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Biorbifera barremiana
From Fensome et al., 2019:
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Origional description Duxbury, 2019:
Holotype: Plate 3, Figure 19.
Type Locality: Heslerton No. 2 at 26.00 m (core chip), late
Barremian age. Holotype: E.F. N45.4.
Derivation of Name: From “Barremian” - in reference to the observed range of this species.
Diagnosis: A small, spheroidal to ovoidal species with a wide cingulum and broadly rounded poles. The cyst surface bears dense granules or coni associated with relatively widely-spaced, short, broadly-tapering, acuminate spines which are occasionally linked by slender trabeculae close to their contact with the main body. The cingulum is devoid of spines. The hypocyst is significantly longer than the epicyst. Archeopyle epicystal, operculum attached.
Dimensions: Holotype: Length - 30 μm. Width - 25 μm.
Overall: 30 (27) 25 μm × 25(24) 23 μm.
Specimens Measured: 3.
Remarks: This very small species is similar to Biorbifera johnewingii Habib 1972 in the absence of apical or antapical projections, in having a cover of spines and in displaying an epicystal archeopyle. It is also similar in having a denser cover of much shorter ornament, not recognised by Habib (op. cit.) but clearly shown by Below (1987, Plate 27, Figures 1-7, 13, 14, 19, 20). Below (op. cit.) also showed that spines can be absent from the cingular area of B. johnewingii, just as in B. barremiana n. sp.
In contrast to B. johnewingii, B. barremiana has a much more rounded outline, with little or no indentation of the cingulum and significantly fewer spines. Also, Habib (1976, p. 384) stated that, “In most cases, the distribution of the spinate processes is nontabular, with fewer processes present on the cingulum. In others, however, cyst tabulation is expressed by peritabular and intratabular arrangement of the processes, outlining plates of the precingular, cingular, postcingular, and antapical series”. No clear indication of tabulation has been observed in B. barremiana, possibly because of the less dense spine cover. A further feature of B. barremiana which was not demonstrated in B. johnewingii either by Habib (1972, 1976) or Below (1987) is the lateral connection of some spines by slender “bars” a short distance from the cyst surface. This feature is seen on the epicyst of the holotype of B. barremiana (Plate 3, Figure 19).
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Origional description Duxbury, 2019:
Holotype: Plate 3, Figure 19.
Type Locality: Heslerton No. 2 at 26.00 m (core chip), late
Barremian age. Holotype: E.F. N45.4.
Derivation of Name: From “Barremian” - in reference to the observed range of this species.
Diagnosis: A small, spheroidal to ovoidal species with a wide cingulum and broadly rounded poles. The cyst surface bears dense granules or coni associated with relatively widely-spaced, short, broadly-tapering, acuminate spines which are occasionally linked by slender trabeculae close to their contact with the main body. The cingulum is devoid of spines. The hypocyst is significantly longer than the epicyst. Archeopyle epicystal, operculum attached.
Dimensions: Holotype: Length - 30 μm. Width - 25 μm.
Overall: 30 (27) 25 μm × 25(24) 23 μm.
Specimens Measured: 3.
Remarks: This very small species is similar to Biorbifera johnewingii Habib 1972 in the absence of apical or antapical projections, in having a cover of spines and in displaying an epicystal archeopyle. It is also similar in having a denser cover of much shorter ornament, not recognised by Habib (op. cit.) but clearly shown by Below (1987, Plate 27, Figures 1-7, 13, 14, 19, 20). Below (op. cit.) also showed that spines can be absent from the cingular area of B. johnewingii, just as in B. barremiana n. sp.
In contrast to B. johnewingii, B. barremiana has a much more rounded outline, with little or no indentation of the cingulum and significantly fewer spines. Also, Habib (1976, p. 384) stated that, “In most cases, the distribution of the spinate processes is nontabular, with fewer processes present on the cingulum. In others, however, cyst tabulation is expressed by peritabular and intratabular arrangement of the processes, outlining plates of the precingular, cingular, postcingular, and antapical series”. No clear indication of tabulation has been observed in B. barremiana, possibly because of the less dense spine cover. A further feature of B. barremiana which was not demonstrated in B. johnewingii either by Habib (1972, 1976) or Below (1987) is the lateral connection of some spines by slender “bars” a short distance from the cyst surface. This feature is seen on the epicyst of the holotype of B. barremiana (Plate 3, Figure 19).