Back
Geiselodinium psilatum
From Fensome et al., 2019:
Geiselodinium? psilatum Jain and Millepied, 1973, p.29–30, pl.2, figs.20–21. Holotype: Jain and Millepied, 1973, pl.2, fig.21. Originally Geiselodinium, subsequently (and now) Geiselodinium?. Questionable assignment: Stover and Evitt (1978, p.231) as a problematic species. Age: Campanian–Maastrichtian.
---------------------------------------------------------------------------------------------------
Original description (Jain and Millepied, 1973):
Geiselodinium psilatum sp. nov.
PI. 2. Figs. 20-21
Holotype- PI. 2, Fig. 21; Slide No. 7759b-5.
Locality- Bore Hole No. CM-1, Senegal, N.W. Africa.
Horizon- Maestrichtian-Campanian.
Diagnosis- Shell elongate to oval in outline, delicate. Capsule large, completely filling periphragm cavity. Periphragm extending both in epi- and hypotract forming one apical and two antapical horns. Transverse furrow or girdle circular. Shell walls smooth. No archaeopyle seen.
Dimensions
Holotype- Shell-length 70 μ, breadth 42 μ; Capsule-length 50 μ, breadth 42 μ, Girdle 4 μ broad; Apical horn-length 8 μ, breadth 8 μ; Antapical horn-length 16 μ, breadth 6 μ.
Observed range- Shell-length 60-100 μ, breadth 40-60 μ; Capsule length 50-60 μ, breadth 40-50 μ; Apical horn-length 8-35 μ, breadth 8-20; Antapical horn-length 6-30 μ, breadth 4-11 μ.
Comparison and Discussion
Forms presently described under Geiselodinium show close re~emblance with general shell shape of Deflandrea but the non-cavate shell without archaeopyle prevents its treatment under Deflandrea. Norris and Sarjeant (1964, p. 30) have suggested that Geiselodinium can be treated as sub-genus of Deflandrea till its generic entity is not classified. But we maintain cavate cyst feature as most important for separating
Deflandrea from other genera and therefore, propose to maintain Geiselodinium at generic level. Astrocysta Davey (1970) seems to be closely related to Geiselodinium.
Geiselodinium? psilatum Jain and Millepied, 1973, p.29–30, pl.2, figs.20–21. Holotype: Jain and Millepied, 1973, pl.2, fig.21. Originally Geiselodinium, subsequently (and now) Geiselodinium?. Questionable assignment: Stover and Evitt (1978, p.231) as a problematic species. Age: Campanian–Maastrichtian.
---------------------------------------------------------------------------------------------------
Original description (Jain and Millepied, 1973):
Geiselodinium psilatum sp. nov.
PI. 2. Figs. 20-21
Holotype- PI. 2, Fig. 21; Slide No. 7759b-5.
Locality- Bore Hole No. CM-1, Senegal, N.W. Africa.
Horizon- Maestrichtian-Campanian.
Diagnosis- Shell elongate to oval in outline, delicate. Capsule large, completely filling periphragm cavity. Periphragm extending both in epi- and hypotract forming one apical and two antapical horns. Transverse furrow or girdle circular. Shell walls smooth. No archaeopyle seen.
Dimensions
Holotype- Shell-length 70 μ, breadth 42 μ; Capsule-length 50 μ, breadth 42 μ, Girdle 4 μ broad; Apical horn-length 8 μ, breadth 8 μ; Antapical horn-length 16 μ, breadth 6 μ.
Observed range- Shell-length 60-100 μ, breadth 40-60 μ; Capsule length 50-60 μ, breadth 40-50 μ; Apical horn-length 8-35 μ, breadth 8-20; Antapical horn-length 6-30 μ, breadth 4-11 μ.
Comparison and Discussion
Forms presently described under Geiselodinium show close re~emblance with general shell shape of Deflandrea but the non-cavate shell without archaeopyle prevents its treatment under Deflandrea. Norris and Sarjeant (1964, p. 30) have suggested that Geiselodinium can be treated as sub-genus of Deflandrea till its generic entity is not classified. But we maintain cavate cyst feature as most important for separating
Deflandrea from other genera and therefore, propose to maintain Geiselodinium at generic level. Astrocysta Davey (1970) seems to be closely related to Geiselodinium.