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Ginginodinium flexidentatum
From Fensome et al., 2019:
Ginginodinium flexidentatum Fensome et al., 2016b, p.45–46, pl.7, figs.5–11. Holotype: Fensome et al., 2016b, pl.7, fig.11. Age: last occurrence, late Ypresian.
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Original description Fensome et al., 2016b:
Holotype. Plate 7, fig. 11, from a cuttings sample at 1815–1825 m in Bjarni O-82, GSC type collection no. 138070, sample P39715, slide 01, co-ordinates 3.6 × 102.8, England Finder C32/4. Pericyst length 84 μm, width 73 μm, endocyst length 61 μm, width 67 μm, length of processes up to 2.5 μm. The age determined for the sample from which the holotype was recovered is early Ypresian.
Etymology. The epithet is from the Latin flexibilis, meaning bendable and dentatus, meaning toothed or pointed.
Diagnosis. A species of Ginginodinium with one or more lateral horns or bulges, a flexible folded wall, and no clearly demarked cingulum. The ornament is variable but typically denticulate.
Description. Pericyst outline pentagonal, with a well-developed apical and two antapical horns, one of which is slightly shorter than the other, and two lateral protuberances. Generally cornucavate but can, in part or whole, be circumcavate. The endocyst is pentagonal. Pericyst ornamentation varies from finely perforate to verrucate to bearing processes. The archaeopyle involves the loss of the 2a plate, which remains attached to the 4´´ plate, and sometimes the partial detachment of the 1a and 3a plates. One margin of the cingulum is commonly indicated by a fold.
Size. Pericyst length 61–87 μm (mean 73 μm), pericyst width 56–73 μm (mean 63 μm), endocyst length 43–61 μm (mean 51 μm), width 49– 67 μm (mean 53 μm), process length up to about 2.5 μm.
Age. LO: late Ypresian.
Remarks. The shapes of the pericyst and endocyst are relatively stable in Ginginodinium? flexidentatum, but there are differences between specimens in degree of cavation, which can range from cornucavate to narrowly circumcavate. There are also variations in the shape of the horns, especially the apical: this is generally rounded distally but may be acuminate. The antapical horns are acuminate to rounded distally; the lateral horns are primarily just protuberances. Pericyst ornamentation is variable, sometimes even on the same specimen. The periphragm can be perforated and ornamented with small verrucae and processes, the latter of variable length. Processes are slender and distally bifid. This species is included in Ginginodinium only provisionally because of the uncertainty over the archaeopyle.
Ginginodinium flexidentatum Fensome et al., 2016b, p.45–46, pl.7, figs.5–11. Holotype: Fensome et al., 2016b, pl.7, fig.11. Age: last occurrence, late Ypresian.
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Original description Fensome et al., 2016b:
Holotype. Plate 7, fig. 11, from a cuttings sample at 1815–1825 m in Bjarni O-82, GSC type collection no. 138070, sample P39715, slide 01, co-ordinates 3.6 × 102.8, England Finder C32/4. Pericyst length 84 μm, width 73 μm, endocyst length 61 μm, width 67 μm, length of processes up to 2.5 μm. The age determined for the sample from which the holotype was recovered is early Ypresian.
Etymology. The epithet is from the Latin flexibilis, meaning bendable and dentatus, meaning toothed or pointed.
Diagnosis. A species of Ginginodinium with one or more lateral horns or bulges, a flexible folded wall, and no clearly demarked cingulum. The ornament is variable but typically denticulate.
Description. Pericyst outline pentagonal, with a well-developed apical and two antapical horns, one of which is slightly shorter than the other, and two lateral protuberances. Generally cornucavate but can, in part or whole, be circumcavate. The endocyst is pentagonal. Pericyst ornamentation varies from finely perforate to verrucate to bearing processes. The archaeopyle involves the loss of the 2a plate, which remains attached to the 4´´ plate, and sometimes the partial detachment of the 1a and 3a plates. One margin of the cingulum is commonly indicated by a fold.
Size. Pericyst length 61–87 μm (mean 73 μm), pericyst width 56–73 μm (mean 63 μm), endocyst length 43–61 μm (mean 51 μm), width 49– 67 μm (mean 53 μm), process length up to about 2.5 μm.
Age. LO: late Ypresian.
Remarks. The shapes of the pericyst and endocyst are relatively stable in Ginginodinium? flexidentatum, but there are differences between specimens in degree of cavation, which can range from cornucavate to narrowly circumcavate. There are also variations in the shape of the horns, especially the apical: this is generally rounded distally but may be acuminate. The antapical horns are acuminate to rounded distally; the lateral horns are primarily just protuberances. Pericyst ornamentation is variable, sometimes even on the same specimen. The periphragm can be perforated and ornamented with small verrucae and processes, the latter of variable length. Processes are slender and distally bifid. This species is included in Ginginodinium only provisionally because of the uncertainty over the archaeopyle.