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Dichadogonyaulax culmula ssp. curtospina
From Fensome et al., 2019:
Dichadogonyaulax culmula ssp. curtospina (Quattrocchio and Sarjeant, 1992, p.90 (al. 2–242), pl.6, figs.3,6) Lentin and Williams,
1993, p.178. Holotype: Quattrocchio and Sarjeant, 1992, pl.6, fig.6. Originally Dichadogonyaulax culmula var. curtospina, subsequently (and now) Dichadogonyaulax culmula subsp. curtospina. Age: middle–late Tithonian.
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Original description: [Quattrocchio and Sarjeant, 1992]:
Dichadogonyaulax culmula (Norris, 1965) varietas curtospina nov.
(Plate 6, Figs. 3, 6).
Derivatio nominis. L. curtus, short: spinosus, thorny.
Diagnosis. A variety of Dichadogonyaulax culmula having sutural spines only half the length of those of typical forms (less than one-tenth of the central body width) and proximally entire.
llustrated specimens. Holotype: 2967/5: 8,8/140 (Plate 6, Fig. 6). Figured specimen: 2967/1: 16,2/102,8 (Plate 7, Fig. 3)
Lodgement. Palynological Laboratory, Universidad Nacional del Sur, Bahia Blanca.
Description. Cysts proximochorate; body subspherical, ovoidal or polygonal. Paratabulation gonyaulacacean, indicated by smooth parasutural ridges giving rise to regularly spaced, stout processes with briefly bifurcate distal ends. Branches oriented transversely to the rows of processes; in some instances, one branch is longer than the other. Sutural development on either side of paracingulum symmetrical. Paratabulation formula: 4', 1a, 6", 6c, 6'", 1p, 1"", 5s. Phragma surface between parasutural features smooth, granulate to punctate, with a few isolated bifurcate projections (0.5-1.0 μm in height).
Precingular paraplates approximately equidimensional, except 1" which is reduced to accommodate the posterior intercalary paraplate (1p).
Archaeopyle epitractal, formed by schism along a line anterior to the paracingulum. Schism is initiated dorsally, the operculum frequently remaining attached ventrally at the parasulcus.
Dimensions. Holotype: overall length 37 μm, breadth 34 μm. Range: overal length 36-40 μm, breadth 34-35 μm, process length 3 μm (8 specimens measured).
Remarks. The processes in typical D. culmula are markedly longer (7 to 10 μm) than in the specimens here studied. Spine bases are entire, not showing the elongate punctations seen in typical forms. Neither of these features is considered sufficiently important to justify differentiation of these forms at a taxonomic level higher than varietal; moreover, it is likely that, given a more extensive material, intermediate forms might be encountered.
Dichadogonyaulax culmula ssp. curtospina (Quattrocchio and Sarjeant, 1992, p.90 (al. 2–242), pl.6, figs.3,6) Lentin and Williams,
1993, p.178. Holotype: Quattrocchio and Sarjeant, 1992, pl.6, fig.6. Originally Dichadogonyaulax culmula var. curtospina, subsequently (and now) Dichadogonyaulax culmula subsp. curtospina. Age: middle–late Tithonian.
---------------------------------------------------------------------------------------------------
Original description: [Quattrocchio and Sarjeant, 1992]:
Dichadogonyaulax culmula (Norris, 1965) varietas curtospina nov.
(Plate 6, Figs. 3, 6).
Derivatio nominis. L. curtus, short: spinosus, thorny.
Diagnosis. A variety of Dichadogonyaulax culmula having sutural spines only half the length of those of typical forms (less than one-tenth of the central body width) and proximally entire.
llustrated specimens. Holotype: 2967/5: 8,8/140 (Plate 6, Fig. 6). Figured specimen: 2967/1: 16,2/102,8 (Plate 7, Fig. 3)
Lodgement. Palynological Laboratory, Universidad Nacional del Sur, Bahia Blanca.
Description. Cysts proximochorate; body subspherical, ovoidal or polygonal. Paratabulation gonyaulacacean, indicated by smooth parasutural ridges giving rise to regularly spaced, stout processes with briefly bifurcate distal ends. Branches oriented transversely to the rows of processes; in some instances, one branch is longer than the other. Sutural development on either side of paracingulum symmetrical. Paratabulation formula: 4', 1a, 6", 6c, 6'", 1p, 1"", 5s. Phragma surface between parasutural features smooth, granulate to punctate, with a few isolated bifurcate projections (0.5-1.0 μm in height).
Precingular paraplates approximately equidimensional, except 1" which is reduced to accommodate the posterior intercalary paraplate (1p).
Archaeopyle epitractal, formed by schism along a line anterior to the paracingulum. Schism is initiated dorsally, the operculum frequently remaining attached ventrally at the parasulcus.
Dimensions. Holotype: overall length 37 μm, breadth 34 μm. Range: overal length 36-40 μm, breadth 34-35 μm, process length 3 μm (8 specimens measured).
Remarks. The processes in typical D. culmula are markedly longer (7 to 10 μm) than in the specimens here studied. Spine bases are entire, not showing the elongate punctations seen in typical forms. Neither of these features is considered sufficiently important to justify differentiation of these forms at a taxonomic level higher than varietal; moreover, it is likely that, given a more extensive material, intermediate forms might be encountered.