Back
Scalenodinium scalenum
From Fensome et al., 2019:
Scalenodinium scalenum Fensome et al., 2016b, p.64–65, pl.12, figs.15–20. Holotype: Fensome et al., 2016b, pl.12, fig.15. Age: last occurrence, Ypresian.
---------------------------------------------------------------------------------------------------
Original description Fensome et al., 2016b:
Holotype. Plate 12, fig. 15, from a cuttings sample at 2135–2145 m in Gilbert F-53, GSC type collection no. 137916, sample P39484, slide 01, co-ordinates 19.3 × 106.5, England Finder T37/4. Pericyst length 81 μm, width 31 μm. The age determined for the sample from which the holotype was recovered is Ypresian.
Etymology. The name is from the Latin scalenus, meaning unequal, uneven, odd, in reference to the unequal variation in apical and antapical development.
Description. A species of Scalenodinium with an elongate pericoel that has an apex bearing a well-developed, distally acuminate to rounded apical horn and an antapex that is generally rounded, though an antapical protuberance may occasionally be developed. When an endocyst is present, the cyst is bicavate. The pericyst is verrucate to granulate in the mid-dorsal and mid-ventral regions. A cingulum is rarely developed. Both pericyst and endocyst have walls that are, at the most, 1 μm thick. Periarchaeopyle intercalary, generally with formula I2a , operculum free. 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.
Size. Pericyst length 77–86 μm, pericyst width 38–56 μm, apical horn length 18–27 μm, apical horn maximum breadth 11–14 μm.
Age. LO: Ypresian.
Remarks. Scalenodinium scalenum shows some variation in the antapical region: although generally rounded antapically, some specimens have a prominent antapical horn that is more or less centrally located. The pericyst invariably has folds running across its surface. It is difficult to be specific about the nature of the archaeopyle since there is a common tendency for the apical polar area to break up. Thus this breakup could be interpreted to denote a compound or combination archaeopyle. Width and shape of the distal terminations of the horn or horns vary considerably.
Scalenodinium scalenum Fensome et al., 2016b, p.64–65, pl.12, figs.15–20. Holotype: Fensome et al., 2016b, pl.12, fig.15. Age: last occurrence, Ypresian.
---------------------------------------------------------------------------------------------------
Original description Fensome et al., 2016b:
Holotype. Plate 12, fig. 15, from a cuttings sample at 2135–2145 m in Gilbert F-53, GSC type collection no. 137916, sample P39484, slide 01, co-ordinates 19.3 × 106.5, England Finder T37/4. Pericyst length 81 μm, width 31 μm. The age determined for the sample from which the holotype was recovered is Ypresian.
Etymology. The name is from the Latin scalenus, meaning unequal, uneven, odd, in reference to the unequal variation in apical and antapical development.
Description. A species of Scalenodinium with an elongate pericoel that has an apex bearing a well-developed, distally acuminate to rounded apical horn and an antapex that is generally rounded, though an antapical protuberance may occasionally be developed. When an endocyst is present, the cyst is bicavate. The pericyst is verrucate to granulate in the mid-dorsal and mid-ventral regions. A cingulum is rarely developed. Both pericyst and endocyst have walls that are, at the most, 1 μm thick. Periarchaeopyle intercalary, generally with formula I2a , operculum free. 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.
Size. Pericyst length 77–86 μm, pericyst width 38–56 μm, apical horn length 18–27 μm, apical horn maximum breadth 11–14 μm.
Age. LO: Ypresian.
Remarks. Scalenodinium scalenum shows some variation in the antapical region: although generally rounded antapically, some specimens have a prominent antapical horn that is more or less centrally located. The pericyst invariably has folds running across its surface. It is difficult to be specific about the nature of the archaeopyle since there is a common tendency for the apical polar area to break up. Thus this breakup could be interpreted to denote a compound or combination archaeopyle. Width and shape of the distal terminations of the horn or horns vary considerably.