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Bianchina
From Williams et al., 2017:
[Bianchina, Schiøler, 2015, p. 408, 410
Type species: Bianchina hieroglyphica, Schiøler, 2015 (pl.1, figs.6–7)]
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Original description: [Schiøler, 2015]:
Description:
Subspherical to slightly biconical, dorsoventrally compressed, single-layered peridinioid cyst of intermediate to large size, possessing surface ornament that indicates the tabulation. The epicyst is sub-hemispherical in most specimens, slightly conical in rare cases. The hypocyst is smaller than the epicyst and slightly conical in most specimens, usually bearing a small antapical boss. The combination archaeopyle is formed by sutures between the three intercalary plates (1–3a) and the three mid-dorsal precingulars (3–5''). The operculum is compound with adnate opercular pieces. The attachment is adapical for the intercalary plates and adcingular for the precingular plates. The archaeopyle formula is 3Ia3Pa3–5′′.
Discussion/Affinities:
Bianchina resembles the peridinioid genera Laciniadinium, Saeptodinium and Luxadinium of the Palaeoperidinium complex of Evitt (1985 Evitt WR. 1985. Sporopollenin dinoflagellate cysts: their morphology and interpretation. Dallas: American Association of Stratigraphic Palynologists Foundation, p. 1–333.) in having a combination archaeopyle that involves the three intercalary plates and the three mid-dorsal precingular plates, but it differs from all these three genera in having a compound operculum with adnate opercular pieces and in having its tabulation clearly expressed by surface ornament. Laciniadinium has a simple operculum which is adnate along the precingular margin; the operculum of Saeptodinium is adnate, as is that of Laciniadinium but further incorporates the third apical plate. Luxadinium has a simple, free operculum. Ginginodinum also has a combination archaeopyle similar to that of Bianchina, with a compound operculum comprising three mid-dorsal precingulars and all three intercalary plates, but it differs in having a free operculum consisting of all three intercalary plates. Ginginodinium further differs in bearing spines or processes and in having a pentagonal peridinioid shape with apical, lateral and antapical horns as opposed to the subsphaerical shape of Bianchina. Diconodinium resembles Bianchina in having a conical hypocyst which is smaller than the epicyst, but differs in also having a conical epicyst and in either lacking an archaeopyle or, when present, having an adcingular adnate, simple, two-plate combination archaeopyle comprising precingular plate 4′′ and intercalary plate 2a. Diconodinium further differs from Bianchina in lacking tabulation except for the cingulum.
[Bianchina, Schiøler, 2015, p. 408, 410
Type species: Bianchina hieroglyphica, Schiøler, 2015 (pl.1, figs.6–7)]
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Original description: [Schiøler, 2015]:
Description:
Subspherical to slightly biconical, dorsoventrally compressed, single-layered peridinioid cyst of intermediate to large size, possessing surface ornament that indicates the tabulation. The epicyst is sub-hemispherical in most specimens, slightly conical in rare cases. The hypocyst is smaller than the epicyst and slightly conical in most specimens, usually bearing a small antapical boss. The combination archaeopyle is formed by sutures between the three intercalary plates (1–3a) and the three mid-dorsal precingulars (3–5''). The operculum is compound with adnate opercular pieces. The attachment is adapical for the intercalary plates and adcingular for the precingular plates. The archaeopyle formula is 3Ia3Pa3–5′′.
Discussion/Affinities:
Bianchina resembles the peridinioid genera Laciniadinium, Saeptodinium and Luxadinium of the Palaeoperidinium complex of Evitt (1985 Evitt WR. 1985. Sporopollenin dinoflagellate cysts: their morphology and interpretation. Dallas: American Association of Stratigraphic Palynologists Foundation, p. 1–333.) in having a combination archaeopyle that involves the three intercalary plates and the three mid-dorsal precingular plates, but it differs from all these three genera in having a compound operculum with adnate opercular pieces and in having its tabulation clearly expressed by surface ornament. Laciniadinium has a simple operculum which is adnate along the precingular margin; the operculum of Saeptodinium is adnate, as is that of Laciniadinium but further incorporates the third apical plate. Luxadinium has a simple, free operculum. Ginginodinum also has a combination archaeopyle similar to that of Bianchina, with a compound operculum comprising three mid-dorsal precingulars and all three intercalary plates, but it differs in having a free operculum consisting of all three intercalary plates. Ginginodinium further differs in bearing spines or processes and in having a pentagonal peridinioid shape with apical, lateral and antapical horns as opposed to the subsphaerical shape of Bianchina. Diconodinium resembles Bianchina in having a conical hypocyst which is smaller than the epicyst, but differs in also having a conical epicyst and in either lacking an archaeopyle or, when present, having an adcingular adnate, simple, two-plate combination archaeopyle comprising precingular plate 4′′ and intercalary plate 2a. Diconodinium further differs from Bianchina in lacking tabulation except for the cingulum.