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Selenopemphix alticinctum
Selenopemphix alticincta (Bradford, 1975, p.3070,3072, figs.23–28) Matsuoka, 1985a, p.52. Holotype: Bradford, 1975, figs.23–26; Fensome et al., 1993a, figs.1–4 — p.907. Originally Omanodinium, subsequently (and now) Selenopemphix. Head (1993, p.32), by considering Omanodinium to be a taxonomic junior synonym of Selenopemphix, effectively retained this species in Selenopemphix. Motile equivalent: Protoperidinium subinerme (Paulsen, 1904) Loeblich III, 1970, according to Bradford (1975, p.3070) and Matsuoka (1984b, p.2) — however, see Head (1996b, p.1215). Age: Holocene.
Original diagnosis: Bradford, 1975, p.3070: Omanodinium alticinctum
Cingulum broad, wide and deeply excavated, dividing epitract and hypotract almost equally. Epitract conical or dome-shaped with or without an apical horn or wall thickening at apex. Large intercalary archeopyle. Hypotract three-sided, tapering slightly antapically, with or without wall thickening at distal points. No antapical depression. Shallow, distinct sulcus; smooth-walled test. Acapsulate.
Original description: Bradford, 1975, p.3072: Omanodinium alticinctum
The genus is characterized by the broad girdle zone. The species is distinct in having a wide and deeply excavated cingulum which divides the test into equal or near-equal sections. In polar view, the cysts are circular or weakly dorsoventrally compressed. The epitract is conical or apically domed with concave surfaces, except near the apex, where some convexity is observed. Wall thickening is sometimes present apically. The anterior intercalary archeopyle is medium to large in size, but by viewing its overall shape, it probably only represents one plate. The hypotract tapers antapically to form a dorsoventrally flattened ridge, with rounded distal comers usually showing internal wall thickening. The wall edges of the hypotract are usually concave. The sulcal area is slightly depressed and forms a relatively wide break in the cingulum; this area is usually shaded with a light microverrucate ornament and a sulcal pore can often be recognized. Apart from the sulcal area, the test wall is smooth.
Size: Holotype: length 36 µm, breadth 39 µm, width of cingulum 6 µm, distance across antapical flange 14 µm. Other specimen: length 30 µm, breadth 33 µm, width of cingulum 6 µm, distance across antapical flange 12 µm.
Original diagnosis: Bradford, 1975, p.3070: Omanodinium alticinctum
Cingulum broad, wide and deeply excavated, dividing epitract and hypotract almost equally. Epitract conical or dome-shaped with or without an apical horn or wall thickening at apex. Large intercalary archeopyle. Hypotract three-sided, tapering slightly antapically, with or without wall thickening at distal points. No antapical depression. Shallow, distinct sulcus; smooth-walled test. Acapsulate.
Original description: Bradford, 1975, p.3072: Omanodinium alticinctum
The genus is characterized by the broad girdle zone. The species is distinct in having a wide and deeply excavated cingulum which divides the test into equal or near-equal sections. In polar view, the cysts are circular or weakly dorsoventrally compressed. The epitract is conical or apically domed with concave surfaces, except near the apex, where some convexity is observed. Wall thickening is sometimes present apically. The anterior intercalary archeopyle is medium to large in size, but by viewing its overall shape, it probably only represents one plate. The hypotract tapers antapically to form a dorsoventrally flattened ridge, with rounded distal comers usually showing internal wall thickening. The wall edges of the hypotract are usually concave. The sulcal area is slightly depressed and forms a relatively wide break in the cingulum; this area is usually shaded with a light microverrucate ornament and a sulcal pore can often be recognized. Apart from the sulcal area, the test wall is smooth.
Size: Holotype: length 36 µm, breadth 39 µm, width of cingulum 6 µm, distance across antapical flange 14 µm. Other specimen: length 30 µm, breadth 33 µm, width of cingulum 6 µm, distance across antapical flange 12 µm.