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Cribroperidinium auctificum
Cribroperidinium auctificum (Brideaux, 1971) Stover and Evitt, 1978
Originally Gonyaulacysta, subsequently (and now) Cribroperidinium.
Holotype: Brideaux, 1971, pl.23, figs.40-41, text-fig.9a,b; Jan du Chêne et al., 1986, pl.30, figs.7-8
Locus typicus: Alberta, Canada
Stratum typicum: Late Albian
Original description (Holotype): Brideaux, 1971, p.82: Gonyaulacysta auctifica
Length, 12 Ám; width, 118 Ám; apical horn, 22 Ám. Main cyst shape approximately pentagonal; epitract including apical horn a little longer than the hypotract; apical horn tapering, rounded at the apex. Cingulum helicoid, sinistral, outlined by low, slightly irregular ledges, displacement about one and one-half cingulum widths. A portion of cingulum below the archeopyle is lost as part of the operculum (plate 3"). Sulcus wider antapically, extending onto the epitract, terminated apically by plate 1" and antapically by plate 1"""" and plate 1p. Tabulation determined as 4", 6", 0c, 6-?7""", 1-?2p, ?pv, 1"""", 4s. Plate 3" is small and triangular, situated just above the archeopyle; the sulcul plates are faintly outlined but distinct; plate 2s is taken as belonging to the sulcul region and not to the post-cingular series. The tabulation pattern on the ventral hypotract is complex and has not been fully determined.
Description: Brideaux, 1971, p. 82: Gonyaulacysta auctifica
Dinoflagellate cyst; overall outline pentagonal-rounded; prominent apical horn. Wall 3-5 Á thick, apparently two-layered, the outer layer thinner, laevigate to scabrate, and forming the sutures. Helicoid, sinistral transverse cingulum, displaced about one and one-half cingulum widths and bounded by raised sutures; sulcus somewhat sinuous or flask-shaped, with up to 4 sulcul plates; the sulcus approximately equally divided between the epitract and hypotract, truncated by plate 1" apically and plates 1"""" and 1p antapically. Tabulation pattern complex, outlined by low, membranous, sinuous to digitate sutures, these sometimes clearly reflected by parallel intertabular crests. Epitractal tabulation determined as 4", 6", with plate3" crowning the archeopyle and typically triangular and elongate in shape. Tabulation of the hypotract complex, especially in the sulcul region; partially determined as 0c, 6-?9""", 1p, 1"""", 3-?4 s. On the holotype, 7 post-cingular fields may be discerned; however the L-shaped plate 3""" may be actually part of the plate labelled as 4""". If this suture were interpreted as superfluous, only 6 post-cingular plates would remain. If the plate considered 2s were included as part of 1""", only 6 fields would remain. Other specimens show as many as 9 fields on the hypotract, when all such enclosed areas are considered as plates. Archeopyle precingular, expanded; operculum consists of the plate 3" plus the adjacent portion of the cingulum.
Dimensions: Length on 22 measured specimens, 112-147 Ám; width on 21 measured specimens, 77-118 Ám; apical horn length on 20 specimens, 22--35 Ám. Total of 30 specimens recovered.
Remarks: The illustrations of this species indicate the complexity of the hypotractal plating pattern and the difficulty of distinguishing true plates and reflected sutures which are intertabular in position. Davey (1969) has discussed similar hypotractal patterns in the species Cribroperidinium intricatum Davey, showing how the complex pattern of fields may be reduced to the more typical Gonyaulacysta-type pattern by removal of certain sutures. Because the epitract tabulation does not attain the complexity of Cribroperidinium, the new species described here is retained in Gonyaulacysta.
Affinities:
Brideaux, 1971, p.83: Gonyaulacysta auctifica
Gonyaulacysta auctifica is distinguished by its combination of tabulation, archeopyle type and shape. The small plate 3", the inclusion of the adjacent portion of the cingulum in the operculum, and the complex ventral hypotract pattern are diagnostic. Other associated features include the long apical horn and two-layered wall with the thick inner layer (endophragm).
Other forms possessing an expanded precingular archeopyle and having an operculum including plate 3" and the adjacent cingulum differ in construction of the cingulum and in tabulation. These are: Palaeoperidinium castanea Deflandre 1935 in Deflandre (1936), Pl.6, fig.4; and the drawing by Lejeune-Carpentier (1946, p.l90; fig.2) of the specimen figured by W. Wetzel (1933, p.161; Pl.2, fig.4) and called Peridinium ventriosum Wetzel.
