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Prolixosphaeridium parvispinum
Prolixosphaeridium parvispinum (Deflandre, 1937) Davey et al. 1969
Originally Hystrichosphaeridium xanthiopyxides var. parvispinum, subsequently
Hystrichosphaeridium parvispinum, thirdly Baltisphaeridium parvispinum (an acritarch species, fourthly (and now) Prolixosphaeridium parvispinum.
Taxonomic junior synonyms (at specific and varietal ranks): Prolixosphaeridium deirense, according to Davey and Verdier (1974, p.636–637) — however, Harding (1990b, p.46) retained Prolixosphaeridium deirense; Prolixosphaeridium elongatum, according to Lentin and Williams (1985, p.294).
This combination was not validly published in Davey et al. (1966, p.173), since these authors did not fully reference the basionym.
Holotype: Deflandre, 1937b, pl.16 (al. pl.13), fig.5; Fauconnier and Masure, 2004, pl.66, figs.5–6.
Age: Late Aptian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Prolixosphaeridium parvispinum (Deflandre, 1937b) Davey et al., 1969. Harding (1990) did not consider P.parvispinum to be a taxonomic senior synonym of P.deirense. He stated that P.parvispinum is a poorly defined species and pending possible reexamination of Deflandre’s type material, may not even be referable to Prolixosphaeridium. The emended diagnosis from Harding (1990, p.46). Ambitus prolate ovoidal, length; width ratio greater or equal 2:1, hypocyst apparently longer than epicyst. Apical paraplates greatly reduced in size with respect to total cyst diameter. Strong dorso-ventral compression unlikely as cyst found in variety of orientations. Differentiated autophragm equal or exceeding 1 µm. Surface sculpture is essentially comprised of a pseudoreticulum through the lumina of which protrude clavulae (equal to or greater than 0.5 µm in diameter), giving rise to a granular aspect under the light microscope. In certain places the clavulae are elongated and fuse with neighbouring ones to form solid cylindrical processes. The processes are nontabular and acuminate. Those specimens with a less dense covering of processes (<50) possess wider processes (>2 µm diameter) those more densely covered (>60) have narrower processes (<2um diameter). Paratabulation unknown but consistently shows only 5 precingular paraplates and an ai all separated by accessory sutures. This may indicate fusion of two precingular paraplates. Archeopyle type (tA), presumably involving four apicals as a free, simple polyplacoid operculum. Accessory archeopyle sutures developed in the precingulars. Paracingulum undifferentiated. Parasulcus only shown by position of ai after archeopyle formation and by slight reduction of process length. Size: body length less operculum 42-59 µm, width 22-32 µm, process length 7-15 µm.
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Original description: Deflandre, 1937, p.26: Hystrichosphaeridium xanthiopyxis var. parvispinum
Supplemental description: Cookson and Eisenack, 1958, p. 45: Hystrichosphaeridium parvispinum
Shell elongate oval with a distinct granular membrane and numerous short, sharply pointed spines, the tips of which are sometimes recurved.
Originally Hystrichosphaeridium xanthiopyxides var. parvispinum, subsequently
Hystrichosphaeridium parvispinum, thirdly Baltisphaeridium parvispinum (an acritarch species, fourthly (and now) Prolixosphaeridium parvispinum.
Taxonomic junior synonyms (at specific and varietal ranks): Prolixosphaeridium deirense, according to Davey and Verdier (1974, p.636–637) — however, Harding (1990b, p.46) retained Prolixosphaeridium deirense; Prolixosphaeridium elongatum, according to Lentin and Williams (1985, p.294).
This combination was not validly published in Davey et al. (1966, p.173), since these authors did not fully reference the basionym.
Holotype: Deflandre, 1937b, pl.16 (al. pl.13), fig.5; Fauconnier and Masure, 2004, pl.66, figs.5–6.
Age: Late Aptian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Prolixosphaeridium parvispinum (Deflandre, 1937b) Davey et al., 1969. Harding (1990) did not consider P.parvispinum to be a taxonomic senior synonym of P.deirense. He stated that P.parvispinum is a poorly defined species and pending possible reexamination of Deflandre’s type material, may not even be referable to Prolixosphaeridium. The emended diagnosis from Harding (1990, p.46). Ambitus prolate ovoidal, length; width ratio greater or equal 2:1, hypocyst apparently longer than epicyst. Apical paraplates greatly reduced in size with respect to total cyst diameter. Strong dorso-ventral compression unlikely as cyst found in variety of orientations. Differentiated autophragm equal or exceeding 1 µm. Surface sculpture is essentially comprised of a pseudoreticulum through the lumina of which protrude clavulae (equal to or greater than 0.5 µm in diameter), giving rise to a granular aspect under the light microscope. In certain places the clavulae are elongated and fuse with neighbouring ones to form solid cylindrical processes. The processes are nontabular and acuminate. Those specimens with a less dense covering of processes (<50) possess wider processes (>2 µm diameter) those more densely covered (>60) have narrower processes (<2um diameter). Paratabulation unknown but consistently shows only 5 precingular paraplates and an ai all separated by accessory sutures. This may indicate fusion of two precingular paraplates. Archeopyle type (tA), presumably involving four apicals as a free, simple polyplacoid operculum. Accessory archeopyle sutures developed in the precingulars. Paracingulum undifferentiated. Parasulcus only shown by position of ai after archeopyle formation and by slight reduction of process length. Size: body length less operculum 42-59 µm, width 22-32 µm, process length 7-15 µm.
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Original description: Deflandre, 1937, p.26: Hystrichosphaeridium xanthiopyxis var. parvispinum
Supplemental description: Cookson and Eisenack, 1958, p. 45: Hystrichosphaeridium parvispinum
Shell elongate oval with a distinct granular membrane and numerous short, sharply pointed spines, the tips of which are sometimes recurved.