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Astrocysta ampla
Astrocysta ampla, (Harland, 1973), Harker and Sarjeant, 1975
Combination not validly published: basionym not fully referenced.
Originally Lejeunia (generic name illegitimate), subsequently Astrocysta (combination not validly published), thirdly Palaeoperidinium.
Taxonomic senior synonym: Palaeoperidinium cretaceum, according to Harker and Sarjeant in Harker et al. (1990, p.128).
Holotype: Harland, 1973, pl.84, fig.1
Locus typicus: S Alberta, Canada
Stratum typicum: Late Campanian
Age: Late Campanian
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Original description: [Harland, 1973, p. 673-674]:
Diagnosis:
Proximate cyst, rhomboidal in shape, probably made up of autophragm only.
Test granulate, scabrate and/or reticulate.
No tabulation visible.
Cingulum usually conspicuous, planar, approximately 5 µm wide, delimited by raised sutures.
apical horn, distally oblate; two antapical horns one of which generally larger than the other.
Archeopyle apical.
Description:
It is possible that a second wall layer, closely adpressed, is present. Only one or two specimens show an apical archeopyle. Norris has observed transapical archeopyles in specimens with the same gross morphology. The Bearpaw specimens appear to have had one or two antapical plates making up the operculum. The antapical horns distally evexate and one was seen to carry small spinules.
Dimensions:
Holotype: Length 149.0 µm; breadth 108.0 µm. Range: Length 70.0 (116.3) 154.0 µm; breadth 68.0 (97.0) 108.0 µm.
Fifty specimens measured out of a studied population of eighty-nine.
Affinities:
This species differs from L. tricuspis in lacking the vertical striations, the acuminate antapical horns, and the coarse 'ornamentation'. Doubt is expressed in the generic assignment because of uncertainties in the nature of the archeopyle in this species and in the genus. The archeopyle as seen in the holotype is perfectly clear and does not appear to be of accidental origin. Evitt (pers. comm.) has commented on the resemblance of the small folds, often observed on the test of these cysts, to growth lines such as those exhibited by Palaeoperidinium pyrophorum (Ehrenberg). Its affinities are unknown.
Combination not validly published: basionym not fully referenced.
Originally Lejeunia (generic name illegitimate), subsequently Astrocysta (combination not validly published), thirdly Palaeoperidinium.
Taxonomic senior synonym: Palaeoperidinium cretaceum, according to Harker and Sarjeant in Harker et al. (1990, p.128).
Holotype: Harland, 1973, pl.84, fig.1
Locus typicus: S Alberta, Canada
Stratum typicum: Late Campanian
Age: Late Campanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Harland, 1973, p. 673-674]:
Diagnosis:
Proximate cyst, rhomboidal in shape, probably made up of autophragm only.
Test granulate, scabrate and/or reticulate.
No tabulation visible.
Cingulum usually conspicuous, planar, approximately 5 µm wide, delimited by raised sutures.
apical horn, distally oblate; two antapical horns one of which generally larger than the other.
Archeopyle apical.
Description:
It is possible that a second wall layer, closely adpressed, is present. Only one or two specimens show an apical archeopyle. Norris has observed transapical archeopyles in specimens with the same gross morphology. The Bearpaw specimens appear to have had one or two antapical plates making up the operculum. The antapical horns distally evexate and one was seen to carry small spinules.
Dimensions:
Holotype: Length 149.0 µm; breadth 108.0 µm. Range: Length 70.0 (116.3) 154.0 µm; breadth 68.0 (97.0) 108.0 µm.
Fifty specimens measured out of a studied population of eighty-nine.
Affinities:
This species differs from L. tricuspis in lacking the vertical striations, the acuminate antapical horns, and the coarse 'ornamentation'. Doubt is expressed in the generic assignment because of uncertainties in the nature of the archeopyle in this species and in the genus. The archeopyle as seen in the holotype is perfectly clear and does not appear to be of accidental origin. Evitt (pers. comm.) has commented on the resemblance of the small folds, often observed on the test of these cysts, to growth lines such as those exhibited by Palaeoperidinium pyrophorum (Ehrenberg). Its affinities are unknown.