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Spinidinium styloniferum
Spinidinium styloniferum Cookson and Eisenack, 1962
Holotype: Cookson and Eisenack, 1962, pl.1, figs.1-2; Morgan, 1975, pl.2, fig.1
Locus typicus: Rakich"s bore, Caversham, Perth Basin, Australia
Stratum typicum: ?Aptian-Albian
Original description: Cookson and Eisenack, 1962, p. 489
Shell small; ventral surface deeply concave; epitheca slightly longer than hypotheca; apical horn short, hollow; the end wall straight to concave, usually with a median, downwardly directed, tonue-like thickening and a few upwardly directed basal spines; antapex oblique or rounded, with a short projection on one side. Girdle well-defined, with decided marginal indentations; longitudinal furrow proportionately wide, especially in the hypotheca, narrowing in the epitheca to end shortly behind the apex.
Shell membrane two-layered, the inner layer smooth and thin, the outer layer somewhat thicker and ornamented with numerous short, finger-like processes or bluntly pointed spines, some of which outline the girdle, the longitudinal furrow, and the position of the eventual pylome. The outer layer frequently thickens appreciably toward one side of the apex to contribute, together with one or two more prominent spines, to the formation of the antapical projection. Pylome narrowly hoof-shaped.
Dimensions: Holotype: 53µm long, 42µm broad; range: 42-60µm long, 36-42µm broad.
Revised description: Morgan, 1975, p. 160
Cyst is thick walled, outline roughly pentagonal in dorsal-ventral view. The periphragm is drawn out into a broadly conical distally truncate apical horn, a steeply conical distally pointed left antapical horn, and a weakly developed right antapical horn. The cingulum is broad, divides the cyst into about equal parts, and is only offset slightly at the sulcus. The endophragm is approximately ellipsoidal; the two wall layers separate slightly at the base of the horns. The periphragm bears many solid rod-like projections with broadly rounded distal ends. The rod-like ornament is occasionally 2.5-5.0 µm long and 1.0-1.5 µm diameter, but more commonly is 2.0-4.0 µm long and 0.5-1.0 µm in diameter. The ornament is closely spaced and aligned along the cingulum margins, and peritabular to the reflected plate areas. Some specimens have dense intratabular ornament as well; all specimens lack ornament on the cingulum and sulcus. The archeopyle is intercalary, type Ia (2a only) elongate trapezoidal; the archeopyle is attached along the antapical margin.
Holotype: Cookson and Eisenack, 1962, pl.1, figs.1-2; Morgan, 1975, pl.2, fig.1
Locus typicus: Rakich"s bore, Caversham, Perth Basin, Australia
Stratum typicum: ?Aptian-Albian
Original description: Cookson and Eisenack, 1962, p. 489
Shell small; ventral surface deeply concave; epitheca slightly longer than hypotheca; apical horn short, hollow; the end wall straight to concave, usually with a median, downwardly directed, tonue-like thickening and a few upwardly directed basal spines; antapex oblique or rounded, with a short projection on one side. Girdle well-defined, with decided marginal indentations; longitudinal furrow proportionately wide, especially in the hypotheca, narrowing in the epitheca to end shortly behind the apex.
Shell membrane two-layered, the inner layer smooth and thin, the outer layer somewhat thicker and ornamented with numerous short, finger-like processes or bluntly pointed spines, some of which outline the girdle, the longitudinal furrow, and the position of the eventual pylome. The outer layer frequently thickens appreciably toward one side of the apex to contribute, together with one or two more prominent spines, to the formation of the antapical projection. Pylome narrowly hoof-shaped.
Dimensions: Holotype: 53µm long, 42µm broad; range: 42-60µm long, 36-42µm broad.
Revised description: Morgan, 1975, p. 160
Cyst is thick walled, outline roughly pentagonal in dorsal-ventral view. The periphragm is drawn out into a broadly conical distally truncate apical horn, a steeply conical distally pointed left antapical horn, and a weakly developed right antapical horn. The cingulum is broad, divides the cyst into about equal parts, and is only offset slightly at the sulcus. The endophragm is approximately ellipsoidal; the two wall layers separate slightly at the base of the horns. The periphragm bears many solid rod-like projections with broadly rounded distal ends. The rod-like ornament is occasionally 2.5-5.0 µm long and 1.0-1.5 µm diameter, but more commonly is 2.0-4.0 µm long and 0.5-1.0 µm in diameter. The ornament is closely spaced and aligned along the cingulum margins, and peritabular to the reflected plate areas. Some specimens have dense intratabular ornament as well; all specimens lack ornament on the cingulum and sulcus. The archeopyle is intercalary, type Ia (2a only) elongate trapezoidal; the archeopyle is attached along the antapical margin.