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Senoniasphaera edenensis
Senoniasphaera edenensis Marshall, 1990
Holotype: Marshall, 1990, figs.9A-B, 15R-T
Locus typicus: Gippsland Basin, Southeastern Australia
Stratum typicum: Campanian
Original description: Marshall, 1990, p.18
Cysts with subpentagonal ventrodorsal outlines, marked by 1 apical, 2 antapical, and often, 2 lateral horns forming broad, rounded, subconical structures. Cysts circumcavate, wall layers appressed on middorsal and midventral surfaces. Scattered solid pillars extend normally between wall layers around periphery of cyst; pillars tapering towards midlength where they are usually up to 1 µm thick. Additional finer pillars occur in greater frequencies around the edges of the mid-dorsal and midventral surfaces where wall layers are in close proximity. Endophragm smooth, c. 1 µm thick; ventrodorsal endocyst outline subcircular. Periphragm c. 0.5 µm thick, frequently folded and distorted, bearing numerous perforations and circular, shallow pits. Diameter of pits 1.0-2.5 µm. Perforations close spaced and extremely fine, less than 0.5 µm in diameter where layers are appressed, becoming larger and more sparsely distributed where separated. Periphragm marked by parasutural folds with rounded to angular crests. Wall layers usually separated beneath folds and periphragm frequently split apart along the crests. Paratabulation incomplete, with only parts of paraplates usually evident; pattern clearest on dorsal surface. Specimens with well developed paratabulation show paraplates 2-4", 3-5""", and 1"""" (Fig. 9AE). Paracingulum indicated on dorsal and edges of ventral surfaces by a shallow groove bordered by two ridges 5 µm apart. Archeopyle apical, Type (tA), accessory sutures usually evident on both wall layers of operculum and main body.
Dimensions. Cyst without operculum: pericyst length 55(70)78 µm, width 65(81)99 µm; endocyst length 49(56)65 µm, width 56(64)74 µm (15 specimens).
Type material. Holotype (Fig. 15R-T) pericyst length 69 µm, width 84 µm; endocyst length 49 µm, width 63 µm.
Affinities:
Marshall, 1990, p.18: The closely spaced, fine perforations on the periphragm where the wall layers are appressed produce a fenestrate appearance. The combination of the splits along the crests of the parasutural folds, and the fine perforations and unusual pits on the dorsal surface of the periphragm, gives the individual paraplate surfaces within this area a distinctive appearance.
This species differs from Canningia bassensis in having a more complete outer wall layer which is in contact with an endocyst over much of the ventral and dorsal surfaces. The cavity between the wall layers around the periphery of S. edenensis only contains scattered pillars and these are usually thicker than those on C. bassensis.
Holotype: Marshall, 1990, figs.9A-B, 15R-T
Locus typicus: Gippsland Basin, Southeastern Australia
Stratum typicum: Campanian
Original description: Marshall, 1990, p.18
Cysts with subpentagonal ventrodorsal outlines, marked by 1 apical, 2 antapical, and often, 2 lateral horns forming broad, rounded, subconical structures. Cysts circumcavate, wall layers appressed on middorsal and midventral surfaces. Scattered solid pillars extend normally between wall layers around periphery of cyst; pillars tapering towards midlength where they are usually up to 1 µm thick. Additional finer pillars occur in greater frequencies around the edges of the mid-dorsal and midventral surfaces where wall layers are in close proximity. Endophragm smooth, c. 1 µm thick; ventrodorsal endocyst outline subcircular. Periphragm c. 0.5 µm thick, frequently folded and distorted, bearing numerous perforations and circular, shallow pits. Diameter of pits 1.0-2.5 µm. Perforations close spaced and extremely fine, less than 0.5 µm in diameter where layers are appressed, becoming larger and more sparsely distributed where separated. Periphragm marked by parasutural folds with rounded to angular crests. Wall layers usually separated beneath folds and periphragm frequently split apart along the crests. Paratabulation incomplete, with only parts of paraplates usually evident; pattern clearest on dorsal surface. Specimens with well developed paratabulation show paraplates 2-4", 3-5""", and 1"""" (Fig. 9AE). Paracingulum indicated on dorsal and edges of ventral surfaces by a shallow groove bordered by two ridges 5 µm apart. Archeopyle apical, Type (tA), accessory sutures usually evident on both wall layers of operculum and main body.
Dimensions. Cyst without operculum: pericyst length 55(70)78 µm, width 65(81)99 µm; endocyst length 49(56)65 µm, width 56(64)74 µm (15 specimens).
Type material. Holotype (Fig. 15R-T) pericyst length 69 µm, width 84 µm; endocyst length 49 µm, width 63 µm.
Affinities:
Marshall, 1990, p.18: The closely spaced, fine perforations on the periphragm where the wall layers are appressed produce a fenestrate appearance. The combination of the splits along the crests of the parasutural folds, and the fine perforations and unusual pits on the dorsal surface of the periphragm, gives the individual paraplate surfaces within this area a distinctive appearance.
This species differs from Canningia bassensis in having a more complete outer wall layer which is in contact with an endocyst over much of the ventral and dorsal surfaces. The cavity between the wall layers around the periphery of S. edenensis only contains scattered pillars and these are usually thicker than those on C. bassensis.