Back
Eatonicysta
From Williams et al., 2017:
[Eatonicysta, Stover and Evitt, 1978, p. 41; Emendation: Stover and Williams, 1995, p. 103-104
Type species: originally as Cannosphaeropsis ursulae, Morgenroth, 1966a (pl.3, fig.11)] ; Eatonicysta ursulae, (Morgenroth, 1966) Stover and Evitt, 1978
Age: Early Eocene (Ypresian) to early Mid Eocene (Lutetian)
Geographic distribution: Confined to the Northern Hemisphere
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stover and Evitt, 1978]:
Synopsis:
Cyst proximate; body subspherical with 16 to 21 (typically 17) solid, normally fibrous intratabular processes; processes support ectophragm, which may be thin, smooth, and continuous, or reduced by perforations to an open reticulum; paratabulation gonyaulacacean, indicated by intratabular processes and archaeopyle; latter apical, Type tA.
Description:
Shape: Autocyst subspherical; ectophragm more or less concentric to autophragm, shape commonly modified by folding.
Wall relationships: Ectophragm thin, widely separated from autophragm, and supported by processes.
Wall features: Generally no parasutural features. Processes intratabular, solid, typically fibrous, and expanded distally; autophragm between processes smooth or finely granular; ectophragm thin, smooth, and continuous, or reduced by perforations to an open reticulum whose openings vary in size and shape.
Paratabulation: Indicated by intratabular processes and archaeopyle; gonyaulacacean, formula 3-4`, 6``, 0c or 3-4c, 5```, 0-1p, 1````.
Archaeopyle: Apical, Type tA; principal archaeopyle suture zigzag; operculum free.
Paracingulum: Indicated by the absence of processes or by a few processes on autophragm; occasionally indicated on the ectophragm by low, parallel, transverse, equatorial ridges.
Parasulcus: Generally not indicated.
Size: Intermediate.
Affinities:
Eatonicysta differs from Adnatosphaeridium in having fewer processes and a more complete ectophragm, which is not reduced to trabeculae only. The new genus differs from Membranilarnacia in having relatively long intratabular processes, rather than a few apparently scattered, short processes. For information about postulated relationships between Eatonicysta (as Membranilarnacia) and Areosphaeridium, consult Eaton (1971) and Bujak (1976).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Stover and Williams, 1995:
Synopsis:
Cysts holocavate: autocyst with 17 to 23 hollow or solid, fibroid intratabular processes, which support a fenestrate and reticulate to an irregular, open mesh, net-like ectophragm; paratabulation gonyaulacoid, process formula 4, 6", 0-6c, 5 `, I p, I "`, 0s; 1 " wider than 6", hypocystal configuration standard sexiform: archeopyle apical. operculum tetratabular, simple and free.
Description:
Shape: Body subspherical or nearly so, ectophragm more or less concentric to the body; the shape of the ectophragm may vary because of folding, compression, or damage.
Wall relationships: Cysts holocavate, autophragm bears intratabular processes which support the thinner ectophragm.
Wall features: Autophragm smooth or faintly and uniformly ornamented between processes; processes hollow or solid. in part to almost completely fibroid with expanded tips that merge imperceptibly with the ectophragm; ectophragm smooth, continuous, in part fenestrate and in part reticulate with openings that differ in shape and size, or very irregular with clypeate, perforated areas and relatively large open areas outlined by trabeculae.
Excystment mode: Archeopyle apical; operculum tetratabular, simple, about equidimensional transversely and dorso-ventrally and free.
Paratabulalion: Gonyaulacoid, indicated by positions of intratabular processes and archeopyle sutures: process formula: 3-4`, 6", 0-6c, 5"`, lp, 1"", 0s; first precingular paraplate wider than the sixth; hypocystal process arrangement standard sexiform.
Paracingulum: Indicated by absence of, or presence of up to six, processes; paracingulum may be occasionally expressed additionally on ectophragm by low, parallel, transverse equatorial ridges.
