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Leipokatium invisitatum
Leipokatium invisitatum Bradford, 1975
Holotype: Bradford 1975: fig. 8
Locus typicus: Dawhat Shishah, east coast of the Musandam Peninsula, Oman.
Stratum typicum: recent sediments
Age: Recent
Original diagnosis: Bradford 1975, p. 3067
Epitract much larger than hypotract domed or conical with or without an apical horn or apical walMhickening. Cingulum broad equatorially but with no width: hypotract very small, usually dorsoventrally flattened, with or without antapical horns. Polar view circular to reniform with small sulcal depression. Wall thin, usually smooth or lightly ornamented. Anterior intercalary archeopyle. Acapsulate.
Dimensions: holotype: length 56 Ám, lateral breadth 73 Á. Archeopyle height 15 Ám, archeopyle breadth 27 Ám, length of antapical horns 21 Ám, distance between antapical horns (distally) 22 Ám; other specimens, length 31-56 Ám, lateral breadth 37-80 Ám, dorsoventral breadth 45 Ám (only one specimen measured), archeopyle height 9-15 Ám, archeopyle breadth 14-27 Ám, length of antapical horns 10-21 Ám. Distance between antapical horns (distally) 10-30 Ám. Number of specimens measured 10.
Description: Bradford 1975, p. 3067
Peridinioid cyst with epitract and hypotract of very unequal sizes. The epitract usually domed, although sometimes conical, but always with convex sides. The cysts can possess a small apical horn or, more commonly, have a slight wall thickening apically. No true cingulum, but represented by a line on the surface of the epitract at the broadest point of the phragma. The hypotract is very small and dorsoventrally flattened. Wall thickening is present at the distal edges or at the distal tips of the two small antapical processes. The whole hypotract is elongate in a lateral direction. The antapical depression varies from being shallow to being moderately deep. In polar view, the cysts are circular to reniform in outline, being slightly more elongate laterally. A distinct sulcal depression is always present on the ventral surface. The wall is thin, often smooth but can have a slightly shagreenate ornamentation. The archeopyle is moderately large, anterior, dorsally positioned, and probably reflects at least one intercalary plate.
Remark: Only one species belonging to this genus has been recogni7ed. This form differs from those described under the genus Omanodinium nov. that it possesses a very small and distinctive hypotract.
Thecal affinity: Unknown; but cysts are thought to have peridinioid characters.
Occurrence: Rare. This species occurs in sample 22, which is situated to the front of the Tigris-Euphrates delta system; in sample 205 from the Northern Arabian Sea; and in six samples to the eastern side of the Musandam Peninsula.
Holotype: Bradford 1975: fig. 8
Locus typicus: Dawhat Shishah, east coast of the Musandam Peninsula, Oman.
Stratum typicum: recent sediments
Age: Recent
Original diagnosis: Bradford 1975, p. 3067
Epitract much larger than hypotract domed or conical with or without an apical horn or apical walMhickening. Cingulum broad equatorially but with no width: hypotract very small, usually dorsoventrally flattened, with or without antapical horns. Polar view circular to reniform with small sulcal depression. Wall thin, usually smooth or lightly ornamented. Anterior intercalary archeopyle. Acapsulate.
Dimensions: holotype: length 56 Ám, lateral breadth 73 Á. Archeopyle height 15 Ám, archeopyle breadth 27 Ám, length of antapical horns 21 Ám, distance between antapical horns (distally) 22 Ám; other specimens, length 31-56 Ám, lateral breadth 37-80 Ám, dorsoventral breadth 45 Ám (only one specimen measured), archeopyle height 9-15 Ám, archeopyle breadth 14-27 Ám, length of antapical horns 10-21 Ám. Distance between antapical horns (distally) 10-30 Ám. Number of specimens measured 10.
Description: Bradford 1975, p. 3067
Peridinioid cyst with epitract and hypotract of very unequal sizes. The epitract usually domed, although sometimes conical, but always with convex sides. The cysts can possess a small apical horn or, more commonly, have a slight wall thickening apically. No true cingulum, but represented by a line on the surface of the epitract at the broadest point of the phragma. The hypotract is very small and dorsoventrally flattened. Wall thickening is present at the distal edges or at the distal tips of the two small antapical processes. The whole hypotract is elongate in a lateral direction. The antapical depression varies from being shallow to being moderately deep. In polar view, the cysts are circular to reniform in outline, being slightly more elongate laterally. A distinct sulcal depression is always present on the ventral surface. The wall is thin, often smooth but can have a slightly shagreenate ornamentation. The archeopyle is moderately large, anterior, dorsally positioned, and probably reflects at least one intercalary plate.
Remark: Only one species belonging to this genus has been recogni7ed. This form differs from those described under the genus Omanodinium nov. that it possesses a very small and distinctive hypotract.
Thecal affinity: Unknown; but cysts are thought to have peridinioid characters.
Occurrence: Rare. This species occurs in sample 22, which is situated to the front of the Tigris-Euphrates delta system; in sample 205 from the Northern Arabian Sea; and in six samples to the eastern side of the Musandam Peninsula.