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Pseudoceratium eisenackii
Pseudoceratium eisenackii (Davey, 1969) Bint, 1986
Originally Cyclonephelium, subsequently Aptea, thirdly (and now) Pseudoceratium.
Taxonomic senior synonym: Aptea (now Pseudoceratium) polymorpha, according to Cookson and Eisenack (1974, p.74) — however, Below (1981a, p.7) retained Aptea eisenackii.
Holotype: Davey, 1969, pl.8, figs.3-4; pl.9, fig.4
Locus typicus: Saskatchewan, Canada
Stratum typicum: Albian
Original diagnosis: Davey, 1969, p.170: Cyclonephelium eisenackii
Shell subtriangular, flattened, with convex sides. Apical horn well developed; antapical horns, if present, very reduced. Greater part of shell surface ornamented by complex network of low crests and short, capitate processes. In centre of both dorsal and ventral sides there is a circular area devoid of ornamentation. Apical archaeopyle always present.
Dimensions: shell length 70-92 µm (4 complete specimens measured); shell length (operculum missing) 55 (63.1) 71 µm, width 66 (72.1) 84 µm, height of crests 2 (4.2) 7 µm.
Original description: Davey, 1969, p.170: Cyclonephelium eisenacki
The shell surface is ornamented by a very characteristic network of low crests or lamellae which are often broken, so forming isolated processes. A poorly-marked cingulum, outlined by the crests, is occasionally discernible. The apical operculum is often in position.
Affinities:
Bint, 1986, p.145: Psudoceratium eisenackii closely resembles P. securigerum which differs in having better developed horns and an ornament of discrete processes, a few of which may sometimes be linked in a linear arrangement. P. polymorphum differs in having a more closely spaced and interconnected ornament which is covered by an ectophragm.
Originally Cyclonephelium, subsequently Aptea, thirdly (and now) Pseudoceratium.
Taxonomic senior synonym: Aptea (now Pseudoceratium) polymorpha, according to Cookson and Eisenack (1974, p.74) — however, Below (1981a, p.7) retained Aptea eisenackii.
Holotype: Davey, 1969, pl.8, figs.3-4; pl.9, fig.4
Locus typicus: Saskatchewan, Canada
Stratum typicum: Albian
Original diagnosis: Davey, 1969, p.170: Cyclonephelium eisenackii
Shell subtriangular, flattened, with convex sides. Apical horn well developed; antapical horns, if present, very reduced. Greater part of shell surface ornamented by complex network of low crests and short, capitate processes. In centre of both dorsal and ventral sides there is a circular area devoid of ornamentation. Apical archaeopyle always present.
Dimensions: shell length 70-92 µm (4 complete specimens measured); shell length (operculum missing) 55 (63.1) 71 µm, width 66 (72.1) 84 µm, height of crests 2 (4.2) 7 µm.
Original description: Davey, 1969, p.170: Cyclonephelium eisenacki
The shell surface is ornamented by a very characteristic network of low crests or lamellae which are often broken, so forming isolated processes. A poorly-marked cingulum, outlined by the crests, is occasionally discernible. The apical operculum is often in position.
Affinities:
Bint, 1986, p.145: Psudoceratium eisenackii closely resembles P. securigerum which differs in having better developed horns and an ornament of discrete processes, a few of which may sometimes be linked in a linear arrangement. P. polymorphum differs in having a more closely spaced and interconnected ornament which is covered by an ectophragm.