Back
Pseudoceratium expolitum
Pseudoceratium expolitum Brideaux, 1971
Tax. sr. synonym of Pseudoceratium regium C. Singh, 1971, according to Harker and Sarjeant, 1975.
Holotype: Brideaux, 1971, pl.30, fig.106
Locus typicus: Alberta, Canada
Stratum typicum: Middle-late Albian
Original description (Holotype): Brideaux, 1971, p.102
Total length of cyst, 158 µm: maximum width, 66 µm; lateral horn length, 28 µm; antapical horn length, 58 µm. Cyst elongate in the longitudinal axis, epitract and hypotract approximately equal. Central cyst body somewhat asymmetrical with one gently curved side and the other somewhat angular. Long, tapering apical horn, rounded at the apex; short lateral horn situated just at and below the point of maximum cyst body width, the apex rounded; one antapical horn, very stout basally, tapering to a more or less pointed apex. Cingulum and sulcul regions not developed. No evidence of tabulation other than the developing zig-zag break giving evidence of an incipient apical archeopyle with operculum formed of the apical horn and part of the epitract.
Description: Brideaux, 1971, p.102
Dinoflagellate cyst; cyst body essentially elongate-ovoid, somewhat asymmetrically developed, bearing one elongate, tapering apical horn, one lateral horn, which distorts the symmetry of the outline to a varying extent, and one asymmetrically placed, tapering antapical horn, the apex rounded (truncated) to acute. The cyst body has rounded contours and bulges slightly opposite the position of the lateral horn, about mid-way down the hypotract. Archeopyle apical, the margin zig-zag; the operculum includes the apical horn and part of the epitract. No evidence of cingulum or sulcus structure or tabulation noted on the specimens available for study. Wall appears thick and is smooth or occasionally scabrate to microreticulate, the latter probably due to corrosion. The ventral portion of the cyst body appears flattened, the dorsal side, slightly convex. A few specimens retain the essentially asymmetrical construction but have the horns reduced in size.
Dimensions: Total length on 21 specimens, 102-169 µm; maximum width on 24 specimens, 45-102 µm; lengths of horns: apical, 15-52 µm; lateral, 10-32 µm; antapical, 7-57 µm.
Affinities:
Brideaux, 1971, p.102: Several species similar to Pseudoceratium expolitum have been described and figured by Gocht (1957). P.? nudum Gocht 1957, p. 168; Pl. 18, figs. 3--4 and 6, is larger in size but shows some similarity in construction; it is difficult however to make a clear comparison from the illustrations. A second form, Pseudoceratium? sp. of Gocht 1957, p.169; Pl.18, fig.5, is also similar, but again is larger and appears to possess an internal body, a feature not evident in P. expolitum. It thus seems best to propose a new species for the specimens described above and to mention the similarities to the forms of Gocht.
Tax. sr. synonym of Pseudoceratium regium C. Singh, 1971, according to Harker and Sarjeant, 1975.
Holotype: Brideaux, 1971, pl.30, fig.106
Locus typicus: Alberta, Canada
Stratum typicum: Middle-late Albian
Original description (Holotype): Brideaux, 1971, p.102
Total length of cyst, 158 µm: maximum width, 66 µm; lateral horn length, 28 µm; antapical horn length, 58 µm. Cyst elongate in the longitudinal axis, epitract and hypotract approximately equal. Central cyst body somewhat asymmetrical with one gently curved side and the other somewhat angular. Long, tapering apical horn, rounded at the apex; short lateral horn situated just at and below the point of maximum cyst body width, the apex rounded; one antapical horn, very stout basally, tapering to a more or less pointed apex. Cingulum and sulcul regions not developed. No evidence of tabulation other than the developing zig-zag break giving evidence of an incipient apical archeopyle with operculum formed of the apical horn and part of the epitract.
Description: Brideaux, 1971, p.102
Dinoflagellate cyst; cyst body essentially elongate-ovoid, somewhat asymmetrically developed, bearing one elongate, tapering apical horn, one lateral horn, which distorts the symmetry of the outline to a varying extent, and one asymmetrically placed, tapering antapical horn, the apex rounded (truncated) to acute. The cyst body has rounded contours and bulges slightly opposite the position of the lateral horn, about mid-way down the hypotract. Archeopyle apical, the margin zig-zag; the operculum includes the apical horn and part of the epitract. No evidence of cingulum or sulcus structure or tabulation noted on the specimens available for study. Wall appears thick and is smooth or occasionally scabrate to microreticulate, the latter probably due to corrosion. The ventral portion of the cyst body appears flattened, the dorsal side, slightly convex. A few specimens retain the essentially asymmetrical construction but have the horns reduced in size.
Dimensions: Total length on 21 specimens, 102-169 µm; maximum width on 24 specimens, 45-102 µm; lengths of horns: apical, 15-52 µm; lateral, 10-32 µm; antapical, 7-57 µm.
Affinities:
Brideaux, 1971, p.102: Several species similar to Pseudoceratium expolitum have been described and figured by Gocht (1957). P.? nudum Gocht 1957, p. 168; Pl. 18, figs. 3--4 and 6, is larger in size but shows some similarity in construction; it is difficult however to make a clear comparison from the illustrations. A second form, Pseudoceratium? sp. of Gocht 1957, p.169; Pl.18, fig.5, is also similar, but again is larger and appears to possess an internal body, a feature not evident in P. expolitum. It thus seems best to propose a new species for the specimens described above and to mention the similarities to the forms of Gocht.