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Pterodinium pterotum
Pterodinium pterotum (Cookson and Eisenack, 1958, p.50, pl.11, fig.7) Pavlishina, 1990, p.95. Emendation: Pavlishina, 1990, p.95, as Pterodinium? pterotum.
Originally Cymatiosphaera, subsequently Hystrichosphaera, thirdly Cymatiosphaera, fourthly Spiniferites, fifthly Pterodinium. Pavlishina 1990 questionably included this species in Pterodinium.
Taxonomic senior synonym: Cymatiosphaera (as and now Pterodinium) cingulata, according to Below (1981a, p.114) — however, Pavlishina (1990, p.95) retained Cymatiosphaera (now Pterodinium?) pterota.
Taxonomic junior synonyms: Hystrichosphaera (as Spiniferites) crassimurata, according to Kjellström (1973, p.44) and Pavlishina (1990, p.95); (at specific rank) Hystrichosphaera cingulata var. polygonalis, according to Pavlishina (1990, p.95) — however, Paul et al. (1994, p.722) retained Hystrichosphaera cingulata subsp. polygonalis (as Pterodinium cingulatum subsp. polygonale).
Holotype: Cookson and Eisenack, 1958, pl.11, fig.7
Locus typicus: Seismic shot hole B 2, Gingin area, W Australia
Stratum typicum: Albian
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Original description: Cookson and Eisenack 1958, p. 50: Cymatiophaera pterota
Shell spherical, smooth, its surface divided into large fields by thin, smooth, relatively, high membranes perpendicular to the surface. The margins of the membrane are frequently concave and sometimes minutely serrated.
Dimensions: Type: Overall diameter 66 µm, shell 43 µm; overall range 52-85 µm. Ratio of overall diameter to shell 1.4-1.5.
Comments: C. pterota diifers from C. wetzeli Defl., a German Upper Cretaceous species, in the regular form of the fields and the distinctly higher membranes.
Age and Occurrence: Upper Cretaceous (Campanian to Lower Maastrichtina): Korojon Calcarenite, W.A., Wapet"s Rough Range Well no. 4 at 1384-86 ft.; Upper Cretaceous (cenomanina to Lower Turonian): Gearle Siltstone, W.A., Wapet"s Rough Range Well. no. 5 at 1570 ft.; Probably Lower Cretaceous (Albian): Gingin, W.A., Seismic shot hole B.2 at 230 ft.
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Description: Pavlishina 1990, p. 95
Cysts proximate to proximocavate with spherical central body. Suturocavate (Benedek et al., 1982); phragm composed of two layers in close contact at the centrall region of the paraplates but separating along the cingulum and the parasutures. The periphragm forms high parasutural crests that demarcate the boundaries between the seperate paraplates. At places these crests are broader at the base, then narrow distally in the form of an inverted V. At the edges of the paraplates they stick together and form thickenings that look like outgrows. The outline of the paraplates at the base of the crests is roundly polygonal and this indicates the cavation. The paratabulation of gonyaulax type, formula 1-4", 6", 6c, 5"", l p, 1"". The archaeopyle is precingular formed by the loss of 3".
Remarks and discussion. Pavlishina 1990, p. 95
The present emendation of the diagnosis of P. ? pterotum concerns mainly the suturocavate character of its representatives. This makes questionable the appurtenance of this species to the genus Pterodinium. The suturocavation can he observed not only at the Bulgarian material but also at the fossils figured before by different authors. Davey and Williams (1966) proposed the new species Hystrichosphaera crassimurata Davey & Williams =Pterodinium ? pterotum (Cookson & Eisenack, 1958). Characteristic features of their species are the "pearl-like" thickenings of the phragm over the intratabular areas. The rotundity of the ""pearls" indicate stratification into endo- and periphragm laterally from the parasutures. The crests have the form of an inverted V. The same can be seen on the material figured by Clarke e & Verdier (1967). Their subspecies Hystrichosphaera cingulata var. polygonalis is characterized by concentric striae around the boundaries of the paraplates. That indicates stratification over the intratabular areas.
The presence of "pearl-like" caverns, located between the endo- and periphragm, as well as the existence of V-shaped crests at some of the specimens have also been pointed out by B e I o w (1981, p. 114) when describing Pterodinium cingulalum ssp. cingulalum (O. Wetzel, 1933) Below, 1981, although it is not sufficiently clear on the photographs offered by him.
Everything said so far justifies me in employing the term "suturocavate", coined by Benedeck, Gocht & Sarjeant (1982) in the diagnosis of P.? pterotum. This species differs from P. ? cingulatum ssp. cingulatum in being suturocavate in character. In the latter there is stratification into endo- and periphragm only in the region of the parasutures as the periphragm forms high crests.
