Back
Selenopemphix tholus
Selenopemphix tholus (Bradford, 1975, p.3072,3074, figs.17–22) Head, 1996b, p.1231.
Originally Omanodinium, subsequently Protoperidinium subgenus Protoperidinium section Selenopemphix (combination not validly published), thirdly (and now) Selenopemphix. This combination was not validly published in Lentin and Williams (1989, p.333), since these authors did not intend to propose it.
Holotype: Bradford, 1975, fig.17.
Age: Holocene.
Original diagnosis: Bradford, 1975, p.3072
Cyst pentagonal in ambitus, circular, ovoidal, or reniforme in polar view. Epitract and hypotract of similar size. Epitract with or without apical horns or wall thickening; flanks of epitract concave, apex domed or conical. Hypotract with or without two antapical horns or antapical wall thickenings; phragma concave. Cingular zone much broader than epitract or hypotract; cingulum extremely narrow. Sulcus distinct. Large, hoof-shaped intercalary archaeopyle. Phragma usually smooth and thin.
Dimensions: Holotype: Length 50 µm, lateral breadth 68 µm, archaeopyle heigth 46 µm, width 24 µm.
Original description: Bradford, 1975, p.3072
The ambitus has the characteristic peridinoid outline. The epitract and hypotract are of similar size. A dome-shaped epitract is characteristic; however, some forms are often more conical in the apical region. The latter may develop into a small apical horn or an internal wall thickening or both. The lower flanks of the epitract are distally concave and broaden rapidly into the cingular zone. Immediately below the narrow cingular zone, the hypotract shows a marked reduction in breadth with the concave flanks tapering gradually antapically.
Originally Omanodinium, subsequently Protoperidinium subgenus Protoperidinium section Selenopemphix (combination not validly published), thirdly (and now) Selenopemphix. This combination was not validly published in Lentin and Williams (1989, p.333), since these authors did not intend to propose it.
Holotype: Bradford, 1975, fig.17.
Age: Holocene.
Original diagnosis: Bradford, 1975, p.3072
Cyst pentagonal in ambitus, circular, ovoidal, or reniforme in polar view. Epitract and hypotract of similar size. Epitract with or without apical horns or wall thickening; flanks of epitract concave, apex domed or conical. Hypotract with or without two antapical horns or antapical wall thickenings; phragma concave. Cingular zone much broader than epitract or hypotract; cingulum extremely narrow. Sulcus distinct. Large, hoof-shaped intercalary archaeopyle. Phragma usually smooth and thin.
Dimensions: Holotype: Length 50 µm, lateral breadth 68 µm, archaeopyle heigth 46 µm, width 24 µm.
Original description: Bradford, 1975, p.3072
The ambitus has the characteristic peridinoid outline. The epitract and hypotract are of similar size. A dome-shaped epitract is characteristic; however, some forms are often more conical in the apical region. The latter may develop into a small apical horn or an internal wall thickening or both. The lower flanks of the epitract are distally concave and broaden rapidly into the cingular zone. Immediately below the narrow cingular zone, the hypotract shows a marked reduction in breadth with the concave flanks tapering gradually antapically.