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Heslertonia senecta
Heslertonia senecta Harding, 1990b, p.27, pl.8, figs.1–11; text-fig.10 ex Harding in Williams et al. 1998, p.265.
This name was not validly published in Harding (1990b) since the lodgement of the holotype was not specified (I.C.N. Article 40.7).
Holotype: Harding, 1990b, pl.8, fig.1.
Locus typicus: O. Gott, Lower Saxony, Germany
Stratum typicum: Late Barremian
Original diagnosis: Harding, 1990, p. 27
Shape: Central body spheroidal to prolate ovoidal. Ambitus modified by the high parasutural septa into a more polygonal shape. Greatest width across paracingulum. Hypocyst marginally longer than epicyst. accentuated by the greater development of septa. No dorso-ventral compression.
Phragma: Periphragm extremely thin (1 µm), closely adpressed to the endophragm in intratabular areas where it is wrinkled, forming a characteristic rugulate sculpture (rugulae ca. 0.25 µm wide). Septa formed by outfolds if the periphragm (causing suturocavation), thus septa are two-layered and usually distally entire (if open the edges are denticulate). Septa covered in parallel, radiating striae or corrugations. Septa may exhibit circular claustra which may develop into septal fenestrations at the base of the septum. Endophragm spheroidal to ovoidal, 1 µm thick, surface sculpture not observed.
Paratabulation: Sexiform L-type gonyaulacoid. Paratabulation formula: 4", 6", 6c, 6""", 1"""", 1p, 5s. Sulcal parasutures partially supressed.
Archaeopyle: Type Ea, simple reduced operculum, adnate via ai, but may be removed mechanically.
Paracingulum: Very prominent double layered septum forms a paracingular "tunnel" which is perforated in intratabular areas, the edges of the perforations being denticulate.
Parasulcus: Rarely observed, parasutures suppressed so that septa reduced or replaced by denticles.
Dimensions: Length (70) 61.6 (53) µm. Width (62) 52.6 (45) µm. Specimens = 13 (11).
Affinities:
Harding, 1990, p. 27: A late Barremian species of the genus which differs from the other members of the genus by its rugulate sculpture (H. heslertonensls the other Barremian species of the genus does not have a rugulate periphragm, see Plate 8, Fig. 12). H. teichophera and H. striata, Jurassic and late Cretaceous species respectively, both have striate septa but lack the conspicuously rugulate intratabular areas. The latter two species are also stated to possess Type P4 archaeopyles, but this is uncertain.
This name was not validly published in Harding (1990b) since the lodgement of the holotype was not specified (I.C.N. Article 40.7).
Holotype: Harding, 1990b, pl.8, fig.1.
Locus typicus: O. Gott, Lower Saxony, Germany
Stratum typicum: Late Barremian
Original diagnosis: Harding, 1990, p. 27
Shape: Central body spheroidal to prolate ovoidal. Ambitus modified by the high parasutural septa into a more polygonal shape. Greatest width across paracingulum. Hypocyst marginally longer than epicyst. accentuated by the greater development of septa. No dorso-ventral compression.
Phragma: Periphragm extremely thin (1 µm), closely adpressed to the endophragm in intratabular areas where it is wrinkled, forming a characteristic rugulate sculpture (rugulae ca. 0.25 µm wide). Septa formed by outfolds if the periphragm (causing suturocavation), thus septa are two-layered and usually distally entire (if open the edges are denticulate). Septa covered in parallel, radiating striae or corrugations. Septa may exhibit circular claustra which may develop into septal fenestrations at the base of the septum. Endophragm spheroidal to ovoidal, 1 µm thick, surface sculpture not observed.
Paratabulation: Sexiform L-type gonyaulacoid. Paratabulation formula: 4", 6", 6c, 6""", 1"""", 1p, 5s. Sulcal parasutures partially supressed.
Archaeopyle: Type Ea, simple reduced operculum, adnate via ai, but may be removed mechanically.
Paracingulum: Very prominent double layered septum forms a paracingular "tunnel" which is perforated in intratabular areas, the edges of the perforations being denticulate.
Parasulcus: Rarely observed, parasutures suppressed so that septa reduced or replaced by denticles.
Dimensions: Length (70) 61.6 (53) µm. Width (62) 52.6 (45) µm. Specimens = 13 (11).
Affinities:
Harding, 1990, p. 27: A late Barremian species of the genus which differs from the other members of the genus by its rugulate sculpture (H. heslertonensls the other Barremian species of the genus does not have a rugulate periphragm, see Plate 8, Fig. 12). H. teichophera and H. striata, Jurassic and late Cretaceous species respectively, both have striate septa but lack the conspicuously rugulate intratabular areas. The latter two species are also stated to possess Type P4 archaeopyles, but this is uncertain.