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Surculosphaeridium vestitum
Surculosphaeridium? vestitum (Deflandre, 1939a, p.189–190, pl.11, figs.4–6) Davey et al., 1966, p.162. Emendation: Sarjeant, 1960b, p.397, as Baltisphaeridium vestitum.
Originally Hystrichosphaeridium, subsequently Baltisphaeridium (acritarch), thirdly Surculosphaeridium, fourthly (and now) Surculosphaeridium?, fifthly Multiplicisphaeridium? (acritarch), sixthly Systematophora. Stancliffe and Sarjeant (1990, p.207) questionably retained this taxon in Surculosphaeridium. Questionable assignment: Stover and Evitt (1978, p.83) and Fauconnier and Pourtoy in Fauconnier and Masure (2004, p.518).
Taxonomic junior synonym: Polystephanosphaera valensii, according to Courtinat (1989, p.173) — however, Stancliffe and Sarjeant (1990, p.209) retained Polystephanosphaera (as and now Systematophora) valensii.
Prior to re-examination of the holotype by Fauconnier and Pourtoy, Davey in Kennedy et al. (2000, p.638) indicated that this species should be assigned to Surculosphaeridium without question.
Holotype: Deflandre, 1939a, pl.11, fig.5; Fauconnier and Masure, 2004, pl.74, figs.11–12.
Age: Oxfordian
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REMARKS: Davey et al. 1966, p. 162-163
The holotype, from the Oxfordian of France, has been restudied by two of the authors (R.J.D. and W.A.S.S.), through the courtesy of Prof. Deflandre; and the specimens figured by Sarjeant (I962a) from the Oxfordian of England have also been re-examined in the light of recent studies. The processes of this species are extremely variable in form, so making the elucidation of the reflected tabulation very difficult. The processes are intratabular, the larger ones reflecting one plate of the original dinoflagellate theca, while some of the finer ones, in contrast, occur in twos and threes and represent a larger process which has been subdivided down to the surface of the central body. Thus two or three of these processes may reflect a single plate. The most distinctive and characteristic processes are the ones lying in the cingular zone. These are either deeply furcate or completely divided into two finer processes. Such cingular processes are especially characteristic of the genus Surculosphaeridillm, and make specimen orientation comparatively easy. The form of the processes and the exact distribution of the non-cingular processes, although difficult to determine, indicate that this species does belong to this genus.
MATERIAL (figured). Lower Oxfordian, Dorset, England. Upper Jurassic, England.
DIMENSIONS. Figured specimen: diameter of central body 37 by 47 µm, length of processes up to 30 µm.
Originally Hystrichosphaeridium, subsequently Baltisphaeridium (acritarch), thirdly Surculosphaeridium, fourthly (and now) Surculosphaeridium?, fifthly Multiplicisphaeridium? (acritarch), sixthly Systematophora. Stancliffe and Sarjeant (1990, p.207) questionably retained this taxon in Surculosphaeridium. Questionable assignment: Stover and Evitt (1978, p.83) and Fauconnier and Pourtoy in Fauconnier and Masure (2004, p.518).
Taxonomic junior synonym: Polystephanosphaera valensii, according to Courtinat (1989, p.173) — however, Stancliffe and Sarjeant (1990, p.209) retained Polystephanosphaera (as and now Systematophora) valensii.
Prior to re-examination of the holotype by Fauconnier and Pourtoy, Davey in Kennedy et al. (2000, p.638) indicated that this species should be assigned to Surculosphaeridium without question.
Holotype: Deflandre, 1939a, pl.11, fig.5; Fauconnier and Masure, 2004, pl.74, figs.11–12.
Age: Oxfordian
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REMARKS: Davey et al. 1966, p. 162-163
The holotype, from the Oxfordian of France, has been restudied by two of the authors (R.J.D. and W.A.S.S.), through the courtesy of Prof. Deflandre; and the specimens figured by Sarjeant (I962a) from the Oxfordian of England have also been re-examined in the light of recent studies. The processes of this species are extremely variable in form, so making the elucidation of the reflected tabulation very difficult. The processes are intratabular, the larger ones reflecting one plate of the original dinoflagellate theca, while some of the finer ones, in contrast, occur in twos and threes and represent a larger process which has been subdivided down to the surface of the central body. Thus two or three of these processes may reflect a single plate. The most distinctive and characteristic processes are the ones lying in the cingular zone. These are either deeply furcate or completely divided into two finer processes. Such cingular processes are especially characteristic of the genus Surculosphaeridillm, and make specimen orientation comparatively easy. The form of the processes and the exact distribution of the non-cingular processes, although difficult to determine, indicate that this species does belong to this genus.
MATERIAL (figured). Lower Oxfordian, Dorset, England. Upper Jurassic, England.
DIMENSIONS. Figured specimen: diameter of central body 37 by 47 µm, length of processes up to 30 µm.