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Endoscrinium hauterivianum
From Fensome et al., 2019:
Endoscrinium hauterivianum (Duxbury, 2001, p.113–114, fig.13, nos.1–3) Riding and Fensome, 2002, p.21. Holotype: Duxbury, 2001, fig.13, no.2. Originally Scriniodinium, subsequently (and now) Endoscrinium. Age: early–early late Hauterivian.
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Original description (Duxbury, 2001):
Scriniodinium hauterivianum n. sp.
Holotype: Figure 13.2.
Type Locality: Well 14/18b-12 at 8451.0 ft (sidewall core), Early Hauterivian, E.F. F39.0.
Derivation of Name: From the Hauterivian - this species is restricted to that Stage.
Diagnosis: A spheroidal species of Scriniodinium with a smooth to very finely granular, ovoidal endocyst, bearing a very low apical protrusion. The delicate, smooth pericyst is separated from the endocyst to varying degrees, although the endocyst consistently fills much of the pericyst. The maximum separation observed is in the ventral and hypocystal areas. A short, hollow, sharply-tapering but blunt-ended apical horn is consistently observed, formed entirely by the pericyst. The archeopyle is single paraplate precingular (3").
Dimensions: Holotype: 90 x 79 μm
Overall: 95 (91) 71 x 85 (77) 71 μm
Specimens Measured - 15.
Comments: Scriniodinium hauterivianum n. sp. is a distinctive species, although it is similar in some respects to Scriniodinium barremianum DUXBURY n. sp., Apteodinium spongiosum McINTYRE & BRIDEAUX, 1980 and Athigmatocysta glabra DUXBURY, 1977.
It differs from S. barremianum in being significantly more cavate, and in possessing a sharply-tapering apical horn without perforations. In contrast, S. barremianum has minimal cavation and a distally perforate apical horn.
The surface of Apteodinium spongiosum McINTYRE & BRIDEAUX (op. cit.) displays a complex arrangement of sponge-like thickenings, in marked
contrast with the smooth surface of Scriniodinium hauterivianum DUXBURY n. sp. Also, there appears to be little or no wall separation in A. spongiosum, except at the apex, whereas a distinct cavation is present in S. hauterivianum. No paratabulation was observed in S. hauterivianum, and this contrasts with the complete paratabulation displayed by Athigmatocysta glabra DUXBURY, 1977. Also, the cavation of the last species is significantly better-developed than that of the former, and its apical projecion is significantly smaller.
This species is essentially an Early Hauterivian form, although it can range into the base of the Late Hauterivian.
Endoscrinium hauterivianum (Duxbury, 2001, p.113–114, fig.13, nos.1–3) Riding and Fensome, 2002, p.21. Holotype: Duxbury, 2001, fig.13, no.2. Originally Scriniodinium, subsequently (and now) Endoscrinium. Age: early–early late Hauterivian.
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Original description (Duxbury, 2001):
Scriniodinium hauterivianum n. sp.
Holotype: Figure 13.2.
Type Locality: Well 14/18b-12 at 8451.0 ft (sidewall core), Early Hauterivian, E.F. F39.0.
Derivation of Name: From the Hauterivian - this species is restricted to that Stage.
Diagnosis: A spheroidal species of Scriniodinium with a smooth to very finely granular, ovoidal endocyst, bearing a very low apical protrusion. The delicate, smooth pericyst is separated from the endocyst to varying degrees, although the endocyst consistently fills much of the pericyst. The maximum separation observed is in the ventral and hypocystal areas. A short, hollow, sharply-tapering but blunt-ended apical horn is consistently observed, formed entirely by the pericyst. The archeopyle is single paraplate precingular (3").
Dimensions: Holotype: 90 x 79 μm
Overall: 95 (91) 71 x 85 (77) 71 μm
Specimens Measured - 15.
Comments: Scriniodinium hauterivianum n. sp. is a distinctive species, although it is similar in some respects to Scriniodinium barremianum DUXBURY n. sp., Apteodinium spongiosum McINTYRE & BRIDEAUX, 1980 and Athigmatocysta glabra DUXBURY, 1977.
It differs from S. barremianum in being significantly more cavate, and in possessing a sharply-tapering apical horn without perforations. In contrast, S. barremianum has minimal cavation and a distally perforate apical horn.
The surface of Apteodinium spongiosum McINTYRE & BRIDEAUX (op. cit.) displays a complex arrangement of sponge-like thickenings, in marked
contrast with the smooth surface of Scriniodinium hauterivianum DUXBURY n. sp. Also, there appears to be little or no wall separation in A. spongiosum, except at the apex, whereas a distinct cavation is present in S. hauterivianum. No paratabulation was observed in S. hauterivianum, and this contrasts with the complete paratabulation displayed by Athigmatocysta glabra DUXBURY, 1977. Also, the cavation of the last species is significantly better-developed than that of the former, and its apical projecion is significantly smaller.
This species is essentially an Early Hauterivian form, although it can range into the base of the Late Hauterivian.