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Pseudoceratium solocispinum
From Fensome et al., 2019:
Pseudoceratium solocispinum (Davey, 1974, p.68, pl.9, fig.6) Harding, 1990b, p.19. Emendation: Harding, 1990b, p.19, as Pseudoceratium solocispinum. Holotype: Davey, 1974, pl.9, fig.6; Fensome et al., 2019a, fig.19L. Originally Pseudoceratium pelliferum var. solocispinum, subsequently Pseudoceratium pelliferum subsp. solocispinum, thirdly (and now) Pseudoceratium solocispinum. Age: middle–late Barremian.
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Original diagnosis: Davey, 1974, p. 68: Pseudoceratium pelliferum var. solocispinium
A variety of P. pelliferum processing a relatively broad central body, short lateral, apical and antapical horns coarse of ornamentation. The latter consists of spines of variable size and morphology; they may be joined distally or medially and are typicually truncated distally. The tabulation is sometimes marked by bands devoid of spines. The cingulum may be entirely barren of processes. An apical archaeopyle, with indications along the precingular plate boundaries, is usually present. The operculum rarely remains in position.
Original description: Davey, 1974, p. 68: Pseudoceratium pelliferum var. solocispinium
The surual bands are most noticeable between the pre- and postcingular plates. However, it was not possible to determine the tabulation formula. The horns on one specimenare reduced to elongations of the central body. Similar forms are known to occur in the Aptian. A second group of forms, also occurring in the Aptian and probably derived from P. pelliferum, possess broad, rounded horns.
Emended diagnosis: Harding, 1990, p. 19
Shape: Ambitus typically ceratioid with broad main body (L:W ratio 3:2). Hypocyst and epicyst approximately equal in length. Short, equidimensional horns in apical, postcingular and antapical positions. Pronounced dorso-ventral compression. Greatest width immediately post-paracingulum.
Phragma: Autophragm ca.1-2 Ám thick. Microrugulate surface from which arise processes of varying shape. Generally processes taper from the base distally and flare at the distal extremity, rod-like or flattened in crosssection. Processes may be distally antleriform and anastomose in mid-length and rarely be joined by trabeculae. They are reduced or absent from horn extremities.
Paratabulation: Corniform gonyaulacoid. Paratabulation as indicated by intratabular apteate processes: 4", 6", ?6c, 6""", 1"""", 1p, xs. Iu may be incorporated in parasulcus and indicated by two processes). Y contacts parasulcus.
Archaeopyle: Type (4A) involving the four apicals as a simple, free opercular piece. Archaeopyle suture zigzag, sulcal notch offset.
Paracingulum: Poorly developed, more obvious on dorsal surface where anterior and posterior parasutures are delineated. fi larger than rest of series.
Parasulcus: Broad lanceolate area of reduced sculpture.
Dimensions: Length - less operculum (85) 73 (66) Ám. Width (62) 58 (48) Ám. Length - plus operculum (130) 122.6 (108) Ám. Specimens = 26 (11).
Affinities:
Harding, 1990, p. 19: The elevation of this form to species level from subspecies level is justified by its distinct morphology. The short horns and the pronounced, robust nature of the processes set this form apart from Pseudoceratium pelliferum sensu stricto. In addition, this form is smaller and occurs stratigraphically later than P. pelliferum.
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Comments Fensome et al., 2019a:
This species was originally described as a variety of Pseudoceratium pelliferum. Davey (1974) did not clearly say how the variety differed from Pseudoceratium pelliferum var. pelliferum (and thus how Pseudoceratium solicispinum differs from Pseudoceratium pelliferum), but the epithet that he chose is partly based on the Latin solox, for coarse or rough. Certainly, the spines of Pseudoceratium solicispinum are longer than those of Pseudoceratium pelliferum. Harding (1990) raised this taxon to specific rank and provided an emended diagnosis, although he did not specifically state what his revised concept entailed. He provided some interesting SEMs, purportedly of Pseudoceratium pelliferum (his pl. 1, figs 7–8) and Pseudoceratium solocispinum (his pl. 1, figs 9–11) showing crispate (“curly”) elements, somewhat more pronounced in the latter species. It is not easy to relate the SEMs of Harding (1990) with the original light micrograph of the holotype of Pseudoceratium solocispinum.
Stratigraphical occurrence. The type material is from the middle and upper Barremian of northeastern England. However, Costa & Davey (1992) reported that this species is confined to the late Barremian.
