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Trivalvadinium
From Williams et al., 2017:
[Trivalvadinium, Islam, 1983, p. 344, 346; Emendation: Khowaja-Ateequzzaman and Garg, 1995, p. 247-248.
Type species: Trivalvadinium formosum, Islam, 1983 (pl.4, fig.9)]
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Original description: [Islam, 1983]:
Description:
Cyst peridinioid and roundly pentagonal to subspherical; horns, if present, vestigial; laterally to dorsoventrally compressed; proximochorate; acavate to narrowly circumcavate when possessing two mildly ornamented phragma; numerous or relatively fewer nontabular processes, solid, tubular or thinly tubular; archeopyle intercalary type 3I/3I or 3I when an autocyst, operculum free, opercular pieces not found.
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Modified description:
Stover and Williams 1987, p. 219:
Synopsis:
Cysts proximochorate, compressed peridinioid to roundly pentagonal or subspherical; acavate, cornucavate or narrowly circumcavate; periphragm with sparse to numerous, solid or hollow, nontabular processes; archeopyle intercalary type 3I/3I, operculum free.
Description:
Shape: Compressed peridiniod to roundly pentagonal or subspherical; apical and both antapical horns short; any or all horns may be lacking.
Wall relationships: Acavate, cornucavate to narrowly circumcavate; lateral cavation may be discontinuous.
Wall features: Endophragm and periphragm thin, latter with sparse to numerous, solid or hollow, nontabular processes; processes occasionally
joined in pairs proximally.
Archeopyle: Intercalary type 3I/3I; opercular piece(s?) free, but not observed.
Paratabulation: Indicated by archeopyle only.
Parasulcus: Not indicated.
Size: Small to intermediate, length about 45 to 60 µm.
Affinities:
Trivalvadinium differs from Apectodinium (Costa and Downie 1976) Lentin and Williams 1977b and from Gerlachidium Benedek and Sarjeant 1981 in possessing a 3I rather than an I archeopyle.
Trithyrodinium Drugg 1967 emended Lentin and Williams 1976, which also has a 3I archeopyle, lacks processes unlike Trivalvadinium. Ginginodinium, Cookson and Eisenack 1960a emended Lentin and Williams 1976 typically shows indications of paratabulation in addition to the archeopyle.
[Trivalvadinium, Islam, 1983, p. 344, 346; Emendation: Khowaja-Ateequzzaman and Garg, 1995, p. 247-248.
Type species: Trivalvadinium formosum, Islam, 1983 (pl.4, fig.9)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Islam, 1983]:
Description:
Cyst peridinioid and roundly pentagonal to subspherical; horns, if present, vestigial; laterally to dorsoventrally compressed; proximochorate; acavate to narrowly circumcavate when possessing two mildly ornamented phragma; numerous or relatively fewer nontabular processes, solid, tubular or thinly tubular; archeopyle intercalary type 3I/3I or 3I when an autocyst, operculum free, opercular pieces not found.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams 1987, p. 219:
Synopsis:
Cysts proximochorate, compressed peridinioid to roundly pentagonal or subspherical; acavate, cornucavate or narrowly circumcavate; periphragm with sparse to numerous, solid or hollow, nontabular processes; archeopyle intercalary type 3I/3I, operculum free.
Description:
Shape: Compressed peridiniod to roundly pentagonal or subspherical; apical and both antapical horns short; any or all horns may be lacking.
Wall relationships: Acavate, cornucavate to narrowly circumcavate; lateral cavation may be discontinuous.
Wall features: Endophragm and periphragm thin, latter with sparse to numerous, solid or hollow, nontabular processes; processes occasionally
joined in pairs proximally.
Archeopyle: Intercalary type 3I/3I; opercular piece(s?) free, but not observed.
Paratabulation: Indicated by archeopyle only.
Parasulcus: Not indicated.
Size: Small to intermediate, length about 45 to 60 µm.
Affinities:
Trivalvadinium differs from Apectodinium (Costa and Downie 1976) Lentin and Williams 1977b and from Gerlachidium Benedek and Sarjeant 1981 in possessing a 3I rather than an I archeopyle.
Trithyrodinium Drugg 1967 emended Lentin and Williams 1976, which also has a 3I archeopyle, lacks processes unlike Trivalvadinium. Ginginodinium, Cookson and Eisenack 1960a emended Lentin and Williams 1976 typically shows indications of paratabulation in addition to the archeopyle.