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Tanyosphaeridium prolixispinosum
Tanyosphaeridium prolixispinosum (Davey and Williams, 1966) Duxbury, 1980
Now Oligosphaeridium. Originally (and now) Oligosphaeridium, subsequently Tanyosphaeridium. Lentin and Williams, 1981 retained this species in Oligosphaeridium Davey and Williams, 1966.
Holotype: Davey and Williams, 1966b, pl.8, fig.3; Fauconnier and Masure, 2004, pl.60, figs.2–4.
Locus typicus: Fetcham Mill, Surrey, England
Stratum typicum: Cenomanian
Original description: Davey and Williams, 1966, p. 76: Oligosphaeridium prolixispinosum
The periphragm of the central body and of the processes is smooth. The processes are thin-walled and have a fairly broad base up to 8 µm, with characteristic basal wrinkles. There are noticeable circles beneath the processes where only endophragm is present. The processes are about 3 µm in width for most of their length tapering to 2 µm distally before giving rise to the filiform spines. The spines are extremely delicate, 5 to 8 in number, and up to 15 µm in length. The number of processes varies from 16 to 18, the variation probably due to the number of sulcal processes present. In all specimens there is an obvious apical archaeopyle. Surrounding the archaeopyle are 6 precingular processes, then a diastema before the postcingular processes are reached. This diastema marks the position of the cingulum. The processes on the hypotract are difficult to assign to any dinoflagellate tabulation. There is no obvious antapical process, in fact 3 antapical processes usually seem to be present. The reflected tabulation appears to be (4"), 6", 6""", 3"""" and 1-3s.
Dimensions: holotype: overall width 64 µm, diameter of central body 40 by 20 µm, length of processes 18-24 µm, number of processes 17. Range: Length of central body, 33-43 µm, width 20-29 µm, length of processes 18-29 µm.
Now Oligosphaeridium. Originally (and now) Oligosphaeridium, subsequently Tanyosphaeridium. Lentin and Williams, 1981 retained this species in Oligosphaeridium Davey and Williams, 1966.
Holotype: Davey and Williams, 1966b, pl.8, fig.3; Fauconnier and Masure, 2004, pl.60, figs.2–4.
Locus typicus: Fetcham Mill, Surrey, England
Stratum typicum: Cenomanian
Original description: Davey and Williams, 1966, p. 76: Oligosphaeridium prolixispinosum
The periphragm of the central body and of the processes is smooth. The processes are thin-walled and have a fairly broad base up to 8 µm, with characteristic basal wrinkles. There are noticeable circles beneath the processes where only endophragm is present. The processes are about 3 µm in width for most of their length tapering to 2 µm distally before giving rise to the filiform spines. The spines are extremely delicate, 5 to 8 in number, and up to 15 µm in length. The number of processes varies from 16 to 18, the variation probably due to the number of sulcal processes present. In all specimens there is an obvious apical archaeopyle. Surrounding the archaeopyle are 6 precingular processes, then a diastema before the postcingular processes are reached. This diastema marks the position of the cingulum. The processes on the hypotract are difficult to assign to any dinoflagellate tabulation. There is no obvious antapical process, in fact 3 antapical processes usually seem to be present. The reflected tabulation appears to be (4"), 6", 6""", 3"""" and 1-3s.
Dimensions: holotype: overall width 64 µm, diameter of central body 40 by 20 µm, length of processes 18-24 µm, number of processes 17. Range: Length of central body, 33-43 µm, width 20-29 µm, length of processes 18-29 µm.