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Morkallacysta
From Williams et al., 2017:
[Morkallacysta, Harris, 1974, p. 163
Tax. jr. syn. of Palaeoperidinium Deflandre, 1935, according to Lentin and Williams, 1976. Stover and Evitt, 1978, retained Morkallacysta as a separate genus.
Type species: Morkallacysta pyramidalis Harris, 1974 (pl.1, fig.5)]
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Original description: [Harris, 1974]:
Description:
Non-cavate dinoflagellate cysts of strongly peridinioid form with prominent apical and antapical horns. Helicoid girdle strongly marked. Archeopyle triangular with attached operculum. Cysts lacking tabulation and ornament.
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Modified description:
Stover and Evitt, 1978, p. 113:
Synopsis:
Cysts proximate, compressed peridinioid; apical and antapical horns prominent; autophragm commonly folded; indications of paratabulation weakly developed. Archeopyle apparently intercalary; Type uncertain, probably Type I, possibly 3I.
Description:
Shape: Compressed peridinioid; apical and antapical horns prominent.
Wall Relationships: Autophragm only.
Wall Features: Autophragm smooth to scabrate.
Paratabulation: Indicated mainly by paracingulum and archeopyle; almost always obscured because of folding.
Archeopyle: Probably intercalary; type uncertain, probably Type I, possibly 3I.
Paracingulum: Indicated by low, parallel, transverse ridges delimiting a shallow concavity.
Parasulcus: Not indicated or weakly expressed as a shallow depression on the hypocyst.
Size: Intermediate.
Affinities:
Morkallacysta differs from Deflandrea in having an autophragm only, rather than an endophragm and periphragm, and from Lejeunia in having well-developed apical and antapical horns.
[Morkallacysta, Harris, 1974, p. 163
Tax. jr. syn. of Palaeoperidinium Deflandre, 1935, according to Lentin and Williams, 1976. Stover and Evitt, 1978, retained Morkallacysta as a separate genus.
Type species: Morkallacysta pyramidalis Harris, 1974 (pl.1, fig.5)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Harris, 1974]:
Description:
Non-cavate dinoflagellate cysts of strongly peridinioid form with prominent apical and antapical horns. Helicoid girdle strongly marked. Archeopyle triangular with attached operculum. Cysts lacking tabulation and ornament.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt, 1978, p. 113:
Synopsis:
Cysts proximate, compressed peridinioid; apical and antapical horns prominent; autophragm commonly folded; indications of paratabulation weakly developed. Archeopyle apparently intercalary; Type uncertain, probably Type I, possibly 3I.
Description:
Shape: Compressed peridinioid; apical and antapical horns prominent.
Wall Relationships: Autophragm only.
Wall Features: Autophragm smooth to scabrate.
Paratabulation: Indicated mainly by paracingulum and archeopyle; almost always obscured because of folding.
Archeopyle: Probably intercalary; type uncertain, probably Type I, possibly 3I.
Paracingulum: Indicated by low, parallel, transverse ridges delimiting a shallow concavity.
Parasulcus: Not indicated or weakly expressed as a shallow depression on the hypocyst.
Size: Intermediate.
Affinities:
Morkallacysta differs from Deflandrea in having an autophragm only, rather than an endophragm and periphragm, and from Lejeunia in having well-developed apical and antapical horns.