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Phthanoperidinium chalossense
Phthanoperidinium chalossense Michoux, 1985
Holotype: Michoux, 1985, pl.3, figs.6-8
Age: Middle Eocene
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Original description: [Michoux, 1985] (translated from French):
Phthanoperidinium chalossensis n. sp.
(PI. 3, fig. 6-8, 15)
Holotype: Slide N2a-4, coordinates P4-4.
Name origin: From Chalosse, a region of western Aquitaine where the dinocysts described here come from.
Type locality: Nousse, marl-limestone from the base of the Nousse beds.
Diagnosis: Proximate peridinioid cyst, lozenge-shaped to pentagonal in outline. Paratabulation indicated by parasutural ridges joining at the apex to form a tall, massive rectangular horn. Intercalary archaeopyle type 3 I (1a-3a) formed by the loss of the three intercalary paraplates.
Description: Proximate, peridinioid cyst, lozenge-shaped to pentagonal in shape. Ovoid endophragm. The periphragm forms the parasutural elements, consisting of individual narrow blades or continuous ridges notched distally. The apical horn is tall and wide, its distal end is truncated and narrower than its base. The pre- and postcingulate paraplates are diamond-shaped, except for the 4" paraplate, which is almost square. The antapical portion of the cyst is decorated with a continuous ridge, rather than two individual horns. In addition to the septa, the periphragm is decorated with small spines or warts, visible on SEM (PI. 3, Fig. 15).
The archaeopyle is formed by the loss of the three intercalary paraplates. Its lateral angles are rounded.
The tabulation reflected by the parasutural ridges is that of the genus Phthanoperidinium: 4' 3 a, 7", 5'", 2"".
Dimensions: Height: 65 to 70 μm; width: 48 to 55 μm; 3 specimens measured.
Discussion: This species differs from P. delicatum and P. crenulatum by its larger size and its distinctly rhomboidal, its more massive septa, and the outline of the posterior edge of the archaeopyle which presents a clear detachment at the level of the connection between paraplates 2a and 4" (ct. Pl. 3, fig. 7 and 15).
P. schizokeras is also rhomboidal but differs by its divided apical horn.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP
Phthanoperidinium chalossense Michoux, 1985. Phthanoperidinium chalossense has the paratabulation indicated by parasutural crests and a very prominent, rectangular, high, solid horn. The archeopyle is 3I, formed from the loss of three plates. The crests are often broken so that there are distinct processes which are oblate or bifid distally and there are intratabular granules or spinules. The antapex is rounded. Size: height 65-70 µm, width 48-55 µm.
Holotype: Michoux, 1985, pl.3, figs.6-8
Age: Middle Eocene
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Original description: [Michoux, 1985] (translated from French):
Phthanoperidinium chalossensis n. sp.
(PI. 3, fig. 6-8, 15)
Holotype: Slide N2a-4, coordinates P4-4.
Name origin: From Chalosse, a region of western Aquitaine where the dinocysts described here come from.
Type locality: Nousse, marl-limestone from the base of the Nousse beds.
Diagnosis: Proximate peridinioid cyst, lozenge-shaped to pentagonal in outline. Paratabulation indicated by parasutural ridges joining at the apex to form a tall, massive rectangular horn. Intercalary archaeopyle type 3 I (1a-3a) formed by the loss of the three intercalary paraplates.
Description: Proximate, peridinioid cyst, lozenge-shaped to pentagonal in shape. Ovoid endophragm. The periphragm forms the parasutural elements, consisting of individual narrow blades or continuous ridges notched distally. The apical horn is tall and wide, its distal end is truncated and narrower than its base. The pre- and postcingulate paraplates are diamond-shaped, except for the 4" paraplate, which is almost square. The antapical portion of the cyst is decorated with a continuous ridge, rather than two individual horns. In addition to the septa, the periphragm is decorated with small spines or warts, visible on SEM (PI. 3, Fig. 15).
The archaeopyle is formed by the loss of the three intercalary paraplates. Its lateral angles are rounded.
The tabulation reflected by the parasutural ridges is that of the genus Phthanoperidinium: 4' 3 a, 7", 5'", 2"".
Dimensions: Height: 65 to 70 μm; width: 48 to 55 μm; 3 specimens measured.
Discussion: This species differs from P. delicatum and P. crenulatum by its larger size and its distinctly rhomboidal, its more massive septa, and the outline of the posterior edge of the archaeopyle which presents a clear detachment at the level of the connection between paraplates 2a and 4" (ct. Pl. 3, fig. 7 and 15).
P. schizokeras is also rhomboidal but differs by its divided apical horn.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP
Phthanoperidinium chalossense Michoux, 1985. Phthanoperidinium chalossense has the paratabulation indicated by parasutural crests and a very prominent, rectangular, high, solid horn. The archeopyle is 3I, formed from the loss of three plates. The crests are often broken so that there are distinct processes which are oblate or bifid distally and there are intratabular granules or spinules. The antapex is rounded. Size: height 65-70 µm, width 48-55 µm.