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Prolixosphaeridium nanus
Prolixosphaeridium ?nanus (Wetzel, 1933b, p.43, pl.4, fig.23; text-fig.13 ex Lentin and Williams, 1985, p.322) Sarjeant, 1985b, p.145. Emendation: Sarjeant, 1985b, p.145, as Prolixosphaeridium nanus.
Originally Hystrichosphaera pilosa forma nanus (name not validly published), subsequently Sentusidinium pilosum? subsp. nanus, thirdly Prolixosphaeridium nanus, fourthly (and now) Prolixosphaeridium? nanus. Questionable assignment: Fauconnier and Monteil in Fauconnier and Masure (2004, p.462–463).
The name Hystrichosphaera pilosa forma nanus was not validly published in Wetzel (1933b) since the species combination Hystrichosphaera pilosa was not validly published.
Holotype: O. Wetzel, 1933, pl.4, fig.23; Sarjeant, 1986, pl.2, figs.6-7
Age: Late Cretaceous
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Prolixosphaeridium? cf. nanum (O. Wetzel, 1933) Sarjeant, 1985
Figured in Schioler et al.: Plate IV, 4
Description: Schioler et al. 1997, p. 87, 89
Small oval microgranulate phragm covered with 30-50 mainly solid and flexible simple processes.
Dimensions (in µm, 5 specimens measured): length, 30 (34) 38; width, 15 (19) 21; length of processes, 5-12.
Discussion: This taxon resembles P. nanum in general shape and in size, but differs in having mainly solid processes. It closely resembles specimens assigned to Prolixosphaeridium cf. nanum by Marheinecke (1992) and specimens assigned to Micrhystrium piliferum by Harker et al. (1990). These and the present taxon may be identical. An archeopyle was not identified with certainty. It is with some hesitation that the taxon is attributed to Dinophyceae; alternatively it may be an acritarch.
Stratigraphic occurrence: The taxon is common below the Nivelle Horizon and extremely rare to absent above, and may thus be of stratigraphic importance in differentiating the Lixhe members from the overlying stratigraphic section. The similar taxon Prolixosphaeridium cf. nanum has a sharp decrease in abundance in the middle part of the argentaljunior Zone in the Hemmoor Quarry (at 47 m), according to Marheinecke (1992).
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Originally Hystrichosphaera pilosa forma nanus (name not validly published), subsequently Sentusidinium pilosum? subsp. nanus, thirdly Prolixosphaeridium nanus, fourthly (and now) Prolixosphaeridium? nanus. Questionable assignment: Fauconnier and Monteil in Fauconnier and Masure (2004, p.462–463).
The name Hystrichosphaera pilosa forma nanus was not validly published in Wetzel (1933b) since the species combination Hystrichosphaera pilosa was not validly published.
Holotype: O. Wetzel, 1933, pl.4, fig.23; Sarjeant, 1986, pl.2, figs.6-7
Age: Late Cretaceous
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Prolixosphaeridium? cf. nanum (O. Wetzel, 1933) Sarjeant, 1985
Figured in Schioler et al.: Plate IV, 4
Description: Schioler et al. 1997, p. 87, 89
Small oval microgranulate phragm covered with 30-50 mainly solid and flexible simple processes.
Dimensions (in µm, 5 specimens measured): length, 30 (34) 38; width, 15 (19) 21; length of processes, 5-12.
Discussion: This taxon resembles P. nanum in general shape and in size, but differs in having mainly solid processes. It closely resembles specimens assigned to Prolixosphaeridium cf. nanum by Marheinecke (1992) and specimens assigned to Micrhystrium piliferum by Harker et al. (1990). These and the present taxon may be identical. An archeopyle was not identified with certainty. It is with some hesitation that the taxon is attributed to Dinophyceae; alternatively it may be an acritarch.
Stratigraphic occurrence: The taxon is common below the Nivelle Horizon and extremely rare to absent above, and may thus be of stratigraphic importance in differentiating the Lixhe members from the overlying stratigraphic section. The similar taxon Prolixosphaeridium cf. nanum has a sharp decrease in abundance in the middle part of the argentaljunior Zone in the Hemmoor Quarry (at 47 m), according to Marheinecke (1992).
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