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Enneadocysta robusta
Enneadocysta robusta Stover and Williams, 1995
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Stover and Williams, 1995, p. 115
Plate 7, Figures 1a-c; text-figure 1, no. K
- Areosphaeridium arcuatum Eaton 1971, pl. 3, fig. 4, not figs. 1-3, 5-9 [not pl. 3, fig. 1 which is the holotype of Enneadocysta (as Areosphaeridium) arcuata].
Description:
Shape: Cysts skolochorate with subspherical to ellipsoidal central body and with slightly offset parasulcal notch.
Wall relationships: Autophragm only.
Wall features: Autophragm smooth or coarsely pitted, with 18 intratabular processes, nine on epicyst and nine on hypocyst; paracingular processes absent. Processes short, relative to body diameter, similar in length but variable in width; generally markedly expanded distally with recurved, branched, buccinate or licrate terminations. Arcuations of licrate structures tend to be short and shallow, and the branched or buccinate ends may be spinulate or irregularly perforate. Open ends of licrite structures on the two opposed antapical processes face each other medially.
Excystrnent type: Archeopyle apical; although isolated opercula have not been observed. Based on body shapes, some opercula may be slightly longer transversely than dorso-ventrally.
Paratabulation: Expressed on epicyst by principal and accessory archeopyle sutures and positions of intratabular processes; on hypocyst by process locations only. Process formula: ?4", 6"", 0c, 6""", 2"""", 1ps; anterior margin of paraplate 6"" peaked asymmetrically, left side shorter than right. This paraplate lacks a process and is slightly narrower than paraplate 1"". Configuration of hypocystal processes partiform.
Paracingulum: Delineated by absence of processes.
Parasulcus: Limits of parasulcus expressed anteriorly by parasulcal notch and posteriorly by posterior parasulcal process.
Size: Intermediate; body diameter 50 Ám to 62 Ám, overall diameter 67 Ám to 85 Ám, process length 10 Ám to 15 Ám, process width at midlength 2.5 Ám to 8.0 Ám; wider processes usually restricted to dorsal and lateral surfaces.
Comments
Enneadocysta robusta does not have processes on the sixth precingular paraplate (pl. 7, fig. 1c) or on any of the cingular paraplates (pl. 7, figs. 1a-c).
Holotype:
Specimen illustrated in Plate 7, Figures 1a-c. Location: EPR slide 2753V-R, coordinates R04.8+19.8, Exxon Production Co., Research Center, Houston, Texas, U.S.A.
Type locality and stratum:
Locality: Belgium Basin, Assenede Well at coordinates 107.614/215.180, Belgium.
Stratum: Core sample 21 at 71.40 meters (lower Middle Eocene, Lutetian).
Stratigraphic and geographic data:
Early Mid Eocene (Lutetian). The species is known from strata within the 44 Ma depositional sequence only.
Enneadocysta robusta is recorded solely from Northern Hemisphere localities in Belgium and England. These are: Belgian Basin, Assenede Well (lower Middle Eocene) and the Hampshire Basin, southern England, Isle of Wight, Whitecliff Bay section (lower Middle Eocene).
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Stover and Williams, 1995, p. 115
Plate 7, Figures 1a-c; text-figure 1, no. K
- Areosphaeridium arcuatum Eaton 1971, pl. 3, fig. 4, not figs. 1-3, 5-9 [not pl. 3, fig. 1 which is the holotype of Enneadocysta (as Areosphaeridium) arcuata].
Description:
Shape: Cysts skolochorate with subspherical to ellipsoidal central body and with slightly offset parasulcal notch.
Wall relationships: Autophragm only.
Wall features: Autophragm smooth or coarsely pitted, with 18 intratabular processes, nine on epicyst and nine on hypocyst; paracingular processes absent. Processes short, relative to body diameter, similar in length but variable in width; generally markedly expanded distally with recurved, branched, buccinate or licrate terminations. Arcuations of licrate structures tend to be short and shallow, and the branched or buccinate ends may be spinulate or irregularly perforate. Open ends of licrite structures on the two opposed antapical processes face each other medially.
Excystrnent type: Archeopyle apical; although isolated opercula have not been observed. Based on body shapes, some opercula may be slightly longer transversely than dorso-ventrally.
Paratabulation: Expressed on epicyst by principal and accessory archeopyle sutures and positions of intratabular processes; on hypocyst by process locations only. Process formula: ?4", 6"", 0c, 6""", 2"""", 1ps; anterior margin of paraplate 6"" peaked asymmetrically, left side shorter than right. This paraplate lacks a process and is slightly narrower than paraplate 1"". Configuration of hypocystal processes partiform.
Paracingulum: Delineated by absence of processes.
Parasulcus: Limits of parasulcus expressed anteriorly by parasulcal notch and posteriorly by posterior parasulcal process.
Size: Intermediate; body diameter 50 Ám to 62 Ám, overall diameter 67 Ám to 85 Ám, process length 10 Ám to 15 Ám, process width at midlength 2.5 Ám to 8.0 Ám; wider processes usually restricted to dorsal and lateral surfaces.
Comments
Enneadocysta robusta does not have processes on the sixth precingular paraplate (pl. 7, fig. 1c) or on any of the cingular paraplates (pl. 7, figs. 1a-c).
Holotype:
Specimen illustrated in Plate 7, Figures 1a-c. Location: EPR slide 2753V-R, coordinates R04.8+19.8, Exxon Production Co., Research Center, Houston, Texas, U.S.A.
Type locality and stratum:
Locality: Belgium Basin, Assenede Well at coordinates 107.614/215.180, Belgium.
Stratum: Core sample 21 at 71.40 meters (lower Middle Eocene, Lutetian).
Stratigraphic and geographic data:
Early Mid Eocene (Lutetian). The species is known from strata within the 44 Ma depositional sequence only.
Enneadocysta robusta is recorded solely from Northern Hemisphere localities in Belgium and England. These are: Belgian Basin, Assenede Well (lower Middle Eocene) and the Hampshire Basin, southern England, Isle of Wight, Whitecliff Bay section (lower Middle Eocene).
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