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Areosphaeridium suggestium
Areosphaeridium suggestium, McMinn, 1988
Holotype: McMinn, 1988, figs.3A,C
Occurrence: rare to common in the Areosphaeridium suggestium and Areoligera coronata Zones (Santonian to middle Campanian) of the Carnarvon, Canning, Browse and Bonaparte Basins.
Age: Santonian-Middle Campanian
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Original description: [McMinn, 1988]:
Description:
Chorate, subspherical to ellipsoidal cysts. The cyst wall consists of a thin autophragm (approximately 0.5 μm thick), with a smooth to faintly granular surface. The autophragm supports between one and four intratabular processes per paraplate; the number of processes per paraplate is usually constant on individual specimens. The processes are solid and narrow with a maximum length between 17 μm and 41 μm (average 27 μm). They are slightly expanded at the base and the distal extremities are expanded into a flat or occasionally recurved fenestrate platform. These platforms consist of a central rib bordered by one or two rows of picot-like perforations. Specimens with intratabular process clusters sometimes have the fenestrate platforms joined to adjacent platforms by fine trabeculae. Some of the specimens with intratabular process clusters also have low proximal ridges connecting the processes in incomplete peritabular rings.
The archeopyle is apical, type [tA], the operculum is usually free. Accessory archeopyle sutures are commonly developed adjacent to and between the precingular paraplates. The archeopyle margin and process distribution suggest a paratabulation formula of 4', 6", 6c, 6'", lp, 1'"', 3-6s.
The sulcal processes are distinguished by their smaller size; the cingular processes are similar in size to the non-sulcal processes.
Dimensions:
Size - Autocyst (excluding processes); length (including operculum) 75(54)44 μm, width 72(56)50 μm. Twenty specimens were measured.
Affinities/Comparison:
Areosphaeridium suggestium is distinguished from both Areosphaeridium fenestratum Bujak 1976 and Areosphaeridium diktyoplokus (Klumpp) Eaton 1971 by its larger size and smaller fenestrate platforms. It differs from Rigaudella apenninica (Corradini) Below 1982b by having only a single wall layer and by having cingular and sulcal processes. It differs from Oligosphaeridium puleherrimum (Deflandre & Cookson) Davey & Williams 1966 by having cingular processes. Comments. This species is assigned to Areosphaeridium because it has an apical archeopyle and solid, intratabular processes with prominent distal platforms.
Holotype: McMinn, 1988, figs.3A,C
Occurrence: rare to common in the Areosphaeridium suggestium and Areoligera coronata Zones (Santonian to middle Campanian) of the Carnarvon, Canning, Browse and Bonaparte Basins.
Age: Santonian-Middle Campanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [McMinn, 1988]:
Description:
Chorate, subspherical to ellipsoidal cysts. The cyst wall consists of a thin autophragm (approximately 0.5 μm thick), with a smooth to faintly granular surface. The autophragm supports between one and four intratabular processes per paraplate; the number of processes per paraplate is usually constant on individual specimens. The processes are solid and narrow with a maximum length between 17 μm and 41 μm (average 27 μm). They are slightly expanded at the base and the distal extremities are expanded into a flat or occasionally recurved fenestrate platform. These platforms consist of a central rib bordered by one or two rows of picot-like perforations. Specimens with intratabular process clusters sometimes have the fenestrate platforms joined to adjacent platforms by fine trabeculae. Some of the specimens with intratabular process clusters also have low proximal ridges connecting the processes in incomplete peritabular rings.
The archeopyle is apical, type [tA], the operculum is usually free. Accessory archeopyle sutures are commonly developed adjacent to and between the precingular paraplates. The archeopyle margin and process distribution suggest a paratabulation formula of 4', 6", 6c, 6'", lp, 1'"', 3-6s.
The sulcal processes are distinguished by their smaller size; the cingular processes are similar in size to the non-sulcal processes.
Dimensions:
Size - Autocyst (excluding processes); length (including operculum) 75(54)44 μm, width 72(56)50 μm. Twenty specimens were measured.
Affinities/Comparison:
Areosphaeridium suggestium is distinguished from both Areosphaeridium fenestratum Bujak 1976 and Areosphaeridium diktyoplokus (Klumpp) Eaton 1971 by its larger size and smaller fenestrate platforms. It differs from Rigaudella apenninica (Corradini) Below 1982b by having only a single wall layer and by having cingular and sulcal processes. It differs from Oligosphaeridium puleherrimum (Deflandre & Cookson) Davey & Williams 1966 by having cingular processes. Comments. This species is assigned to Areosphaeridium because it has an apical archeopyle and solid, intratabular processes with prominent distal platforms.