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Areoligera sentosa
Areoligera sentosam Eaton, 1976
Holotype: Eaton, 1976, pl.4, figs.1-2; Bujak et al., 1980, pl.9, figs.4-5
Locus typicus: Bracklesham Beds, Alum Bay, Isle of Wight, England.
Stratum typicum: Middle-Late Eocene
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Original description: [Eaton, 1976, p. 246]:
Diagnosis:
Cyst body dorsoventrally flattened with a smooth or finely granular surface. The circular or subcircular outline may be modified by the development of one or two antapical protuberances. Ventral and dorsal surfaces bear sail-like membranes with incised distal margins which form curved troughs and pointed crests surmounted by erect or curved acuminate spines. Ventral membrane restricted to the peripheral zone, aligned parallel to, and situated close to, the margin of the cyst body. Dorsal membranes organized into process complexes which may be arcuate, soleate or annular on the pre- and postcingular zones, linear on the cingular zone, and annular on the antapical zone.
Archaeopyle apical, tetratabular.
Dimensions:
Holotype: cyst body (without operculum) 61 x 77 µm, height of membrane (including spines) up to 25 µm.
Observed range: cyst body (without operculum) 52 x 58 µm to 64 x 80 µm, height of membrane (including spines) up to 32 µm. (n = 26).
Affinities:
The sail-like membranes have a striated fibrous texture apparently due to the presence of numerous minute fenestrations; they may also show the development of large proximal fenestrations. There is some variation in the type of process complex developed on the dorsal surface. Of the three precingular and three postcingular complexes, in both zones, the middle complex is typically arcuate or soleate, while the other two are soleate or annular. Up to four linear complexes have been observed on the cingular zone; the antapical complex is annular. No forms have been recorded with process complexes developed on the ventral surface. The presence of sail-like membranes and the distinctive form of their distal margins distinguish Areoligera sentosa from all described species of Areoligera.
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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.
Areoligera sentosa Eaton, 1976, has sail-like, fenestrate membranes on ventral and dorsal surfaces and these have incised distal margins, which form curved troughs and pointed crests surmounted by erect or curved acuminate spines. Ventral membranes restricted to the peripheral zone aligned parallel to and situated close to the margin. Dorsal membranes forming process complexes which may be arcuate, soleate or annular on the pre- and postcingulars, linear on the cingular and annulate at the antapex.
Size: central body 52 x 58 to 64 x 80 µm. Membrane height up to 32 µm.
Holotype: Eaton, 1976, pl.4, figs.1-2; Bujak et al., 1980, pl.9, figs.4-5
Locus typicus: Bracklesham Beds, Alum Bay, Isle of Wight, England.
Stratum typicum: Middle-Late Eocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Eaton, 1976, p. 246]:
Diagnosis:
Cyst body dorsoventrally flattened with a smooth or finely granular surface. The circular or subcircular outline may be modified by the development of one or two antapical protuberances. Ventral and dorsal surfaces bear sail-like membranes with incised distal margins which form curved troughs and pointed crests surmounted by erect or curved acuminate spines. Ventral membrane restricted to the peripheral zone, aligned parallel to, and situated close to, the margin of the cyst body. Dorsal membranes organized into process complexes which may be arcuate, soleate or annular on the pre- and postcingular zones, linear on the cingular zone, and annular on the antapical zone.
Archaeopyle apical, tetratabular.
Dimensions:
Holotype: cyst body (without operculum) 61 x 77 µm, height of membrane (including spines) up to 25 µm.
Observed range: cyst body (without operculum) 52 x 58 µm to 64 x 80 µm, height of membrane (including spines) up to 32 µm. (n = 26).
Affinities:
The sail-like membranes have a striated fibrous texture apparently due to the presence of numerous minute fenestrations; they may also show the development of large proximal fenestrations. There is some variation in the type of process complex developed on the dorsal surface. Of the three precingular and three postcingular complexes, in both zones, the middle complex is typically arcuate or soleate, while the other two are soleate or annular. Up to four linear complexes have been observed on the cingular zone; the antapical complex is annular. No forms have been recorded with process complexes developed on the ventral surface. The presence of sail-like membranes and the distinctive form of their distal margins distinguish Areoligera sentosa from all described species of Areoligera.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Areoligera sentosa Eaton, 1976, has sail-like, fenestrate membranes on ventral and dorsal surfaces and these have incised distal margins, which form curved troughs and pointed crests surmounted by erect or curved acuminate spines. Ventral membranes restricted to the peripheral zone aligned parallel to and situated close to the margin. Dorsal membranes forming process complexes which may be arcuate, soleate or annular on the pre- and postcingulars, linear on the cingular and annulate at the antapex.
Size: central body 52 x 58 to 64 x 80 µm. Membrane height up to 32 µm.