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Leberidocysta strigosa
From Fensome et al., 2019:
Leberidocysta strigosa Mantle, 2009b, p.109,110, pl.13, figs.11–13; text-fig.4. Holotype: Mantle, 2009b, pl.13, fig.11. Questionable assignment: Mantle (2009b, p.109). Age: Callovian.
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Original description: [Mantle, 2009b]:
Leberidocysta? strigosa
Plate 13, Figs 11-13; Text-fig. 4
Diagnosis: Cysts proximate, cavate; spherical, subspherical, or polygonal; small to medium-sized. Cyst wall 2-Iayered; endophragm thin, laevigate, scabrate, or uncommonly with few scattered grana; periphragm laevigate, extremely fine, commonly folded. A series of thin folds or ridges, concentric to the dorso-ventral outline, form a subcircular to rectangular shape on the cyst's ventral surface. Paratabulation indicated only by archeopyle and rare, low, parasutural ridges towards antapex. Archeopyle apical; operculum compound, attached dorsally.
Description: The endocyst is typically separated from the pericyst by less than 2 pm, making it difficult to observe the 2 wall layers; thus the cyst may appear acavate, and the folded and fine srructure of the periphragm adds to this effect. However, on well-preserved specimens the endo- and periphragms may both be observed, especially on the operculum. The folds or ridges (< 0.5 prm high) of the periphragm surface are commonly restricted to or are more abundant on the cyst's ventral surface; the most robust of these develop a subcircular to rectangular outline ca. 5-10 ptm from the ventral margin. The apical operculum, where evident, remains attached to the dorsal surface with tears extending 5-20 pm antapically.
Dimensions (20 specimens): Length of cyst (excluding operculum) 39 (47) 52 pm; maximum width of cyst 45 (49) 5a prm;
thickness of endophragm < 0.5 pm; thickness of periphragm < 0.2 pm.
Holotype: Slide no. 2, EF F24/0. CPC no. 39252;Pl. 13, Fig. 11. Length of cyst (including operculum) 52 ytm; maximum width of cyst 47 p,m; thickness of endophragm < o.s pm; thickness of periphragm < 0.2 ;rm.
Type locality: Timor Sea, Bayu-Undan Field, Challis-11 ST1, core 2 at 1552.5 m (Elang Formation).
Etymology: Lat., strigosws (lean, thin, meagre); with reference to the very fine wall structure of the cyst.
Remarks and comparison: This species is placed tentatively in Leberidocysta STOVER & EVITT 1978 because the type species, L. chlamydata (COOKSON & EISENACK) STOVER & EVITT 1978 (p.60), differs considerably in possessing an ovoidal endocyst with a coarser, verrucate endophragm, a broader pericoel, and a free operculum. Leberidocysta? pergamentacea (BURGER) BURGER 1980 (1980b: 272) from the Aptian
of the Surat Basin, Queensland, is the most closely comparable species; it possesses very thin endo- and periphragms, an attached apical operculum, and is commonly subspherical in outline. The periphragm of both species commonly exhibit concentric folds. However, the distribution and number of these folds enables clear distinction: L? pergamentacea has a much denser fold development, giving the surface a
wrinkled appearance, whereas the fewer folds on the ventral surface of L? strigosa are more prominent and are commonly conjoined or nearly continuous, thus outlining a roughly circulir or rectangular area. The new species, also has a slightly lesser equatorial diameter than L? pergamentacea.
Local occurrence.: Elang Formation; Ternia balmei Interval Zone (Subzone TB1) through Ctenidodinium ancorum Interval Zone: rare to common.
Leberidocysta strigosa Mantle, 2009b, p.109,110, pl.13, figs.11–13; text-fig.4. Holotype: Mantle, 2009b, pl.13, fig.11. Questionable assignment: Mantle (2009b, p.109). Age: Callovian.
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Original description: [Mantle, 2009b]:
Leberidocysta? strigosa
Plate 13, Figs 11-13; Text-fig. 4
Diagnosis: Cysts proximate, cavate; spherical, subspherical, or polygonal; small to medium-sized. Cyst wall 2-Iayered; endophragm thin, laevigate, scabrate, or uncommonly with few scattered grana; periphragm laevigate, extremely fine, commonly folded. A series of thin folds or ridges, concentric to the dorso-ventral outline, form a subcircular to rectangular shape on the cyst's ventral surface. Paratabulation indicated only by archeopyle and rare, low, parasutural ridges towards antapex. Archeopyle apical; operculum compound, attached dorsally.
Description: The endocyst is typically separated from the pericyst by less than 2 pm, making it difficult to observe the 2 wall layers; thus the cyst may appear acavate, and the folded and fine srructure of the periphragm adds to this effect. However, on well-preserved specimens the endo- and periphragms may both be observed, especially on the operculum. The folds or ridges (< 0.5 prm high) of the periphragm surface are commonly restricted to or are more abundant on the cyst's ventral surface; the most robust of these develop a subcircular to rectangular outline ca. 5-10 ptm from the ventral margin. The apical operculum, where evident, remains attached to the dorsal surface with tears extending 5-20 pm antapically.
Dimensions (20 specimens): Length of cyst (excluding operculum) 39 (47) 52 pm; maximum width of cyst 45 (49) 5a prm;
thickness of endophragm < 0.5 pm; thickness of periphragm < 0.2 pm.
Holotype: Slide no. 2, EF F24/0. CPC no. 39252;Pl. 13, Fig. 11. Length of cyst (including operculum) 52 ytm; maximum width of cyst 47 p,m; thickness of endophragm < o.s pm; thickness of periphragm < 0.2 ;rm.
Type locality: Timor Sea, Bayu-Undan Field, Challis-11 ST1, core 2 at 1552.5 m (Elang Formation).
Etymology: Lat., strigosws (lean, thin, meagre); with reference to the very fine wall structure of the cyst.
Remarks and comparison: This species is placed tentatively in Leberidocysta STOVER & EVITT 1978 because the type species, L. chlamydata (COOKSON & EISENACK) STOVER & EVITT 1978 (p.60), differs considerably in possessing an ovoidal endocyst with a coarser, verrucate endophragm, a broader pericoel, and a free operculum. Leberidocysta? pergamentacea (BURGER) BURGER 1980 (1980b: 272) from the Aptian
of the Surat Basin, Queensland, is the most closely comparable species; it possesses very thin endo- and periphragms, an attached apical operculum, and is commonly subspherical in outline. The periphragm of both species commonly exhibit concentric folds. However, the distribution and number of these folds enables clear distinction: L? pergamentacea has a much denser fold development, giving the surface a
wrinkled appearance, whereas the fewer folds on the ventral surface of L? strigosa are more prominent and are commonly conjoined or nearly continuous, thus outlining a roughly circulir or rectangular area. The new species, also has a slightly lesser equatorial diameter than L? pergamentacea.
Local occurrence.: Elang Formation; Ternia balmei Interval Zone (Subzone TB1) through Ctenidodinium ancorum Interval Zone: rare to common.