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Luxadinium lingulatum
Luxadinium lingulatum Marshall, 1989
Holotype. Marshall 1989: Plate 9, figs. 1-3.
Locus typicus: Gipsland Basin, Southern Australia
Stratum typicum: Late Cretaceous
Age: Turonian-Early Santonian
Description: Marshall 1989, p. 52: Luxadinium lingulatum
Cysts compressed dorsoventrally with a weak middorsal bulge. Apex bears a weak to pronounced subconical horn with a thickened, truncate tip. Antapex modified by two weak horns forming rounded bulges or subconical projections. Cysts bilayered near apex with pericoel restricted to beneath apical horn; both layers 0.2-0.4,um thick. Only one wall layer discernible over remainder of cyst, surface smooth, often strongly folded, ornamented by frequent to common, rounded grana and baculae up to 2 llm high: sculpture irregularly distributed. Paracingulum marked by two rounded lateral ridges 7-10 Ám apart; ridges separated by a shallow groove. Parasulcal area defined by a shallow longitudinal groove on midventral surface, frequently containing a small thickened ridge representing a possible flagellar marking. Archeopyle rarely type (313P); usually incompletely indicated by sutures on dorsal surface of epicyst in the area of paraplates 1-3a.
Size. Pericyst length 65(74)831lm, width 59(68)76 Ám; 13 specimens measured.
Discussion. A type (313P) archeopyle was only rarely observed, and most specimens examined have only an incomplete arrangement of sutures in the area of paraplates 1-3a.
Comparison. This species is characterized by the presence of two layers near the apex, the thickened tip on the apical horn, and the scattered grana and baculae on the cyst surface. It resembles Luxadinium primulum Brideaux & Mclntyre 1975 from the middle Albian of the District of Mackenzie, Northwest Territories, Canada (Brideaux and Mclntyre, 1975, p.37, pl. 12, figs. 9-12, pl. 13, figs. 1-8), but difers in lacking intratabular apiculae on the endophragm.
Holotype. Marshall 1989: Plate 9, figs. 1-3.
Locus typicus: Gipsland Basin, Southern Australia
Stratum typicum: Late Cretaceous
Age: Turonian-Early Santonian
Description: Marshall 1989, p. 52: Luxadinium lingulatum
Cysts compressed dorsoventrally with a weak middorsal bulge. Apex bears a weak to pronounced subconical horn with a thickened, truncate tip. Antapex modified by two weak horns forming rounded bulges or subconical projections. Cysts bilayered near apex with pericoel restricted to beneath apical horn; both layers 0.2-0.4,um thick. Only one wall layer discernible over remainder of cyst, surface smooth, often strongly folded, ornamented by frequent to common, rounded grana and baculae up to 2 llm high: sculpture irregularly distributed. Paracingulum marked by two rounded lateral ridges 7-10 Ám apart; ridges separated by a shallow groove. Parasulcal area defined by a shallow longitudinal groove on midventral surface, frequently containing a small thickened ridge representing a possible flagellar marking. Archeopyle rarely type (313P); usually incompletely indicated by sutures on dorsal surface of epicyst in the area of paraplates 1-3a.
Size. Pericyst length 65(74)831lm, width 59(68)76 Ám; 13 specimens measured.
Discussion. A type (313P) archeopyle was only rarely observed, and most specimens examined have only an incomplete arrangement of sutures in the area of paraplates 1-3a.
Comparison. This species is characterized by the presence of two layers near the apex, the thickened tip on the apical horn, and the scattered grana and baculae on the cyst surface. It resembles Luxadinium primulum Brideaux & Mclntyre 1975 from the middle Albian of the District of Mackenzie, Northwest Territories, Canada (Brideaux and Mclntyre, 1975, p.37, pl. 12, figs. 9-12, pl. 13, figs. 1-8), but difers in lacking intratabular apiculae on the endophragm.