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Cribroperidinium perforans
Cribroperidinium ?perforans (Cookson and Eisenack, 1958, p.30-32, pl.2, figs.1-4,7-8; text-figs.8-9) Morgan, 1980, p.21.
Originally Gonyaulax (Appendix B), subsequently Gonyaulacysta, thirdly Leptodinium?, fourthly Rhynchodiniopsis, fifthly Cribroperidinium, sixthly (and now) Cribroperidinium?. Questionable assignment: Helenes (1984, p.130).
Holotype: Cookson and Eisenack, 1958, pl.2, fig.1; text-figs.8-9; Jan du Chêne et al., 1986a, pl.32, fig.2.
Locus typicus: Omatia, Papua
Age: Late Jurassic.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cribroperidinium perforans (Cookson and Eisenack, 1958) Morgan, 1980. According to Cookson and Eisenack (1958, p.32) this species has a distinctly helicoidal girdle, and a conical epitheca surmounted by a well developed, bluntly pointed horn. Wall of theca thin, smooth, ornamented to a varying degree by the thin perforated membrane that borders the plates and, more especially, the cingulum which is frequently almost hidden by a lacy network. A similar ornament is usually well developed in the mid-dorsal region of the hypocyst from which it extends as a prominent projection beyond the antapex. Plate 1' is especially narrow. Size: 136-168 x 93-109 µm.
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Original description: Cookson and Eisenack, 1958, p. 32: Gonyaulax perforans
Theca longer than broad with a distinctly helicoid girdle. Epitheca conical surmounted by a well-developed bluntly-pointed horn. Hypotheca more rounded than epitheca. Wall of theca thin, smooth, ornamented to a varying degree by a thin perforated membrane that borderthe plates and, more especially, the transverse furrow which is frequently almost hidden by a lacy network. A similar ornament is usually well developed in the mid-dorsal region of the hypotheca from which it extends as a prominent projection beyond the antapex. The longitudinal furrow which passes into the epitheca and to the antapex is unornamented exept at the antapex. The plate 1' which reaches to the horn is especially thin. In a few specimens which possibly represent a distinct species, the external ornament is more strongly developed, especially in the region of the girdle.
Dimensions: Type 168x109 Ám. Range 136-168x93-109 Ám.
Affinities:
Cookson and Eisenack, 1958, p. 32: Gonyaulax perforans is clearly related to G. scottii but differs in its shape, thinner wall, the more prominent antapical boss and the structure of the external ornament. In G. scottii the processes of which the membranes ornamenting the theca are constructed, although fused distally, are ofthe individually visible whereas in G. perforans the membranes have a more continuous texture with more or less numerous perforations of various sizes. Furthermore the limits of the plates are more heavily ornamented in g. scottii than in G. perforans.
Originally Gonyaulax (Appendix B), subsequently Gonyaulacysta, thirdly Leptodinium?, fourthly Rhynchodiniopsis, fifthly Cribroperidinium, sixthly (and now) Cribroperidinium?. Questionable assignment: Helenes (1984, p.130).
Holotype: Cookson and Eisenack, 1958, pl.2, fig.1; text-figs.8-9; Jan du Chêne et al., 1986a, pl.32, fig.2.
Locus typicus: Omatia, Papua
Age: Late Jurassic.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cribroperidinium perforans (Cookson and Eisenack, 1958) Morgan, 1980. According to Cookson and Eisenack (1958, p.32) this species has a distinctly helicoidal girdle, and a conical epitheca surmounted by a well developed, bluntly pointed horn. Wall of theca thin, smooth, ornamented to a varying degree by the thin perforated membrane that borders the plates and, more especially, the cingulum which is frequently almost hidden by a lacy network. A similar ornament is usually well developed in the mid-dorsal region of the hypocyst from which it extends as a prominent projection beyond the antapex. Plate 1' is especially narrow. Size: 136-168 x 93-109 µm.
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Original description: Cookson and Eisenack, 1958, p. 32: Gonyaulax perforans
Theca longer than broad with a distinctly helicoid girdle. Epitheca conical surmounted by a well-developed bluntly-pointed horn. Hypotheca more rounded than epitheca. Wall of theca thin, smooth, ornamented to a varying degree by a thin perforated membrane that borderthe plates and, more especially, the transverse furrow which is frequently almost hidden by a lacy network. A similar ornament is usually well developed in the mid-dorsal region of the hypotheca from which it extends as a prominent projection beyond the antapex. The longitudinal furrow which passes into the epitheca and to the antapex is unornamented exept at the antapex. The plate 1' which reaches to the horn is especially thin. In a few specimens which possibly represent a distinct species, the external ornament is more strongly developed, especially in the region of the girdle.
Dimensions: Type 168x109 Ám. Range 136-168x93-109 Ám.
Affinities:
Cookson and Eisenack, 1958, p. 32: Gonyaulax perforans is clearly related to G. scottii but differs in its shape, thinner wall, the more prominent antapical boss and the structure of the external ornament. In G. scottii the processes of which the membranes ornamenting the theca are constructed, although fused distally, are ofthe individually visible whereas in G. perforans the membranes have a more continuous texture with more or less numerous perforations of various sizes. Furthermore the limits of the plates are more heavily ornamented in g. scottii than in G. perforans.