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Leberidocysta pergamentacea
Leberidocysta perpamentacea (Burger, 1980[a]) Burger, 1980[b]
Originally Palaeostomocystis, subsequently (and now) Leberidocysta?, thirdly Craspedodinium.
At the time of the transfer, Burger, 1980, questionably included this species in Leberidocysta.
Mehrotra and Sarjeant, 1984, transferred this species to Craspedodinium Cookson and Eisenack, 1974. Lentin and Williams, 1985, retained it in Leberidocysta.
Holotype: Burger 1980a, Pl. 47, fig. 3
Locus typicus: Surat Basin, Australia
Stratum typicum: Bungil Formation, Minmi Member. Cretaceous, early Aptian
Age: Aptian
Description: Burger 1980a, p. 88: Palaeostomocystis pergamentaceus
Shell in the form of an oval to spherical sac, with a small aperture (pylome?) at one end. In some specimens an operculum is still attached. Wall very probably single-layered, thin, psilate to punctate, usually folded, with a minutely and densely wrinkled, almost corrugate surface.
Dimensions: Length of sac (= apical diameter) of 19 specimens 52-(63)-82 Ám.
Distribution: An uncommon species in many marine assemblages from the Surat Basin.
Comments: P. pergamentaceus sp. nov. differs from other species of Palaeostomocystis by its extremely thin, and characteristically wrinkled wall. The presence of an inner membrane, indicating that the species would be cavate, was suggested in only a few species but not confirmed in most others. If an endophragm is present, the species will probably have to be transferred to the genus Hexagonifera.
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Emended description: Burger 1980b, p. 272: Leberidocysta? pergamentacea
Cavate, ellipsoidal or egg-shaped to subspherical, compressed specimens with rounded apical and antapical outline. Wall double-layered, periphragm punctate to psilate, with low concentric folds and a minutely wrinkled surface. Endocyst almost filling pericoel, outline usually obscured by periphragmic folds; endophragm very thin and psilate. In some specimens a small apical aperture is formed in the periphragm, an operculum is usually still attached. No aperture has been observed in the endophragm. There are no traces of a paracingulum, parasulcus, or other parasutures. Longest (apical) diameter of 19 specimens 52-(63)-82 Ám.
Distribution. A very rare form in the Gilbert River Formation (MFP 1792) and basal Rolling Downs Ciroup (MFP6322). More common in the Aptian and basal Albian of southeastern Queensland.
Comments. Burger (1980) suspected the species to be cavate, but this was difficult to verify as concentric folding of the periphragm usually obscures the outline of the endocyst. The specimen here illustrated is distinctly cavate and proves that the species is very probably a representative of the genus Leberidocysta. The aperture is small and presumably apical, although in some specimens it seems to be somewhat offset, but this might be the result of the specimen being compressed.
Originally Palaeostomocystis, subsequently (and now) Leberidocysta?, thirdly Craspedodinium.
At the time of the transfer, Burger, 1980, questionably included this species in Leberidocysta.
Mehrotra and Sarjeant, 1984, transferred this species to Craspedodinium Cookson and Eisenack, 1974. Lentin and Williams, 1985, retained it in Leberidocysta.
Holotype: Burger 1980a, Pl. 47, fig. 3
Locus typicus: Surat Basin, Australia
Stratum typicum: Bungil Formation, Minmi Member. Cretaceous, early Aptian
Age: Aptian
Description: Burger 1980a, p. 88: Palaeostomocystis pergamentaceus
Shell in the form of an oval to spherical sac, with a small aperture (pylome?) at one end. In some specimens an operculum is still attached. Wall very probably single-layered, thin, psilate to punctate, usually folded, with a minutely and densely wrinkled, almost corrugate surface.
Dimensions: Length of sac (= apical diameter) of 19 specimens 52-(63)-82 Ám.
Distribution: An uncommon species in many marine assemblages from the Surat Basin.
Comments: P. pergamentaceus sp. nov. differs from other species of Palaeostomocystis by its extremely thin, and characteristically wrinkled wall. The presence of an inner membrane, indicating that the species would be cavate, was suggested in only a few species but not confirmed in most others. If an endophragm is present, the species will probably have to be transferred to the genus Hexagonifera.
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Emended description: Burger 1980b, p. 272: Leberidocysta? pergamentacea
Cavate, ellipsoidal or egg-shaped to subspherical, compressed specimens with rounded apical and antapical outline. Wall double-layered, periphragm punctate to psilate, with low concentric folds and a minutely wrinkled surface. Endocyst almost filling pericoel, outline usually obscured by periphragmic folds; endophragm very thin and psilate. In some specimens a small apical aperture is formed in the periphragm, an operculum is usually still attached. No aperture has been observed in the endophragm. There are no traces of a paracingulum, parasulcus, or other parasutures. Longest (apical) diameter of 19 specimens 52-(63)-82 Ám.
Distribution. A very rare form in the Gilbert River Formation (MFP 1792) and basal Rolling Downs Ciroup (MFP6322). More common in the Aptian and basal Albian of southeastern Queensland.
Comments. Burger (1980) suspected the species to be cavate, but this was difficult to verify as concentric folding of the periphragm usually obscures the outline of the endocyst. The specimen here illustrated is distinctly cavate and proves that the species is very probably a representative of the genus Leberidocysta. The aperture is small and presumably apical, although in some specimens it seems to be somewhat offset, but this might be the result of the specimen being compressed.