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Araneosphaera araneosa
Araneosphaera araneosa, Eaton, 1976
Holotype: Eaton, 1976, pl.2, fig.6; Bujak et al., 1980, pl.6, figs.4-5
Locus typicus: Bracklesham Beds, Whitecliff Bay, Isle of Wight, England.
Stratum typicum: Middle-Late Eocene
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Original description: [Eaton, 1976, p. 242]:
Description:
Cyst body spherical or subspherical with a smooth or finely fibroreticulate surface.
Processes intratabular, fibrous, simple or branched, proximally and distally expanded, may exhibit stem fenestration. Apical and precingular processes short, usually distally free, one per reflected plate area. Cingular zone typically devoid of processes, but an occasional one may be present. Processes on postcingular and antapical zones longer than those on the epitract, distally united by a usually irregularly fenestrate fibrous membrane. On these zones there is basically one process per reflected plate area. Additional processes are present, intermediate in position between the postcingular and antapical processes.
Reflected tabulation 4', 6", 5-6''', 0-1p, 1'''';
archaeopyle precingular, formed by displacement of plate 3".
Dimensions:
Holotype: overall 103 x 82 µm; diameter of cyst body 50 µm; length of processes up to 38 µm.
Observed range: overall 94 x 83 µm to 110 X 110 µm; diameter of cyst body 44-58 µm; length of processes up to 43 µm. (n = 20).
Affinities:
The majority of the apical and precingular processes are typically distally free. Occasionally some of these processes may be distally united, while process 6" is usually distally united across the cingular zone with the postcingular processes. Occasionally a process can be interpreted as being cingular in position, but the cingular zone is typically devoid of processes. The precingular and antapical processes are always distally united by fibrous membrane which frequently shows the development of irregular fenestrations. These processes are often branched, and may show stem fenestration. Up to four additional processes have been observed between, and distally united with, the five or six primary postcingular processes and the antapical process. One of these is interpreted as reflecting the posterior intercalary plate (1p), while the others possibly represent additional process development on the postcingular zone. The combination of process form and distribution archaeopyle position, and the presence of membrane distally uniting the hypotractai processes, distinguishes Araneosphaera araneosa from all described species of dinoflagellate cyst.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Araneosphaera araneosa Eaton, 1976. According to Eaton (1976, p.242), this species has a cyst body with a smooth or finely fibro-reticulate surface. Processes intratabular, fibrous, simple or branched, proximally and distally expanded, may have stem fenestrations. Apical and precingular processes short, usually distally free. Cingular zone usually devoid of processes, but an occasional one may be present. Postcingular and antapical processes longer, distally united by a usually irregularly fenestrate fibrous membrane. Usually one process per plate but may be additional processes intermediate in position between the postcingular and antapical processes. Process 6" can sometimes be distally united with the postcingular processes. Tabulation 4', 6", 5-6"’, 0-1p, 1"”.
Holotype: Eaton, 1976, pl.2, fig.6; Bujak et al., 1980, pl.6, figs.4-5
Locus typicus: Bracklesham Beds, Whitecliff Bay, Isle of Wight, England.
Stratum typicum: Middle-Late Eocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Eaton, 1976, p. 242]:
Description:
Cyst body spherical or subspherical with a smooth or finely fibroreticulate surface.
Processes intratabular, fibrous, simple or branched, proximally and distally expanded, may exhibit stem fenestration. Apical and precingular processes short, usually distally free, one per reflected plate area. Cingular zone typically devoid of processes, but an occasional one may be present. Processes on postcingular and antapical zones longer than those on the epitract, distally united by a usually irregularly fenestrate fibrous membrane. On these zones there is basically one process per reflected plate area. Additional processes are present, intermediate in position between the postcingular and antapical processes.
Reflected tabulation 4', 6", 5-6''', 0-1p, 1'''';
archaeopyle precingular, formed by displacement of plate 3".
Dimensions:
Holotype: overall 103 x 82 µm; diameter of cyst body 50 µm; length of processes up to 38 µm.
Observed range: overall 94 x 83 µm to 110 X 110 µm; diameter of cyst body 44-58 µm; length of processes up to 43 µm. (n = 20).
Affinities:
The majority of the apical and precingular processes are typically distally free. Occasionally some of these processes may be distally united, while process 6" is usually distally united across the cingular zone with the postcingular processes. Occasionally a process can be interpreted as being cingular in position, but the cingular zone is typically devoid of processes. The precingular and antapical processes are always distally united by fibrous membrane which frequently shows the development of irregular fenestrations. These processes are often branched, and may show stem fenestration. Up to four additional processes have been observed between, and distally united with, the five or six primary postcingular processes and the antapical process. One of these is interpreted as reflecting the posterior intercalary plate (1p), while the others possibly represent additional process development on the postcingular zone. The combination of process form and distribution archaeopyle position, and the presence of membrane distally uniting the hypotractai processes, distinguishes Araneosphaera araneosa from all described species of dinoflagellate cyst.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Araneosphaera araneosa Eaton, 1976. According to Eaton (1976, p.242), this species has a cyst body with a smooth or finely fibro-reticulate surface. Processes intratabular, fibrous, simple or branched, proximally and distally expanded, may have stem fenestrations. Apical and precingular processes short, usually distally free. Cingular zone usually devoid of processes, but an occasional one may be present. Postcingular and antapical processes longer, distally united by a usually irregularly fenestrate fibrous membrane. Usually one process per plate but may be additional processes intermediate in position between the postcingular and antapical processes. Process 6" can sometimes be distally united with the postcingular processes. Tabulation 4', 6", 5-6"’, 0-1p, 1"”.