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Charlesdowniea clathrata ssp. angulosa
Charlesdowniea clathrata ssp. angulosa, (Chateauneuf and Gruas-Cavagnetto, 1978), Lentin and Vozzhennikova, 1989
Originally Kisselevia clathrata subsp. angulosa, subsequently Charlesdowniea? clathrata subsp. angulosa, thirdly (and now) Talladinium? angulosum.
Holotype: Chateauneuf and Gruas-Cavagnetto 1978, pl.5, fig.8-9
Locus typicus: Quarry at Cormeilles-en-Parisis, Paris Basin, France
Stratum typicum: Early Oligocene (Sannoisian)
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Original description as Kisselevia clathrata ssp. angulosa: [Chateauneuf and Gruas-Cavagnetto 1978, p. 69-70]: (Translation: LPP)
Diagnosis:
Subspecies of Kisselovia clathrata, characterized by its very particular form: epitract sharply triangular with straight or concave sides. Hypotract subpolygonal, deformed by the more or less substantial reduction of the right antapical horn. Apical horn well-developed with a very sharp tip, rarely truncate (but often snapped). Antapical horns symmetrical to slightly asymmetrical resulting from the reduction of the right one. Lateral horns often drawn out and very sharply accentuated by the cingular zone.
The endophragm in narrow contact with the periphragm, it has a clearly pentagonal form with rounded angles.
The processes are straight (5 to 10 µm) in the pre- and postcingular zone, longer near the horns. They are intratabular and often aligned in series within the plates. The distal part of the processes is fused with a finely perforate membrane "simulating" perfectly the form of the plates. This membrane sometimes gives the impression of a very dense, quasi-continuous network.
Precingular (sic) archaeopyle, very rounded pentagonal or rectangular, the operculum very often in place.
Remark (LPP):
The archaeopyle is, of course, intercalary.
Dimensions:
Holotype: 132/130 µm, central body 110/112 µm. Processes 85 (sic, should be 5?) to 8 µm.
Affinities:
Kisselevia clathrata ssp. angulosa differs very clearly from the type species clathrata, described by Eisenack from the phosphorites of Samland, in its clearly more angular outline with straight or even convex sides, in a less developed pericoel and finally in the details of the processes, compared to those of Kisselevia clathrata. These processes, arranged in series, form, by the anastomosing of their distal ends, a characteristical network in the form of a balustrade like in Kisselevia clathrata, visible along the outline of the periphragm. The diagnosis of Eisenack is not accurate for the description of the plates and the position of the processes, except that the fields are delimited by series of processes. The study, under high magnification, of the distal surface of the processes shows that they are arranged in series within each plate, the outline of each plate being delimited by a continuous series of processes. The distal ends are fused within each complex by a thin membrane, continuous at the level of each plate, formed by a network of of very thin and dense filaments.
Originally Kisselevia clathrata subsp. angulosa, subsequently Charlesdowniea? clathrata subsp. angulosa, thirdly (and now) Talladinium? angulosum.
Holotype: Chateauneuf and Gruas-Cavagnetto 1978, pl.5, fig.8-9
Locus typicus: Quarry at Cormeilles-en-Parisis, Paris Basin, France
Stratum typicum: Early Oligocene (Sannoisian)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Kisselevia clathrata ssp. angulosa: [Chateauneuf and Gruas-Cavagnetto 1978, p. 69-70]: (Translation: LPP)
Diagnosis:
Subspecies of Kisselovia clathrata, characterized by its very particular form: epitract sharply triangular with straight or concave sides. Hypotract subpolygonal, deformed by the more or less substantial reduction of the right antapical horn. Apical horn well-developed with a very sharp tip, rarely truncate (but often snapped). Antapical horns symmetrical to slightly asymmetrical resulting from the reduction of the right one. Lateral horns often drawn out and very sharply accentuated by the cingular zone.
The endophragm in narrow contact with the periphragm, it has a clearly pentagonal form with rounded angles.
The processes are straight (5 to 10 µm) in the pre- and postcingular zone, longer near the horns. They are intratabular and often aligned in series within the plates. The distal part of the processes is fused with a finely perforate membrane "simulating" perfectly the form of the plates. This membrane sometimes gives the impression of a very dense, quasi-continuous network.
Precingular (sic) archaeopyle, very rounded pentagonal or rectangular, the operculum very often in place.
Remark (LPP):
The archaeopyle is, of course, intercalary.
Dimensions:
Holotype: 132/130 µm, central body 110/112 µm. Processes 85 (sic, should be 5?) to 8 µm.
Affinities:
Kisselevia clathrata ssp. angulosa differs very clearly from the type species clathrata, described by Eisenack from the phosphorites of Samland, in its clearly more angular outline with straight or even convex sides, in a less developed pericoel and finally in the details of the processes, compared to those of Kisselevia clathrata. These processes, arranged in series, form, by the anastomosing of their distal ends, a characteristical network in the form of a balustrade like in Kisselevia clathrata, visible along the outline of the periphragm. The diagnosis of Eisenack is not accurate for the description of the plates and the position of the processes, except that the fields are delimited by series of processes. The study, under high magnification, of the distal surface of the processes shows that they are arranged in series within each plate, the outline of each plate being delimited by a continuous series of processes. The distal ends are fused within each complex by a thin membrane, continuous at the level of each plate, formed by a network of of very thin and dense filaments.