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Isabelidinium rhombovale
From Fensome et al., 2019:
Isabelidinium? rhombovale (Cookson and Eisenack, 1970a, p.143, pl.12, figs.10–11) Lentin and Williams, 1977a, p.168. Holotype: Cookson and Eisenack, 1970a, pl.12, fig.11. Originally Deflandrea, subsequently Isabelia (combination illegitimate), thirdly Isabelidinium, fourthly (and now) Isabelidinium?. Questionable assignment: Stover and Evitt (1978, p.109). Age: late Albian–Senonian.
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Locus typicus: Madura No. 1 Bore Eucla Basin, W Australia
Stratum typicum: Late Albian-Senonian
Original description: Cookson and Eisenack, 1970, p.143: Deflandrea rhombovalis
Shell small, somewhat flat, rounded-rhomboidal to nearly oval in outline, with a short, blunt to truncate apical horn and a small, pointed to rounded antapical horn situated towards one side of the hypotheca. Girdle median, slightly indicated or missing. In the holotype the ventral furrow is in evidence and the wavy thickening which we associate with the flagellum pore and have herein recorded for several other types is clearly indicated.
The capsule is approximately circular in outline and does not fill the shell laterally; its wall is only slightly thicker than that of the shell. The shell opens by means of a small, approximately five-sided archeopyle, as is evident in the holotype, but to one side of the epitheca due to faulty preservation.
Dimensions: Based on 20 examples. Holotype: length c. 54 µm, breadth 44 µm. Range: length c. 46-56 µm, breadth 36-44 µm.
Affinities:
Cookson and Eisenack, 1970, p.143: Deflandrea rhombovalis
The differences between this species and other small and smooth species of Deflandrea are the blunt, truncate and slightly inverted apical horn and the pointed antapical horn.
Isabelidinium? rhombovale (Cookson and Eisenack, 1970a, p.143, pl.12, figs.10–11) Lentin and Williams, 1977a, p.168. Holotype: Cookson and Eisenack, 1970a, pl.12, fig.11. Originally Deflandrea, subsequently Isabelia (combination illegitimate), thirdly Isabelidinium, fourthly (and now) Isabelidinium?. Questionable assignment: Stover and Evitt (1978, p.109). Age: late Albian–Senonian.
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Locus typicus: Madura No. 1 Bore Eucla Basin, W Australia
Stratum typicum: Late Albian-Senonian
Original description: Cookson and Eisenack, 1970, p.143: Deflandrea rhombovalis
Shell small, somewhat flat, rounded-rhomboidal to nearly oval in outline, with a short, blunt to truncate apical horn and a small, pointed to rounded antapical horn situated towards one side of the hypotheca. Girdle median, slightly indicated or missing. In the holotype the ventral furrow is in evidence and the wavy thickening which we associate with the flagellum pore and have herein recorded for several other types is clearly indicated.
The capsule is approximately circular in outline and does not fill the shell laterally; its wall is only slightly thicker than that of the shell. The shell opens by means of a small, approximately five-sided archeopyle, as is evident in the holotype, but to one side of the epitheca due to faulty preservation.
Dimensions: Based on 20 examples. Holotype: length c. 54 µm, breadth 44 µm. Range: length c. 46-56 µm, breadth 36-44 µm.
Affinities:
Cookson and Eisenack, 1970, p.143: Deflandrea rhombovalis
The differences between this species and other small and smooth species of Deflandrea are the blunt, truncate and slightly inverted apical horn and the pointed antapical horn.