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Holmwoodinium
From Williams et al., 2017:
[Holmwoodinium, Batten, 1985, p. 432
Type species: Holmwoodinium notatum, Batten, 1985 (text-figs.3D,5K–L)]
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Original description: [Batten, 1985]:
Description:
A small, thin-walled, smooth or weakly sculptured, ovoidal peridiniinean cyst lacking any prolongations of the autophragm but very rarely with a suggestion of two antapical lobes. Nature of folding and crumpling suggests that the wall is probably two-layered but there is no obvious separation of endophragm from periphragm; total thickness 1 µm or less.
Archeopyle involves all of the apical and intercalary paraplates but is generally poorly delineated and often appears as a thin, degraded, damaged area.
Paracingulum normally clearly visible but evidence of paratabulation is usually lacking and at best sketchy
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Modified description:
Stover and Williams, 1987, p. 123:
Synopsis:
Cysts proximate, outline subcircular, apex commonly missing; autophragm smooth to finely ornamented; archeopyle type [tAtl]; except for paracingulum and archeopyle, other indications of paracingulum lacking.
Description:
Shape: Outline subcircular, apex commonly absent; minor folding rarely distorts outline severely.
Wall relationships: Autophragm only or if two-layered, separation of individual layers indistinct.
Wall features: No parasutural features indicating paraplates or obvious projections; wall thin, smooth to finely ornamented.
Archeopyle: Type [tAtl], stated as being "generally poorly delineated and often appears as a thin, degraded, damaged area" (Batten, 1985, p. 432).
Paratabulation: Indicated by archeopyle and paracingulum when both are evident.
Paracingulum: Commonly evident; expressed by low, transverse crests and generally slight indentation.
Parasulcus: Not indicated.
Size: Small, overall size about 30 µm to 40 µm.
Affinities:
Holmwoodinium differs from Saeptodinium Harris 1974 in having a [tAtl] archeopyle rather than a [A313P]@ archeopyle. Ascodinium Cookson and Eisenack 1960; emended Helenes 1983, which also has a [tAtl] archeopyle, has two distinct wall layers and may be conspicuously cavate.
[Holmwoodinium, Batten, 1985, p. 432
Type species: Holmwoodinium notatum, Batten, 1985 (text-figs.3D,5K–L)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Batten, 1985]:
Description:
A small, thin-walled, smooth or weakly sculptured, ovoidal peridiniinean cyst lacking any prolongations of the autophragm but very rarely with a suggestion of two antapical lobes. Nature of folding and crumpling suggests that the wall is probably two-layered but there is no obvious separation of endophragm from periphragm; total thickness 1 µm or less.
Archeopyle involves all of the apical and intercalary paraplates but is generally poorly delineated and often appears as a thin, degraded, damaged area.
Paracingulum normally clearly visible but evidence of paratabulation is usually lacking and at best sketchy
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 123:
Synopsis:
Cysts proximate, outline subcircular, apex commonly missing; autophragm smooth to finely ornamented; archeopyle type [tAtl]; except for paracingulum and archeopyle, other indications of paracingulum lacking.
Description:
Shape: Outline subcircular, apex commonly absent; minor folding rarely distorts outline severely.
Wall relationships: Autophragm only or if two-layered, separation of individual layers indistinct.
Wall features: No parasutural features indicating paraplates or obvious projections; wall thin, smooth to finely ornamented.
Archeopyle: Type [tAtl], stated as being "generally poorly delineated and often appears as a thin, degraded, damaged area" (Batten, 1985, p. 432).
Paratabulation: Indicated by archeopyle and paracingulum when both are evident.
Paracingulum: Commonly evident; expressed by low, transverse crests and generally slight indentation.
Parasulcus: Not indicated.
Size: Small, overall size about 30 µm to 40 µm.
Affinities:
Holmwoodinium differs from Saeptodinium Harris 1974 in having a [tAtl] archeopyle rather than a [A313P]@ archeopyle. Ascodinium Cookson and Eisenack 1960; emended Helenes 1983, which also has a [tAtl] archeopyle, has two distinct wall layers and may be conspicuously cavate.