Parasulcus: Anterior end indicated by parasulcal notch, otherwise undifferentiated.
Size: Intermediate to large, specimens are 90 µm to 135 µm in diameter
Remark/Comment:
The emended description supplements that given by Stover and Evitt (1978) by denoting the distribution of the processes on the hypocyst (text-fig. 1, no. B2) and by modifying of the paratabulation formula (text-fig. I, nos. B I -B2, C). It also takes into account the observation of Heilmann-Clausen (1993), who noted that the earliest specimens of Eatonicysta ursulae have hollow processes. This includes the taxon Eatonicysta ursulae subsp.furensis Heilmann-Clausen and Costa 1990.
Affinities/Comparison:
Eatonicysta has processes that may be hollow or solid and which distally are united by a thin ectophragm; in Areosphaeridium, the processes are always solid and are distally free. Eatonicysta differs from Adnatosphaeridium Williams and Downie 1966 by having fewer processes, all of which are intratabular (text-fig.-l, nos. B I -B2, C), and which allow determination of the paratabulation. In contrast, Adnatosphaeridium has more numerous processes arranged mostly in complexes and its ectophragm consists mainly of trabeculae, which may or may not form a network. Thus the paratabulation is commonly difficult to discern and the ectophragm tends to be less extensive than that of Eatonicysta. Membranilarnacia Eisenack 1963a emended Williams and Downie 1966 has a continuous, non-reticulate ectophragm and fewer processes whose relationship to paratabulation has not been demonstrated.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Eatonicysta Stover and Evitt, 1978. Synopsis from Stover and Evitt (1978, p.41), Cysts proximate; body subspherical with 16 to 21 (typically 17) solid, normally fibrous intratabular processes; processes support ectophragm, which may be thin, smooth and continuous, or reduced by perforations to an open reticulum; paratabulation gonyaulacacean, indicated by intratabular processes and archeopyle; latter apical, type tA.
[Eatonicysta, Stover and Evitt, 1978, p. 41; Emendation: Stover and Williams, 1995, p. 103-104
Type species: originally as Cannosphaeropsis ursulae, Morgenroth, 1966a (pl.3, fig.11)] ; Eatonicysta ursulae, (Morgenroth, 1966) Stover and Evitt, 1978
Age: Early Eocene (Ypresian) to early Mid Eocene (Lutetian)
Geographic distribution: Confined to the Northern Hemisphere
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stover and Evitt, 1978]:
Synopsis:
Cyst proximate; body subspherical with 16 to 21 (typically 17) solid, normally fibrous intratabular processes; processes support ectophragm, which may be thin, smooth, and continuous, or reduced by perforations to an open reticulum; paratabulation gonyaulacacean, indicated by intratabular processes and archaeopyle; latter apical, Type tA.
Description:
Shape: Autocyst subspherical; ectophragm more or less concentric to autophragm, shape commonly modified by folding.
Wall relationships: Ectophragm thin, widely separated from autophragm, and supported by processes.
Wall features: Generally no parasutural features. Processes intratabular, solid, typically fibrous, and expanded distally; autophragm between processes smooth or finely granular; ectophragm thin, smooth, and continuous, or reduced by perforations to an open reticulum whose openings vary in size and shape.
Paratabulation: Indicated by intratabular processes and archaeopyle; gonyaulacacean, formula 3-4`, 6``, 0c or 3-4c, 5```, 0-1p, 1````.
Archaeopyle: Apical, Type tA; principal archaeopyle suture zigzag; operculum free.
Paracingulum: Indicated by the absence of processes or by a few processes on autophragm; occasionally indicated on the ectophragm by low, parallel, transverse, equatorial ridges.
Parasulcus: Generally not indicated.
Size: Intermediate.
