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Rhynchodiniopsis perforans
Rhynchidiniopsis perforans (Cookson and Eisenack, 1958) Sarjeant, 1982
Now Cribroperidinium?. Originally Gonyaulax, subsequently Gonyaulacysta, thirdly Leptodinium?, fourthly Rhynchodiniopsis, fifthly Cribroperidinium, sixthly (and now) Cribroperidinium?.
Holotype: Cookson and Eisenack, 1958, pl.2, fig.1, text-figs.8-9; Jan du Chêne et al., 1986, pl.32, fig.2
Locus typicus: Omatia, Papua
Stratum typicum: Late Jurassic
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 - 168 x 109 µm. Range - 136-168 x 93-109 µm.
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.
Now Cribroperidinium?. Originally Gonyaulax, subsequently Gonyaulacysta, thirdly Leptodinium?, fourthly Rhynchodiniopsis, fifthly Cribroperidinium, sixthly (and now) Cribroperidinium?.
Holotype: Cookson and Eisenack, 1958, pl.2, fig.1, text-figs.8-9; Jan du Chêne et al., 1986, pl.32, fig.2
Locus typicus: Omatia, Papua
Stratum typicum: Late Jurassic
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 - 168 x 109 µm. Range - 136-168 x 93-109 µm.
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.