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Limbicysta guttularis
Limbicysta guttularis Marshall 1989
Acritarch genus
Holotype. Plate 1, figs. 13, 14.
Locus typicus: Gippsland Basin, Southeastern Australia
Stratum typicum: Late Cretaceous
Description: Marshall 1989, p. 34
Cysts bear a distinct middorsal bulge that is often flattened to form a lateral fold. Dorso-ventral outline modified by an apical and two lateral horns of similar dimensions. Horns elongate, sub-conical and flared distally, tips bifurcated; branches with rounded outlines tapering distally. Outline of hypocyst bulbous; constricted just below equator, strongly expanded and broadly convex antapically. Cysts with one or two wall layers; bilayered specimens circumcavate to cornucavate. Endocyst occupies central part of pericyst; dorsoventral outline subcircular or oval with length greater than width. Endophragm smooth, 0.2-0.4 Ám thick. Periphragm smooth, often strongly crumpled; ca. 0.4 Ám thick around much of periphery of cyst, thins markedly and occasionally split apart along antapical margin. Zones of thinning often with an irregular outline and may extend along all or parts of antapical margin. On one specimen, the periphragm also seems to become thinner adjacent to apical horn (Plate 1, figs. 9, 10; Text-Figure 7A). This specimen also has a row of small spines less than 1 Ám high adjacent to base of right lateral horn. Parasulcal region often suggested on midventral surface by two longitudinal folds, which can extend over much of the cyst length.
Size. Pericyst length 84(102)116 Ám, width 71(86)118 Ám; 15 specimens measured. Endocyst length 44(52)66 Ám, 4 specimens measured; width 39 Ám, 1 specimen measured.
Comparison: Marshall 1989, p. 34
This species mainly differs from Limbicysta pediformis sp. nov. in having a bulbous hypocyst which lacks antapical horns, and either one or two wall layers. Although single-layered specimens are more common, frequent bilayered examples also occur.
Occurrence. Cook Cruise sample C4/87 21DDa.
Acritarch genus
Holotype. Plate 1, figs. 13, 14.
Locus typicus: Gippsland Basin, Southeastern Australia
Stratum typicum: Late Cretaceous
Description: Marshall 1989, p. 34
Cysts bear a distinct middorsal bulge that is often flattened to form a lateral fold. Dorso-ventral outline modified by an apical and two lateral horns of similar dimensions. Horns elongate, sub-conical and flared distally, tips bifurcated; branches with rounded outlines tapering distally. Outline of hypocyst bulbous; constricted just below equator, strongly expanded and broadly convex antapically. Cysts with one or two wall layers; bilayered specimens circumcavate to cornucavate. Endocyst occupies central part of pericyst; dorsoventral outline subcircular or oval with length greater than width. Endophragm smooth, 0.2-0.4 Ám thick. Periphragm smooth, often strongly crumpled; ca. 0.4 Ám thick around much of periphery of cyst, thins markedly and occasionally split apart along antapical margin. Zones of thinning often with an irregular outline and may extend along all or parts of antapical margin. On one specimen, the periphragm also seems to become thinner adjacent to apical horn (Plate 1, figs. 9, 10; Text-Figure 7A). This specimen also has a row of small spines less than 1 Ám high adjacent to base of right lateral horn. Parasulcal region often suggested on midventral surface by two longitudinal folds, which can extend over much of the cyst length.
Size. Pericyst length 84(102)116 Ám, width 71(86)118 Ám; 15 specimens measured. Endocyst length 44(52)66 Ám, 4 specimens measured; width 39 Ám, 1 specimen measured.
Comparison: Marshall 1989, p. 34
This species mainly differs from Limbicysta pediformis sp. nov. in having a bulbous hypocyst which lacks antapical horns, and either one or two wall layers. Although single-layered specimens are more common, frequent bilayered examples also occur.
Occurrence. Cook Cruise sample C4/87 21DDa.