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Phthanoperidinium indistinctum
Phthanoperidinium indistinctum Islam, 1982
Holotype: Islam, 1982, pl.2, fig.1
Locus typicus: Isle of Sheppey, southeast England
Stratum typicum: London Clay, Division E, Early(middle?) Eocene
Original diagnosis: Islam, 1982, p.311
The cyst possesses an ellipsoidal shape, longish or roundish, with a short apical horn and sometimes an antapical lobe; composed of periphragm and endophragm very closely adpressed together, both phragma are very thin, periphragm chagrinate; proximate; acavate; periphragmal folding and partial thickening define the paracingulum and an incomplete paratabulation; paratabulation as deduced by observing a large number of specimens is 4", 3a, 7", 6c, 5""", 2"""", xs; paracingulum helicoidal and may be slightly depressed; parasulcus may be indicated by slight depression; archeopyle when present is intercalary type I(2a); a few very fine and very short fibrils here and there, particularly at some gonal points, may occur. Dimensions: Holotype: pericyst 45 X 35 µm, length of apical horn 3 µm. Range: pericyst length 46(40)34 µm, breadth 36(32)26 µm, length of apical horn 3--5 µm. Specimens measured 10.
Affinities:
Islam, 1982, p.311: The species somewhat resembles P. resistente (Morgenroth) but has a thinner periphragm having folds but few thickenings, occasional fibrils and no antapical lobe/horn. The two species, however, seem related to each other.
Holotype: Islam, 1982, pl.2, fig.1
Locus typicus: Isle of Sheppey, southeast England
Stratum typicum: London Clay, Division E, Early(middle?) Eocene
Original diagnosis: Islam, 1982, p.311
The cyst possesses an ellipsoidal shape, longish or roundish, with a short apical horn and sometimes an antapical lobe; composed of periphragm and endophragm very closely adpressed together, both phragma are very thin, periphragm chagrinate; proximate; acavate; periphragmal folding and partial thickening define the paracingulum and an incomplete paratabulation; paratabulation as deduced by observing a large number of specimens is 4", 3a, 7", 6c, 5""", 2"""", xs; paracingulum helicoidal and may be slightly depressed; parasulcus may be indicated by slight depression; archeopyle when present is intercalary type I(2a); a few very fine and very short fibrils here and there, particularly at some gonal points, may occur. Dimensions: Holotype: pericyst 45 X 35 µm, length of apical horn 3 µm. Range: pericyst length 46(40)34 µm, breadth 36(32)26 µm, length of apical horn 3--5 µm. Specimens measured 10.
Affinities:
Islam, 1982, p.311: The species somewhat resembles P. resistente (Morgenroth) but has a thinner periphragm having folds but few thickenings, occasional fibrils and no antapical lobe/horn. The two species, however, seem related to each other.