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Diphasiosphaera stolidota
Diphasiosphaera stolidota Duxbury, 1980
Now Hystrichostrogylon. Originally Diphasiosphaera, subsequently (and now) Hystrichostrogylon.
Holotype: Duxbury, 1980, pl.1, fig. 5, text-fig.6
Locus typicus: Speeton Clay, Speeton, England
Stratum typicum: Barremian
Original diagnosis: Duxbury, 1980, p.116
A cavate dinoflagellate cyst which is distinctly bi-layered and consists of a smooth, spheroidal endoblast and a smooth to finely perforate, spheroidal periblast. The periplast bears a distinct apical projection and has a large sulcal hole. Both body layers are characteristically extensively folded. Apparently typically gonyaulacacean paratabulation is outlined on the periblast by parasutural processes of varying height. The archeopyle is single-paraplate precingular (3"). Around the archeopyle margin, where the two body layers are appressed, the full development of fairly closely-spaced parasutural processes is seen and in this area, parasutural crests may proximally connect the processes. Away from the archeopyle margin and that part of the paracingulum directly posterior to it, the parasutural processes are reduced to a varying extent. As a rule, the greater the distance between the body layers, the shorter the parasutural processes, so that in the ventral area they may be reduced to nothing.
Observed Dimensions: Holotype 86x 70 µm. Overall 95(76)65x92(69)59 µm.
Affinities:
Duxbury, 1980, p. 116: This is a very distinctive species, particularly in the extent of its cavation and in the mode of attachment of the body layers. The parasutural processes, at their fullest development, are similar to those of some species of Spiniferites Mantell, 1850 emend. Sarjeant, 1970. Reduction of processes in the more cavate regions involves firstly the loss of process "stalks" so that one may see double rows of spines marking out paraplate boundaries with these spines representing the distal bifurcation of parasutural processes. Eventually, when the cavation reaches a sufficient extent, the double rows are reduced to nothing.
Now Hystrichostrogylon. Originally Diphasiosphaera, subsequently (and now) Hystrichostrogylon.
Holotype: Duxbury, 1980, pl.1, fig. 5, text-fig.6
Locus typicus: Speeton Clay, Speeton, England
Stratum typicum: Barremian
Original diagnosis: Duxbury, 1980, p.116
A cavate dinoflagellate cyst which is distinctly bi-layered and consists of a smooth, spheroidal endoblast and a smooth to finely perforate, spheroidal periblast. The periplast bears a distinct apical projection and has a large sulcal hole. Both body layers are characteristically extensively folded. Apparently typically gonyaulacacean paratabulation is outlined on the periblast by parasutural processes of varying height. The archeopyle is single-paraplate precingular (3"). Around the archeopyle margin, where the two body layers are appressed, the full development of fairly closely-spaced parasutural processes is seen and in this area, parasutural crests may proximally connect the processes. Away from the archeopyle margin and that part of the paracingulum directly posterior to it, the parasutural processes are reduced to a varying extent. As a rule, the greater the distance between the body layers, the shorter the parasutural processes, so that in the ventral area they may be reduced to nothing.
Observed Dimensions: Holotype 86x 70 µm. Overall 95(76)65x92(69)59 µm.
Affinities:
Duxbury, 1980, p. 116: This is a very distinctive species, particularly in the extent of its cavation and in the mode of attachment of the body layers. The parasutural processes, at their fullest development, are similar to those of some species of Spiniferites Mantell, 1850 emend. Sarjeant, 1970. Reduction of processes in the more cavate regions involves firstly the loss of process "stalks" so that one may see double rows of spines marking out paraplate boundaries with these spines representing the distal bifurcation of parasutural processes. Eventually, when the cavation reaches a sufficient extent, the double rows are reduced to nothing.