Originally Gonyaulacysta, subsequently (and now) Cribroperidinium.
Holotype: Brideaux, 1971, pl.23, figs.40-41, text-fig.9a,b; Jan du Chêne et al., 1986, pl.30, figs.7-8
Locus typicus: Alberta, Canada
Stratum typicum: Late Albian
Original description (Holotype): Brideaux, 1971, p.82: Gonyaulacysta auctifica
Length, 12 Ám; width, 118 Ám; apical horn, 22 Ám. Main cyst shape approximately pentagonal; epitract including apical horn a little longer than the hypotract; apical horn tapering, rounded at the apex. Cingulum helicoid, sinistral, outlined by low, slightly irregular ledges, displacement about one and one-half cingulum widths. A portion of cingulum below the archeopyle is lost as part of the operculum (plate 3"). Sulcus wider antapically, extending onto the epitract, terminated apically by plate 1" and antapically by plate 1"""" and plate 1p. Tabulation determined as 4", 6", 0c, 6-?7""", 1-?2p, ?pv, 1"""", 4s. Plate 3" is small and triangular, situated just above the archeopyle; the sulcul plates are faintly outlined but distinct; plate 2s is taken as belonging to the sulcul region and not to the post-cingular series. The tabulation pattern on the ventral hypotract is complex and has not been fully determined.
Description: Brideaux, 1971, p. 82: Gonyaulacysta auctifica
Dinoflagellate cyst; overall outline pentagonal-rounded; prominent apical horn. Wall 3-5 Á thick, apparently two-layered, the outer layer thinner, laevigate to scabrate, and forming the sutures. Helicoid, sinistral transverse cingulum, displaced about one and one-half cingulum widths and bounded by raised sutures; sulcus somewhat sinuous or flask-shaped, with up to 4 sulcul plates; the sulcus approximately equally divided between the epitract and hypotract, truncated by plate 1" apically and plates 1"""" and 1p antapically. Tabulation pattern complex, outlined by low, membranous, sinuous to digitate sutures, these sometimes clearly reflected by parallel intertabular crests. Epitractal tabulation determined as 4", 6", with plate3" crowning the archeopyle and typically triangular and elongate in shape. Tabulation of the hypotract complex, especially in the sulcul region; partially determined as 0c, 6-?9""", 1p, 1"""", 3-?4 s. On the holotype, 7 post-cingular fields may be discerned; however the L-shaped plate 3""" may be actually part of the plate labelled as 4""". If this suture were interpreted as superfluous, only 6 post-cingular plates would remain. If the plate considered 2s were included as part of 1""", only 6 fields would remain. Other specimens show as many as 9 fields on the hypotract, when all such enclosed areas are considered as plates. Archeopyle precingular, expanded; operculum consists of the plate 3" plus the adjacent portion of the cingulum.
Dimensions: Length on 22 measured specimens, 112-147 Ám; width on 21 measured specimens, 77-118 Ám; apical horn length on 20 specimens, 22--35 Ám. Total of 30 specimens recovered.
Remarks: The illustrations of this species indicate the complexity of the hypotractal plating pattern and the difficulty of distinguishing true plates and reflected sutures which are intertabular in position. Davey (1969) has discussed similar hypotractal patterns in the species Cribroperidinium intricatum Davey, showing how the complex pattern of fields may be reduced to the more typical Gonyaulacysta-type pattern by removal of certain sutures. Because the epitract tabulation does not attain the complexity of Cribroperidinium, the new species described here is retained in Gonyaulacysta.
Affinities:
Brideaux, 1971, p.83: Gonyaulacysta auctifica
Gonyaulacysta auctifica is distinguished by its combination of tabulation, archeopyle type and shape. The small plate 3", the inclusion of the adjacent portion of the cingulum in the operculum, and the complex ventral hypotract pattern are diagnostic. Other associated features include the long apical horn and two-layered wall with the thick inner layer (endophragm).
Other forms possessing an expanded precingular archeopyle and having an operculum including plate 3" and the adjacent cingulum differ in construction of the cingulum and in tabulation. These are: Palaeoperidinium castanea Deflandre 1935 in Deflandre (1936), Pl.6, fig.4; and the drawing by Lejeune-Carpentier (1946, p.l90; fig.2) of the specimen figured by W. Wetzel (1933, p.161; Pl.2, fig.4) and called Peridinium ventriosum Wetzel.