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Diacanthum argentinum
From Fensome et al., 2019:
Diacanthum argentinum Quattrocchio and Sarjeant, 1992, p.86–87(al. 2–238 — 2–239), pl.4, figs.10–13; pl.6, fig.4; textfigs.
8A–B. Holotype: Quattrocchio and Sarjeant, 1992, pl.6, fig.4. Age: middle–late Tithonian.
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Original description: [Quattrocchio and Sarjeant, 1992]:
Diacanthum argentinum sp. nov.
(Plate 4, Figs. 10-13; Plate 6, Fig. 4; Text-Figure 8)
Derivatio nominis. L., argentinum, of Argentina.
Diagnosis. Cysts proximate, acavate; ambitus spherical to broadly ovoidal, with a low-amplitude bulge at the apex. Phragma unilayered apparently so (autophragm). Paratabulation gonyaulacacean, indicated by rows of short spines (0.5 to 1.0 μm height) or by ill-defined,
low (<1.0 μm) echinate crests. L-type ventral organization. Paracingulum delimited by transverse parallel parasutural ridges, strongly helicoid, its ends being displaced relatively by more than one cingulum width. Sulcus approximately meridional, delimited by rows of spines; anterior portion short and more or less straight, with an anterior sulcal paraplate feebly marked, broadening posteriorly, without apparent division into posterior paraplates. Nontabular spines and granules (0.5 to 1.0 μm height) present between parasutural features, except on the cingulum and sulcus where ornamentation is absent. Tentative paratabulation formula: 1 pr, 4', 5", Xc, 6'", 1p, 1"", Xs. Paraplate 1pr constitutes the apical bulge. The as/1' parasuture forms the shortest rectilinear segment in this Succession. Paraplate 1' is elongate and is in distal contact with para-
plates 1pr, 4' and 2'. Paraplates 2' to 4' are of similar size and shape. Paraplate 1" is somewhat reduced antero-posteriorly, 5" and 1" narrow and elongate, 2" and 1'" reduced in comparison with the other, broadly polygonal and quadrangular pre- and postcingular paraplates. Archaeopyle precingular, 2P (3" + 4"); operculum free or attached.
Illustrated specimens. Holotype: 2967/1: 19,6/11,7 (Plate 6, Fig. 4): Text-Fig. 8). Paratype: 2967/5: 13,2/145 X (Plate 4, Fig. 13). Other: 2967/2: 27,3/1 02,6 X (Plate 4, Fig. 10).
Lodgement. Palynological Laboratory, Universidad Nacional del Sur, Bahia Blanca.
Dimensions. Holotype: overall length 53 μm, overall breadth 46 μm. Paratype: overall length 40 μm, overall breadth 45 μm. Range: overall
length 39-53 μm, maximum breadth 39-50 μm (10 specimens measured).
Remarks. Parasutural ridges are not always clearly differentiated, owing to the presence of folds. Surface ornamentation tends also to obscure plate boundaries.
This new species is common in the Upper Middle Tithonian and Upper Tithonian (2967, 2968 and 2969 levels).
Diacanthum argentinum Quattrocchio and Sarjeant, 1992, p.86–87(al. 2–238 — 2–239), pl.4, figs.10–13; pl.6, fig.4; textfigs.
8A–B. Holotype: Quattrocchio and Sarjeant, 1992, pl.6, fig.4. Age: middle–late Tithonian.
---------------------------------------------------------------------------------------------------
Original description: [Quattrocchio and Sarjeant, 1992]:
Diacanthum argentinum sp. nov.
(Plate 4, Figs. 10-13; Plate 6, Fig. 4; Text-Figure 8)
Derivatio nominis. L., argentinum, of Argentina.
Diagnosis. Cysts proximate, acavate; ambitus spherical to broadly ovoidal, with a low-amplitude bulge at the apex. Phragma unilayered apparently so (autophragm). Paratabulation gonyaulacacean, indicated by rows of short spines (0.5 to 1.0 μm height) or by ill-defined,
low (<1.0 μm) echinate crests. L-type ventral organization. Paracingulum delimited by transverse parallel parasutural ridges, strongly helicoid, its ends being displaced relatively by more than one cingulum width. Sulcus approximately meridional, delimited by rows of spines; anterior portion short and more or less straight, with an anterior sulcal paraplate feebly marked, broadening posteriorly, without apparent division into posterior paraplates. Nontabular spines and granules (0.5 to 1.0 μm height) present between parasutural features, except on the cingulum and sulcus where ornamentation is absent. Tentative paratabulation formula: 1 pr, 4', 5", Xc, 6'", 1p, 1"", Xs. Paraplate 1pr constitutes the apical bulge. The as/1' parasuture forms the shortest rectilinear segment in this Succession. Paraplate 1' is elongate and is in distal contact with para-
plates 1pr, 4' and 2'. Paraplates 2' to 4' are of similar size and shape. Paraplate 1" is somewhat reduced antero-posteriorly, 5" and 1" narrow and elongate, 2" and 1'" reduced in comparison with the other, broadly polygonal and quadrangular pre- and postcingular paraplates. Archaeopyle precingular, 2P (3" + 4"); operculum free or attached.
Illustrated specimens. Holotype: 2967/1: 19,6/11,7 (Plate 6, Fig. 4): Text-Fig. 8). Paratype: 2967/5: 13,2/145 X (Plate 4, Fig. 13). Other: 2967/2: 27,3/1 02,6 X (Plate 4, Fig. 10).
Lodgement. Palynological Laboratory, Universidad Nacional del Sur, Bahia Blanca.
Dimensions. Holotype: overall length 53 μm, overall breadth 46 μm. Paratype: overall length 40 μm, overall breadth 45 μm. Range: overall
length 39-53 μm, maximum breadth 39-50 μm (10 specimens measured).
Remarks. Parasutural ridges are not always clearly differentiated, owing to the presence of folds. Surface ornamentation tends also to obscure plate boundaries.
This new species is common in the Upper Middle Tithonian and Upper Tithonian (2967, 2968 and 2969 levels).