Pseudoceratium solocispinum (Davey, 1974, p.68, pl.9, fig.6) Harding, 1990b, p.19. Emendation: Harding, 1990b, p.19, as Pseudoceratium solocispinum. Holotype: Davey, 1974, pl.9, fig.6; Fensome et al., 2019a, fig.19L. Originally Pseudoceratium pelliferum var. solocispinum, subsequently Pseudoceratium pelliferum subsp. solocispinum, thirdly (and now) Pseudoceratium solocispinum. Age: middle–late Barremian.
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Original diagnosis: Davey, 1974, p. 68: Pseudoceratium pelliferum var. solocispinium
A variety of P. pelliferum processing a relatively broad central body, short lateral, apical and antapical horns coarse of ornamentation. The latter consists of spines of variable size and morphology; they may be joined distally or medially and are typicually truncated distally. The tabulation is sometimes marked by bands devoid of spines. The cingulum may be entirely barren of processes. An apical archaeopyle, with indications along the precingular plate boundaries, is usually present. The operculum rarely remains in position.
Original description: Davey, 1974, p. 68: Pseudoceratium pelliferum var. solocispinium
The surual bands are most noticeable between the pre- and postcingular plates. However, it was not possible to determine the tabulation formula. The horns on one specimenare reduced to elongations of the central body. Similar forms are known to occur in the Aptian. A second group of forms, also occurring in the Aptian and probably derived from P. pelliferum, possess broad, rounded horns.
Emended diagnosis: Harding, 1990, p. 19
Shape: Ambitus typically ceratioid with broad main body (L:W ratio 3:2). Hypocyst and epicyst approximately equal in length. Short, equidimensional horns in apical, postcingular and antapical positions. Pronounced dorso-ventral compression. Greatest width immediately post-paracingulum.
Phragma: Autophragm ca.1-2 Ám thick. Microrugulate surface from which arise processes of varying shape. Generally processes taper from the base distally and flare at the distal extremity, rod-like or flattened in crosssection. Processes may be distally antleriform and anastomose in mid-length and rarely be joined by trabeculae. They are reduced or absent from horn extremities.
Paratabulation: Corniform gonyaulacoid. Paratabulation as indicated by intratabular apteate processes: 4", 6", ?6c, 6""", 1"""", 1p, xs. Iu may be incorporated in parasulcus and indicated by two processes). Y contacts parasulcus.
Archaeopyle: Type (4A) involving the four apicals as a simple, free opercular piece. Archaeopyle suture zigzag, sulcal notch offset.
Paracingulum: Poorly developed, more obvious on dorsal surface where anterior and posterior parasutures are delineated. fi larger than rest of series.
Parasulcus: Broad lanceolate area of reduced sculpture.
Dimensions: Length - less operculum (85) 73 (66) Ám. Width (62) 58 (48) Ám. Length - plus operculum (130) 122.6 (108) Ám. Specimens = 26 (11).
Affinities:
Harding, 1990, p. 19: The elevation of this form to species level from subspecies level is justified by its distinct morphology. The short horns and the pronounced, robust nature of the processes set this form apart from Pseudoceratium pelliferum sensu stricto. In addition, this form is smaller and occurs stratigraphically later than P. pelliferum.
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Comments Fensome et al., 2019a:
This species was originally described as a variety of Pseudoceratium pelliferum. Davey (1974) did not clearly say how the variety differed from Pseudoceratium pelliferum var. pelliferum (and thus how Pseudoceratium solicispinum differs from Pseudoceratium pelliferum), but the epithet that he chose is partly based on the Latin solox, for coarse or rough. Certainly, the spines of Pseudoceratium solicispinum are longer than those of Pseudoceratium pelliferum. Harding (1990) raised this taxon to specific rank and provided an emended diagnosis, although he did not specifically state what his revised concept entailed. He provided some interesting SEMs, purportedly of Pseudoceratium pelliferum (his pl. 1, figs 7–8) and Pseudoceratium solocispinum (his pl. 1, figs 9–11) showing crispate (“curly”) elements, somewhat more pronounced in the latter species. It is not easy to relate the SEMs of Harding (1990) with the original light micrograph of the holotype of Pseudoceratium solocispinum.
Stratigraphical occurrence. The type material is from the middle and upper Barremian of northeastern England. However, Costa & Davey (1992) reported that this species is confined to the late Barremian.