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Pilosidinium assymetrum
Pilosidinium asymmetrum (Fenton et al., 1980, p.160,162, pl.16, figs.1,3,5) Courtinat in Fauconnier and Masure, 2004, p.447.
Holotype: Fenton et al., 1980, pl.16, fig.3. Originally Tenua Eisenack, subsequently Sentusidinium, thirdly (and now) Pilosidinium. Age: late Bajocian–early Bathonian.
Orignal diagnosis: Fenton et al., 1980, p. 160: Tenua asymmetra
Proximate, non-tabulate cyst, rounded to ovoidal outline. Wall thin, ornamented with rugulae, granules, spines, baculae, and briefly bifurcate processes concentrated at the antapical pole, becoming reduced or absent towards the apex. Paracingulum and parasulcus absent or indistinct, defined by reduction or absence of ornament. Archaeopyle apical in development with accessory parasutures defining six precingular paraplates.
Original description: Fenton et al., 1980, p. 160: Tenua asymmetra
The outline of the cyst is variable, as the thin wall (< 0.5 µm) is prone to breakage along the accessory archaeopyle parasutures. This feature exaggerates the width and facilitates easy folding of the cyst.
At the antapical pole the ornament consists of irregularly distributed rugulae, granules, blunt or pointed spines, baculae, and briefly bifurcate processes, all under 2 µm in height. The surface is coarsely scabrate, becoming faintly scabrate or occasionally smooth anterior to the coarsely ornamented antapex. The diverse ornamentation is also reduced in size and density anterior to the antapical pole. When the ornament is totally absent, often due to corrosion, the autophragm takes on an infra-vermiculate appearance. When present, the paracingulum varies between 3 and 6 µm in width. Dimensions. Cyst width--60(74)94 µm (18 specimens measured), length--57(68)80 µm; holotype width-60 µm, length--58 µm.
Holotype: Fenton et al., 1980, pl.16, fig.3. Originally Tenua Eisenack, subsequently Sentusidinium, thirdly (and now) Pilosidinium. Age: late Bajocian–early Bathonian.
Orignal diagnosis: Fenton et al., 1980, p. 160: Tenua asymmetra
Proximate, non-tabulate cyst, rounded to ovoidal outline. Wall thin, ornamented with rugulae, granules, spines, baculae, and briefly bifurcate processes concentrated at the antapical pole, becoming reduced or absent towards the apex. Paracingulum and parasulcus absent or indistinct, defined by reduction or absence of ornament. Archaeopyle apical in development with accessory parasutures defining six precingular paraplates.
Original description: Fenton et al., 1980, p. 160: Tenua asymmetra
The outline of the cyst is variable, as the thin wall (< 0.5 µm) is prone to breakage along the accessory archaeopyle parasutures. This feature exaggerates the width and facilitates easy folding of the cyst.
At the antapical pole the ornament consists of irregularly distributed rugulae, granules, blunt or pointed spines, baculae, and briefly bifurcate processes, all under 2 µm in height. The surface is coarsely scabrate, becoming faintly scabrate or occasionally smooth anterior to the coarsely ornamented antapex. The diverse ornamentation is also reduced in size and density anterior to the antapical pole. When the ornament is totally absent, often due to corrosion, the autophragm takes on an infra-vermiculate appearance. When present, the paracingulum varies between 3 and 6 µm in width. Dimensions. Cyst width--60(74)94 µm (18 specimens measured), length--57(68)80 µm; holotype width-60 µm, length--58 µm.