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Scalenodinium
From Fensome et al., 2019:
Scalenodinium, Fensome et al., 2016b, p.64.
Type: Fensome et al., 2016b, pl.12, fig.15, as Scalenodinium scalenum.
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Original description Fensome et al., 2016b:
Etymology. The name is from the Latin scalenus, meaning unequal, uneven, odd, in reference to the unequal variation in apical and antapical development.
Description. Pericoel elongate, with an apical horn that is acuminate to rounded distally and generally a rounded antapex, although the latter may be extended into a short protuberance. When the endocyst is present, the cyst is bicavate. Cingulum present or faintly expressed. Periarchaeopyle intercalary, generally with formula I2a, and with a free operculum. The hexa 2a plate is stenodeltaform. In some specimens, the apparent loss of the apical area (Plate 12, figs 16–19) or of other intercalary plates besides the 2a (Plate 12, fig. 15) indicates a compound and/or combination archaeopyle.
Remarks. Scalenodinium differs from Isabelidinium in having a stenodeltaform, rather than a lati- to iso-omega-form 2a plate. Palaeocystodinium, which like Scalenodinium has a stenodeltaform 2a plate, differs from the latter genus in always having more or less apical and antapical horns and a periarchaeopyle that is always formed from the loss of a single plate, the 2a plate, rather than several plates as in Scalenodinium.
Scalenodinium, Fensome et al., 2016b, p.64.
Type: Fensome et al., 2016b, pl.12, fig.15, as Scalenodinium scalenum.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description Fensome et al., 2016b:
Etymology. The name is from the Latin scalenus, meaning unequal, uneven, odd, in reference to the unequal variation in apical and antapical development.
Description. Pericoel elongate, with an apical horn that is acuminate to rounded distally and generally a rounded antapex, although the latter may be extended into a short protuberance. When the endocyst is present, the cyst is bicavate. Cingulum present or faintly expressed. Periarchaeopyle intercalary, generally with formula I2a, and with a free operculum. The hexa 2a plate is stenodeltaform. In some specimens, the apparent loss of the apical area (Plate 12, figs 16–19) or of other intercalary plates besides the 2a (Plate 12, fig. 15) indicates a compound and/or combination archaeopyle.
Remarks. Scalenodinium differs from Isabelidinium in having a stenodeltaform, rather than a lati- to iso-omega-form 2a plate. Palaeocystodinium, which like Scalenodinium has a stenodeltaform 2a plate, differs from the latter genus in always having more or less apical and antapical horns and a periarchaeopyle that is always formed from the loss of a single plate, the 2a plate, rather than several plates as in Scalenodinium.