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Exochosphaeridium brevitruncatum
From Fensome et al., 2019:
Exochosphaeridium brevitruncatum Slimani, 1994, p.72–73, pl.12, figs.15–19. Holotype: Slimani, 1994, pl.12, figs.15–17. Age: early Campanian–late Maastrichtian.
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Original description Slimani, 1994 translation PKB 2025
Name derivation: Latin: brew, short; truncatus, truncated; reference to the short and truncated processes.
Holiday: Halembaye, sample 57, preparation 5, E.F. coord. Z39.
Type locality: Halembaye sample 57.
Type horizon: Upper Maastrichtian (Lixhel Member).
Synonymy: 71975: Exochosphaeridium sp. - DAVEY, p. 151, pl. 1, fig. 3.
Diagnosis: Intermediate-sized Excochosphaeridium cyst with an oval to subcircular outline. The thick autophragm is thinly spongy and bears numerous non-tabular processes that are solid, extremely short, truncated distally, and occasionally joined proximally. A distinct apical process is always present.
Dimensions:
Holotype: Entire cyst, length: 54 µm, width: 48 µm.
Variations: Central body, length: 40-60 µm, width: 36-50 µm.
Process length: 2(4)6 µm.
Number of specimens measured: 15.
Material: > 30 specimens.
Description:
The thin, smooth endophragm is attached to a very thick (approximately 4 µm) and finely spongy periphragm. The processes are 3 µm wide on average and distally truncated, with tips rarely provided with fine denticles. They are isolated or rarely joined at their bases in groups of 2 to 3 processes; their distribution is intratabular and more or less regular, with a rare alignment of processes indicating the paracingulum. The apical process (7 to 8 µm long) is distinct, solid, often branched, and allows for orientation of the cyst. The archaeopyle is precingulate, type P (3") with a pentagonal outline. The operculum consists of a single free precingulate paraplate.
Note: This species is characterized mainly by its very short processes. At low magnification, the cyst shows a tubercular appearance. The processes are comparable in size to the processes of several species of the genus Trichodinium EISENACK and COOKSON (1960) emend. CLARKE and VERDIER (1967); but they are broader, robust, and much less densely distributed. The latter genus is more densely ornamented with fine processes; it is therefore preferable to assign our species to the genus Exochosphaeridium.
Comparison:
Exochosphaeridium brevitruncatum sp. nov. is similar to the specimen of Exochosphaeridium sp. figured by DAVEY (1975: p. 151, pl. 1, fig. 3) and which this author described as follows: "in one specimen the processes are extremely reduced and are of tubercular dimensions" with a length of 2 to 4 pm, also found in the Senonian and probably in the Campanian of Ghana (Africa). E. brevispinosum MATSUOKA. (1984a), from the Middle Eocene, also has short processes but is distinguished from the present species mainly by the highly fibrous appearance of the processes.
Stratigraphic distribution: Beutenaken: samples 1 to 5, Halembaye: samples 1 to 80; Lower Campanian - Upper Maastrichtian. (G. quadrata Zone - B. junior Zone). Turnhout: -940 to -807.90 m, Upper Campanian - Upper Maastrichtian.
Exochosphaeridium brevitruncatum Slimani, 1994, p.72–73, pl.12, figs.15–19. Holotype: Slimani, 1994, pl.12, figs.15–17. Age: early Campanian–late Maastrichtian.
---------------------------------------------------------------------------------------------------
Original description Slimani, 1994 translation PKB 2025
Name derivation: Latin: brew, short; truncatus, truncated; reference to the short and truncated processes.
Holiday: Halembaye, sample 57, preparation 5, E.F. coord. Z39.
Type locality: Halembaye sample 57.
Type horizon: Upper Maastrichtian (Lixhel Member).
Synonymy: 71975: Exochosphaeridium sp. - DAVEY, p. 151, pl. 1, fig. 3.
Diagnosis: Intermediate-sized Excochosphaeridium cyst with an oval to subcircular outline. The thick autophragm is thinly spongy and bears numerous non-tabular processes that are solid, extremely short, truncated distally, and occasionally joined proximally. A distinct apical process is always present.
Dimensions:
Holotype: Entire cyst, length: 54 µm, width: 48 µm.
Variations: Central body, length: 40-60 µm, width: 36-50 µm.
Process length: 2(4)6 µm.
Number of specimens measured: 15.
Material: > 30 specimens.
Description:
The thin, smooth endophragm is attached to a very thick (approximately 4 µm) and finely spongy periphragm. The processes are 3 µm wide on average and distally truncated, with tips rarely provided with fine denticles. They are isolated or rarely joined at their bases in groups of 2 to 3 processes; their distribution is intratabular and more or less regular, with a rare alignment of processes indicating the paracingulum. The apical process (7 to 8 µm long) is distinct, solid, often branched, and allows for orientation of the cyst. The archaeopyle is precingulate, type P (3") with a pentagonal outline. The operculum consists of a single free precingulate paraplate.
Note: This species is characterized mainly by its very short processes. At low magnification, the cyst shows a tubercular appearance. The processes are comparable in size to the processes of several species of the genus Trichodinium EISENACK and COOKSON (1960) emend. CLARKE and VERDIER (1967); but they are broader, robust, and much less densely distributed. The latter genus is more densely ornamented with fine processes; it is therefore preferable to assign our species to the genus Exochosphaeridium.
Comparison:
Exochosphaeridium brevitruncatum sp. nov. is similar to the specimen of Exochosphaeridium sp. figured by DAVEY (1975: p. 151, pl. 1, fig. 3) and which this author described as follows: "in one specimen the processes are extremely reduced and are of tubercular dimensions" with a length of 2 to 4 pm, also found in the Senonian and probably in the Campanian of Ghana (Africa). E. brevispinosum MATSUOKA. (1984a), from the Middle Eocene, also has short processes but is distinguished from the present species mainly by the highly fibrous appearance of the processes.
Stratigraphic distribution: Beutenaken: samples 1 to 5, Halembaye: samples 1 to 80; Lower Campanian - Upper Maastrichtian. (G. quadrata Zone - B. junior Zone). Turnhout: -940 to -807.90 m, Upper Campanian - Upper Maastrichtian.