Occurrence. The species is quite frequent in the investigated section. It was found in samples 446 and 447.
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Originally Cymatiosphaera, subsequently Hystrichosphaera, thirdly Cymatiosphaera, fourthly Spiniferites, fifthly Pterodinium. Pavlishina 1990 questionably included this species in Pterodinium.
Taxonomic senior synonym: Cymatiosphaera (as and now Pterodinium) cingulata, according to Below (1981a, p.114) — however, Pavlishina (1990, p.95) retained Cymatiosphaera (now Pterodinium?) pterota.
Taxonomic junior synonyms: Hystrichosphaera (as Spiniferites) crassimurata, according to Kjellström (1973, p.44) and Pavlishina (1990, p.95); (at specific rank) Hystrichosphaera cingulata var. polygonalis, according to Pavlishina (1990, p.95) — however, Paul et al. (1994, p.722) retained Hystrichosphaera cingulata subsp. polygonalis (as Pterodinium cingulatum subsp. polygonale).
Holotype: Cookson and Eisenack, 1958, pl.11, fig.7
Locus typicus: Seismic shot hole B 2, Gingin area, W Australia
Stratum typicum: Albian
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Original description: Cookson and Eisenack 1958, p. 50: Cymatiophaera pterota
Shell spherical, smooth, its surface divided into large fields by thin, smooth, relatively, high membranes perpendicular to the surface. The margins of the membrane are frequently concave and sometimes minutely serrated.
Dimensions: Type: Overall diameter 66 µm, shell 43 µm; overall range 52-85 µm. Ratio of overall diameter to shell 1.4-1.5.
Comments: C. pterota diifers from C. wetzeli Defl., a German Upper Cretaceous species, in the regular form of the fields and the distinctly higher membranes.
Age and Occurrence: Upper Cretaceous (Campanian to Lower Maastrichtina): Korojon Calcarenite, W.A., Wapet"s Rough Range Well no. 4 at 1384-86 ft.; Upper Cretaceous (cenomanina to Lower Turonian): Gearle Siltstone, W.A., Wapet"s Rough Range Well. no. 5 at 1570 ft.; Probably Lower Cretaceous (Albian): Gingin, W.A., Seismic shot hole B.2 at 230 ft.
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Description: Pavlishina 1990, p. 95
Cysts proximate to proximocavate with spherical central body. Suturocavate (Benedek et al., 1982); phragm composed of two layers in close contact at the centrall region of the paraplates but separating along the cingulum and the parasutures. The periphragm forms high parasutural crests that demarcate the boundaries between the seperate paraplates. At places these crests are broader at the base, then narrow distally in the form of an inverted V. At the edges of the paraplates they stick together and form thickenings that look like outgrows. The outline of the paraplates at the base of the crests is roundly polygonal and this indicates the cavation. The paratabulation of gonyaulax type, formula 1-4", 6", 6c, 5"", l p, 1"". The archaeopyle is precingular formed by the loss of 3".
Remarks and discussion. Pavlishina 1990, p. 95
The present emendation of the diagnosis of P. ? pterotum concerns mainly the suturocavate character of its representatives. This makes questionable the appurtenance of this species to the genus Pterodinium. The suturocavation can he observed not only at the Bulgarian material but also at the fossils figured before by different authors. Davey and Williams (1966) proposed the new species Hystrichosphaera crassimurata Davey & Williams =Pterodinium ? pterotum (Cookson & Eisenack, 1958). Characteristic features of their species are the "pearl-like" thickenings of the phragm over the intratabular areas. The rotundity of the ""pearls" indicate stratification into endo- and periphragm laterally from the parasutures. The crests have the form of an inverted V. The same can be seen on the material figured by Clarke e & Verdier (1967). Their subspecies Hystrichosphaera cingulata var. polygonalis is characterized by concentric striae around the boundaries of the paraplates. That indicates stratification over the intratabular areas.
The presence of "pearl-like" caverns, located between the endo- and periphragm, as well as the existence of V-shaped crests at some of the specimens have also been pointed out by B e I o w (1981, p. 114) when describing Pterodinium cingulalum ssp. cingulalum (O. Wetzel, 1933) Below, 1981, although it is not sufficiently clear on the photographs offered by him.
Everything said so far justifies me in employing the term "suturocavate", coined by Benedeck, Gocht & Sarjeant (1982) in the diagnosis of P.? pterotum. This species differs from P. ? cingulatum ssp. cingulatum in being suturocavate in character. In the latter there is stratification into endo- and periphragm only in the region of the parasutures as the periphragm forms high crests.
Occurrence. The species is quite frequent in the investigated section. It was found in samples 446 and 447.
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