Back
Hemicystodinium congregatum
Hemicystodinium congregatum Stover, 1977
Now Polysphaeridium. Originally Hemicystodinium, subsequently (and now) Polysphaeridium.
Holotype: Stover, 1977, pl.3, figs.39-42
Locus typicus: Corehole 5/5B, Blake Plateau, Western N Atlantic
Stratum typicum: Middle Oligocene
Original description: Stover, 1977, p. 79
Cysts are chorate with a spherical to subspherical body bearing numerous processes arranged in poorly delimited groups. Endophragm and periphragm are appressed between processes and the latter is smooth to faintly and indistinctly ornamented. Processes are smooth to minutely granular, hollow, tapered, with the bases being generally wider than the slightly expanded, open tips. Some processes occur singularly but the majority are arranged in rectilinear or poorly delimited intratabular groups, and 2 to 5 closely spaced processes may have a common base.
Combination archeopyle of the type A+3A+6P has a nearly straight margin except for the midventral parasulcal tab. Paratabulation is gonyaulacacean, formula is 4",6"",6c,5-6""",1p,1"""",2+?s; paratabulation indicated on epicyst by opercular pieces and on hypocyst by rectilinear and intratabular process groups, with the boundaries between paraplates of the hypocyst sharply to vaguely delimited. Paracingulum indicated by rectilinear process groups, by transverse row of isolated processes or mostly by a combination thereof, with 2 to 5 processes per paraplate. Parasulcal tab with a single process marks the apical position of the parasulcus. A small cluster of processes to the right of those denoting paraplate 1p identifies paraplate ps and marks the antapical limit of the parasulcus. Paraplates 1"""", 1p, and ps are arranged in a triangular pattern on the posterioventral surfacewith 1"""" at the apex.
Overall size 61 to 73 Ám; body 43 to 55 Ám in diameter; processes 8 to 12 Ám in length.
Affinities: Stover, 1977, p. 79
Hemicystodinium congregatum differs from H. zoharyi (Rossignol) Wall, 1967 by having the majority of the processes arranged in rectilinear and intratabular groups in contrast to the more nearly nontabular distribution of processes on H. zoharyi.
Now Polysphaeridium. Originally Hemicystodinium, subsequently (and now) Polysphaeridium.
Holotype: Stover, 1977, pl.3, figs.39-42
Locus typicus: Corehole 5/5B, Blake Plateau, Western N Atlantic
Stratum typicum: Middle Oligocene
Original description: Stover, 1977, p. 79
Cysts are chorate with a spherical to subspherical body bearing numerous processes arranged in poorly delimited groups. Endophragm and periphragm are appressed between processes and the latter is smooth to faintly and indistinctly ornamented. Processes are smooth to minutely granular, hollow, tapered, with the bases being generally wider than the slightly expanded, open tips. Some processes occur singularly but the majority are arranged in rectilinear or poorly delimited intratabular groups, and 2 to 5 closely spaced processes may have a common base.
Combination archeopyle of the type A+3A+6P has a nearly straight margin except for the midventral parasulcal tab. Paratabulation is gonyaulacacean, formula is 4",6"",6c,5-6""",1p,1"""",2+?s; paratabulation indicated on epicyst by opercular pieces and on hypocyst by rectilinear and intratabular process groups, with the boundaries between paraplates of the hypocyst sharply to vaguely delimited. Paracingulum indicated by rectilinear process groups, by transverse row of isolated processes or mostly by a combination thereof, with 2 to 5 processes per paraplate. Parasulcal tab with a single process marks the apical position of the parasulcus. A small cluster of processes to the right of those denoting paraplate 1p identifies paraplate ps and marks the antapical limit of the parasulcus. Paraplates 1"""", 1p, and ps are arranged in a triangular pattern on the posterioventral surfacewith 1"""" at the apex.
Overall size 61 to 73 Ám; body 43 to 55 Ám in diameter; processes 8 to 12 Ám in length.
Affinities: Stover, 1977, p. 79
Hemicystodinium congregatum differs from H. zoharyi (Rossignol) Wall, 1967 by having the majority of the processes arranged in rectilinear and intratabular groups in contrast to the more nearly nontabular distribution of processes on H. zoharyi.