Affinities:
Eatonicysta differs from Adnatosphaeridium in having fewer processes and a more complete ectophragm, which is not reduced to trabeculae only. The new genus differs from Membranilarnacia in having relatively long intratabular processes, rather than a few apparently scattered, short processes. For information about postulated relationships between Eatonicysta (as Membranilarnacia) and Areosphaeridium, consult Eaton (1971) and Bujak (1976).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Stover and Williams, 1995:
Synopsis:
Cysts holocavate: autocyst with 17 to 23 hollow or solid, fibroid intratabular processes, which support a fenestrate and reticulate to an irregular, open mesh, net-like ectophragm; paratabulation gonyaulacoid, process formula 4, 6", 0-6c, 5 `, I p, I "`, 0s; 1 " wider than 6", hypocystal configuration standard sexiform: archeopyle apical. operculum tetratabular, simple and free.
Description:
Shape: Body subspherical or nearly so, ectophragm more or less concentric to the body; the shape of the ectophragm may vary because of folding, compression, or damage.
Wall relationships: Cysts holocavate, autophragm bears intratabular processes which support the thinner ectophragm.
Wall features: Autophragm smooth or faintly and uniformly ornamented between processes; processes hollow or solid. in part to almost completely fibroid with expanded tips that merge imperceptibly with the ectophragm; ectophragm smooth, continuous, in part fenestrate and in part reticulate with openings that differ in shape and size, or very irregular with clypeate, perforated areas and relatively large open areas outlined by trabeculae.
Excystment mode: Archeopyle apical; operculum tetratabular, simple, about equidimensional transversely and dorso-ventrally and free.
Paratabulalion: Gonyaulacoid, indicated by positions of intratabular processes and archeopyle sutures: process formula: 3-4`, 6", 0-6c, 5"`, lp, 1"", 0s; first precingular paraplate wider than the sixth; hypocystal process arrangement standard sexiform.
Paracingulum: Indicated by absence of, or presence of up to six, processes; paracingulum may be occasionally expressed additionally on ectophragm by low, parallel, transverse equatorial ridges.
Parasulcus: Anterior end indicated by parasulcal notch, otherwise undifferentiated.
Size: Intermediate to large, specimens are 90 µm to 135 µm in diameter
Remark/Comment:
The emended description supplements that given by Stover and Evitt (1978) by denoting the distribution of the processes on the hypocyst (text-fig. 1, no. B2) and by modifying of the paratabulation formula (text-fig. I, nos. B I -B2, C). It also takes into account the observation of Heilmann-Clausen (1993), who noted that the earliest specimens of Eatonicysta ursulae have hollow processes. This includes the taxon Eatonicysta ursulae subsp.furensis Heilmann-Clausen and Costa 1990.
Affinities/Comparison:
Eatonicysta has processes that may be hollow or solid and which distally are united by a thin ectophragm; in Areosphaeridium, the processes are always solid and are distally free. Eatonicysta differs from Adnatosphaeridium Williams and Downie 1966 by having fewer processes, all of which are intratabular (text-fig.-l, nos. B I -B2, C), and which allow determination of the paratabulation. In contrast, Adnatosphaeridium has more numerous processes arranged mostly in complexes and its ectophragm consists mainly of trabeculae, which may or may not form a network. Thus the paratabulation is commonly difficult to discern and the ectophragm tends to be less extensive than that of Eatonicysta. Membranilarnacia Eisenack 1963a emended Williams and Downie 1966 has a continuous, non-reticulate ectophragm and fewer processes whose relationship to paratabulation has not been demonstrated.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Eatonicysta Stover and Evitt, 1978. Synopsis from Stover and Evitt (1978, p.41), Cysts proximate; body subspherical with 16 to 21 (typically 17) solid, normally fibrous intratabular processes; processes support ectophragm, which may be thin, smooth and continuous, or reduced by perforations to an open reticulum; paratabulation gonyaulacacean, indicated by intratabular processes and archeopyle; latter apical, type tA.