally and/or distally forming a partial ectophragm. Specimens of P. securigerum with very sparse, low ornament are similar to P. expolitum which has a smooth, scabrate, or microreticulate wall and may have long horns. Finally, specimens of P. securigerum with considerable process linkage in a linear arrangement are similar to P. eisenackii which is ornamented with a network of low crests.
Originally Aptea, subsequently (and now) Pseudoceratium.
Holotype: Davey and Verdier, 1974, pl.91, fig.3
Locus typicus: La BÚdoule, SE France
Stratum typicum: Early Aptian (Bedoulian)
Original description: Davey and Verdier, 1974, p. 642-643: Aptea securigera
Diagnosis: The cyst central body is dorso-ventrally flattened and rounded triangular in shape. The left side is strongly, but evenly, convex; the right epitractal and hypotractal sides are slightly convex to straight and meet at approximately right angles in the cingular region. The right hypotractal side often has a medial convexity. The apex and, to a lesser extent, the antapex are developed as protuberances of the central body and are rounded distally. The cyst surface bears numerous short, flattened, solid processes which are concentrated in the circumferential region. A more or less circular area in the centre of the ventral and dorsal surfaces is devoid of, or possesses only rare, processes. The processes are of variable shape but are typically discrete, expanding both distally and proximally, and are flat-topped distally; their
length is more than twice as their medial width. The processes are longer and more variable at the cyst apices. Very rarely the cingulum and other tabulation is marked by narrow bands devoid of processes. The archaeopyle is apical and possesses a strongly zigzag margin. The operculum is usually detached. Dimensions: Central body length: 73-90 Ám; Central body width: 69-87 Ám; Central body length (operculum detached): 62-73 Ám; Height of processes: 2-10 Ám.
Description: The processes characteristically widen both distally and proximally.
Very rarely, narrow processes may bifurcate or trifurcate, or neighbouring processes may be linked medially by a crest. Rarely the bases of two or three neighbouring processes may be linked by a low ridge or thickening of the cyst wall. These thickenings tend to parallel the cyst sides, as do the crests in A. polymorpha. Besides the longer processes at the cyst apices, slightly longer ones may also be present on the left side in the cingular region and on the
convexity or bulge, if present, of the right hypotractal side. These longer processes were seen to be linked distally in one specimen.
Affinities: Davey and Verdier, 1974, p. 643: Aptea securigerum
Aptea securigera is differentiatedl from Aptea polymorpha by the absence of well-developed crests and from Aptea eisenacki (Davey 1969) by the presence of numerous stout processes. Aptea attadalica (Cookson and Eisenack 1962), from the Apto-?Albian of Australia, is most similar but possesses a wide distinctive cingulum and usually a ventral furrow.
Bint, 1986, p.146: Specimens of P. securigerum with moderately dense ornament are similar to P. retusum which differs in having a more dense ornament of longer, often bifurcate processes which may be linked basally and/or distally forming a partial ectophragm. Specimens of P. securigerum with very sparse, low ornament are similar to P. expolitum which has a smooth, scabrate, or microreticulate wall and may have long horns. Finally, specimens of P. securigerum with considerable process linkage in a linear arrangement are similar to P. eisenackii which is ornamented with a network of low crests.