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Surculosphaeridium trunculum
Surculosphaeridium trunculum Davey, 1979, p.559–560, pl.8, figs.6–9.
Holotype: Davey, 1979b, pl.8, fig.7; Fauconnier and Masure, 2004, pl.74, figs.8–10.
Locus typicus: DSDP Leg 48. Hole 402A, northern Bay of Biscay, North Atlantic
Stratum typicum: Apto-Albian,
Age: Aptian-Albian
Original diagnosis: Davey 1979b, p. 559-560
A smooth walled, subspherical speeies of Surculosphaeridium possessing one, or more rarely two, solid processes per paraplate. The wider proeesses, whieh oeeupy the pre-, postcingular, antapical regions, typically have a proximal bifureation giving the processes a basal subconical perforation. Often, particularly in the paracingular region, the processes may be deeply furcate or a single paracingular process may be represented by two finer processes: sometimes these latter processes are joined by a medial bar. Distally the processes fork irregularly. An archeopyle is usually developed.
Dimensions: HolotypeRange
Endocyst diameter 32 x 39 Ám26 (35) 44 Ám
Process length 11-16 Ám10 (15) 20 Ám
Original description: Davey 1979b, p. 559-560
The processes vary considerably in width with the widest processes occupying the pre-, postcingular, and antapical regions; parasulcal processes are the thinnest. The apical and paracingular processes are intermediate in size. As in other species of Surculosphaeridium the paracingular processes may be furcate, sometimes deeply so, and, when this furcation extends to the cyst wall, the paracingular plate then bears two processes. Distally the processes typically birfucate or trifurcate and terminate with a small birfucation or spinelets.
Remarks: Davey 1979b, p. 559-560
Superficially S. trunculum sp. nov. is most similar to S. longifurcatum (Firtion, 1952) Davey et al., 1966, and is probably ancestral to it. S. trunculum has to date only been recorded from the Aptian and S. longifurcatum has a known first stratigraphic occurrence in the basal middle Albian (see Davey and Verdier, 1971). Neither species has so far been recorded from the lower Albian. S". trl/nculum differs from S. longifurcatum by the possession of two very distinctive process types. Firstly are the type that birfurcate proximally having a subconical basal perforation, and secondly are the thinner processes, usually paracingular, that are linked by a medial bar. Some of the processes of Systematophora complicata Neale and Sarjeant, 1962, have a similar medial linkage but are considerably more complex. S. complicata as illustrated by Duxbury (1977; pl. 7, fig. 8) may be identical to S. truncullum.
Holotype: Davey, 1979b, pl.8, fig.7; Fauconnier and Masure, 2004, pl.74, figs.8–10.
Locus typicus: DSDP Leg 48. Hole 402A, northern Bay of Biscay, North Atlantic
Stratum typicum: Apto-Albian,
Age: Aptian-Albian
Original diagnosis: Davey 1979b, p. 559-560
A smooth walled, subspherical speeies of Surculosphaeridium possessing one, or more rarely two, solid processes per paraplate. The wider proeesses, whieh oeeupy the pre-, postcingular, antapical regions, typically have a proximal bifureation giving the processes a basal subconical perforation. Often, particularly in the paracingular region, the processes may be deeply furcate or a single paracingular process may be represented by two finer processes: sometimes these latter processes are joined by a medial bar. Distally the processes fork irregularly. An archeopyle is usually developed.
Dimensions: HolotypeRange
Endocyst diameter 32 x 39 Ám26 (35) 44 Ám
Process length 11-16 Ám10 (15) 20 Ám
Original description: Davey 1979b, p. 559-560
The processes vary considerably in width with the widest processes occupying the pre-, postcingular, and antapical regions; parasulcal processes are the thinnest. The apical and paracingular processes are intermediate in size. As in other species of Surculosphaeridium the paracingular processes may be furcate, sometimes deeply so, and, when this furcation extends to the cyst wall, the paracingular plate then bears two processes. Distally the processes typically birfucate or trifurcate and terminate with a small birfucation or spinelets.
Remarks: Davey 1979b, p. 559-560
Superficially S. trunculum sp. nov. is most similar to S. longifurcatum (Firtion, 1952) Davey et al., 1966, and is probably ancestral to it. S. trunculum has to date only been recorded from the Aptian and S. longifurcatum has a known first stratigraphic occurrence in the basal middle Albian (see Davey and Verdier, 1971). Neither species has so far been recorded from the lower Albian. S". trl/nculum differs from S. longifurcatum by the possession of two very distinctive process types. Firstly are the type that birfurcate proximally having a subconical basal perforation, and secondly are the thinner processes, usually paracingular, that are linked by a medial bar. Some of the processes of Systematophora complicata Neale and Sarjeant, 1962, have a similar medial linkage but are considerably more complex. S. complicata as illustrated by Duxbury (1977; pl. 7, fig. 8) may be identical to S. truncullum.