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Endoscrinium acroferum
From Fensome et al., 2019:
Endoscrinium acroferum (Prauss, 1989, p.45–46, pl.9, figs.1–2, pl.14, figs.17–22; text-fig.21) Riding and Fensome, 2002, p.21. Originally Scriniodinium, subsequently (and now) Endoscrinium. Holotype: Prauss, 1989, pl.14, figs.19–21; textfig. 21. Age: late Bathonian–late Callovian.
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Original description: [Prauss, 1989] (translated from German):
Scriniodinium acroferum n. sp.
Derivatio nominis: akros (Greek) = pointed, top; ferre (Latin) = to carry, after the conical tapering of the apical region.
Holotype: 1b, 2. 4, Plate 14, Figs. 19-21.
Locus typicus: former brickworks Lechstedt/near Hildesheim.
Stratum typicum: O'Bathon, Bodsoni zone, mudstone, marly, dark gray, silty.
Description: Cyst habitus proximate/cavate. Ambitus ovoidal to ellipsoidal. Endoblast spheroidal to ellipsoidal. Wall composed of pedium and luxuria. Luxuria detached over most of the wall (except for the sulcal area) to the tectum. Endoblast scabrate, periblast psilate. The periblast forms a blunt-conical, slightly distinct horn apically, which is characteristic of this species. Area only on the periblast: cop, pop, cap, POR, 4', 6 Xc, 6", 1p, 1"", NRs. Area 1"" is very small and lies within the sulcal area. It is only visible at high resolution and is completely suppressed in some individuals. The two small anterior intercalary areas are located between areas 2', 3', 3" and 4". The porichnion (see EVITT 1985, p. 74) always lies on the triple point of cap/1/4'. Periarcheopyle precingular, 3". Perioperculum secat. Endarcheopyle Precingular, ?3 Endoperculum secat. The fins of the periblast are formed by very low sutures and/or folds, on which short, echinaceous structures sit at sometimes irregular intervals. These are generally more distinct and robust on the hypocyst.
Dimensions (Mean):
Endoblast (Ø): 66.1
Periblast: L: 90.8, W: 86.7
Apical horn: L: 6.9
Measured individuals: 5
Remarks: This sparsely but regularly occurring species differs from all previously described Scriniodinium species by the small anterior intercalary areas typical of gonyaulacoid forms, as well as the porichnion. The echinate ornaments of the finis and the blunt-conical apical structure are also typical distinguishing features. Endoscrinium bessebae BELOW 1981a differs from the species, in addition to the basic characteristics mentioned, in the type and distribution of the finate ornamentations, as well as in the bi-polyfurcate apical tip. E. campanula (GOCHT 1959) VOZZHENNIKOVA 1967 is usually only weakly to hypogeal and has no finate echinae.
Occurrence: O'Bathonium O'Callovium, hodsoni to athleta/lamberti zone.
Endoscrinium acroferum (Prauss, 1989, p.45–46, pl.9, figs.1–2, pl.14, figs.17–22; text-fig.21) Riding and Fensome, 2002, p.21. Originally Scriniodinium, subsequently (and now) Endoscrinium. Holotype: Prauss, 1989, pl.14, figs.19–21; textfig. 21. Age: late Bathonian–late Callovian.
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Original description: [Prauss, 1989] (translated from German):
Scriniodinium acroferum n. sp.
Derivatio nominis: akros (Greek) = pointed, top; ferre (Latin) = to carry, after the conical tapering of the apical region.
Holotype: 1b, 2. 4, Plate 14, Figs. 19-21.
Locus typicus: former brickworks Lechstedt/near Hildesheim.
Stratum typicum: O'Bathon, Bodsoni zone, mudstone, marly, dark gray, silty.
Description: Cyst habitus proximate/cavate. Ambitus ovoidal to ellipsoidal. Endoblast spheroidal to ellipsoidal. Wall composed of pedium and luxuria. Luxuria detached over most of the wall (except for the sulcal area) to the tectum. Endoblast scabrate, periblast psilate. The periblast forms a blunt-conical, slightly distinct horn apically, which is characteristic of this species. Area only on the periblast: cop, pop, cap, POR, 4', 6 Xc, 6", 1p, 1"", NRs. Area 1"" is very small and lies within the sulcal area. It is only visible at high resolution and is completely suppressed in some individuals. The two small anterior intercalary areas are located between areas 2', 3', 3" and 4". The porichnion (see EVITT 1985, p. 74) always lies on the triple point of cap/1/4'. Periarcheopyle precingular, 3". Perioperculum secat. Endarcheopyle Precingular, ?3 Endoperculum secat. The fins of the periblast are formed by very low sutures and/or folds, on which short, echinaceous structures sit at sometimes irregular intervals. These are generally more distinct and robust on the hypocyst.
Dimensions (Mean):
Endoblast (Ø): 66.1
Periblast: L: 90.8, W: 86.7
Apical horn: L: 6.9
Measured individuals: 5
Remarks: This sparsely but regularly occurring species differs from all previously described Scriniodinium species by the small anterior intercalary areas typical of gonyaulacoid forms, as well as the porichnion. The echinate ornaments of the finis and the blunt-conical apical structure are also typical distinguishing features. Endoscrinium bessebae BELOW 1981a differs from the species, in addition to the basic characteristics mentioned, in the type and distribution of the finate ornamentations, as well as in the bi-polyfurcate apical tip. E. campanula (GOCHT 1959) VOZZHENNIKOVA 1967 is usually only weakly to hypogeal and has no finate echinae.
Occurrence: O'Bathonium O'Callovium, hodsoni to athleta/lamberti zone.