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Parvocysta
From Williams et al., 2017:
[Parvocysta, Bjaerke, 1980, p. 59–60, 62
Tax. sr. syn.: Dodekovia, according to Below (1987a, p.113) — however, Lentin and Williams (1989, p.284) retained Parvocysta.
Type species: Parvocysta bullula, Bjaerke, 1980 (pl.1, figs.4–5)]
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Original description: [Bjærke, 1980]:
Diagnosis:
Proximate dinoflagellate cysts. Cyst wall formed by autophragm only. Archaeopyle intercalary, outline hexagonal with posterior and anterior angulations (geniculate). Paratabulation except for archaeopyle not evident. Cyst outline subcircular to roughly pentagonal. With or without apical and lateral horns, antapical horn not developed. Cyst surface smooth, scabrate or ornamented by spines. Paracingulum indicated by reduction or absence of ornamentation, shallow to deeply constricted.
Affinities:
Two genera with this (as in Parvocysta) type of archaeopyle have been described previously. Moesiodinium Antonescu 1974 and Broomea Cookson and Eisenack 1958; emend. Lentin and Williams 1976. Moesiodinium differs from Parvocysta by being cavate. The genus Broomea has been restricted to cysts with a long apical horn and an elongated, ellipsoidal outline, a shallow "girdle", and two antapical horns. The great difference in size between the species described here under Parvocysta and Broomea ramosa, the only species assigned to Broomea, must also be noted. Broomea ramosa may possibly be regarded as representing an extreme development of characters present in Parvocysta.
Parvocysta resembles Facetodinium Bjaerke 1980 but lacks the intratabular ornamentation seen in that genus. Size range, nature of autophragm and the outline and position of archaeopyle suggest that the two genera are closely related.
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Modified description:
Stover and Williams, 1987, p. 171:
Synopsis:
Cysts proximate, outline in dorsal-ventral view ovoidal to pentalobate with equatorial constriction; lobes may be reduced or attenuated into horns; ornamentation on autophragm varies from features of low relief to prominent spines; archaeopyle intercalary, type I, 2a bicamerate; operculum free.
Description:
Shape: Body flattened dorso-ventrally; outline in dorsal-ventral view ovoidal to pentalobate with slight to deep equatorial concavity. Lobes may be extended into horns.
Wall relationships: Autophragm only.
Wall features: Autophragm surface smooth, or with non-tabular features of low relief, or with spines.
Archaeopyle: Intercalary, type I, 2a bicamerate; operculum free.
Paratabulation: Indicated by archaeopyle and paracingulum only.
Paracingulum: Indicated by equatorial concavity; also by reduction or lack of ornamentation on other than smooth forms.
Parasulcus: Not indicated.
Size: Small to intermediate, length about 20 to 75 µm, usually less than 50 µm.
Affinities:
Parvocysta differs from Susadinium Dörhöfer and Davies, 1980 in lacking intratabular features, and from Broomea Cookson and Eisenack, 1958; emend. Lentin and Williams, 1976 in not having fibroid antapical appendages.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Parvocysta Bjaerke, 1980. Stover and Williams (1987, p.171) provided the following synopsis. Cysts proximate, outline in dorsal-ventral view ovoidal to pentalobate with equatorial constriction; lobes may be reduced or attenuated into horns; ornamentation on autophragm varies from features of low relief to prominent spines; archeopyle intercalary, type I, 2a bicamerate, operculum free.
[Parvocysta, Bjaerke, 1980, p. 59–60, 62
Tax. sr. syn.: Dodekovia, according to Below (1987a, p.113) — however, Lentin and Williams (1989, p.284) retained Parvocysta.
Type species: Parvocysta bullula, Bjaerke, 1980 (pl.1, figs.4–5)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Bjærke, 1980]:
Diagnosis:
Proximate dinoflagellate cysts. Cyst wall formed by autophragm only. Archaeopyle intercalary, outline hexagonal with posterior and anterior angulations (geniculate). Paratabulation except for archaeopyle not evident. Cyst outline subcircular to roughly pentagonal. With or without apical and lateral horns, antapical horn not developed. Cyst surface smooth, scabrate or ornamented by spines. Paracingulum indicated by reduction or absence of ornamentation, shallow to deeply constricted.
Affinities:
Two genera with this (as in Parvocysta) type of archaeopyle have been described previously. Moesiodinium Antonescu 1974 and Broomea Cookson and Eisenack 1958; emend. Lentin and Williams 1976. Moesiodinium differs from Parvocysta by being cavate. The genus Broomea has been restricted to cysts with a long apical horn and an elongated, ellipsoidal outline, a shallow "girdle", and two antapical horns. The great difference in size between the species described here under Parvocysta and Broomea ramosa, the only species assigned to Broomea, must also be noted. Broomea ramosa may possibly be regarded as representing an extreme development of characters present in Parvocysta.
Parvocysta resembles Facetodinium Bjaerke 1980 but lacks the intratabular ornamentation seen in that genus. Size range, nature of autophragm and the outline and position of archaeopyle suggest that the two genera are closely related.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Williams, 1987, p. 171:
Synopsis:
Cysts proximate, outline in dorsal-ventral view ovoidal to pentalobate with equatorial constriction; lobes may be reduced or attenuated into horns; ornamentation on autophragm varies from features of low relief to prominent spines; archaeopyle intercalary, type I, 2a bicamerate; operculum free.
Description:
Shape: Body flattened dorso-ventrally; outline in dorsal-ventral view ovoidal to pentalobate with slight to deep equatorial concavity. Lobes may be extended into horns.
Wall relationships: Autophragm only.
Wall features: Autophragm surface smooth, or with non-tabular features of low relief, or with spines.
Archaeopyle: Intercalary, type I, 2a bicamerate; operculum free.
Paratabulation: Indicated by archaeopyle and paracingulum only.
Paracingulum: Indicated by equatorial concavity; also by reduction or lack of ornamentation on other than smooth forms.
Parasulcus: Not indicated.
Size: Small to intermediate, length about 20 to 75 µm, usually less than 50 µm.
Affinities:
Parvocysta differs from Susadinium Dörhöfer and Davies, 1980 in lacking intratabular features, and from Broomea Cookson and Eisenack, 1958; emend. Lentin and Williams, 1976 in not having fibroid antapical appendages.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Parvocysta Bjaerke, 1980. Stover and Williams (1987, p.171) provided the following synopsis. Cysts proximate, outline in dorsal-ventral view ovoidal to pentalobate with equatorial constriction; lobes may be reduced or attenuated into horns; ornamentation on autophragm varies from features of low relief to prominent spines; archeopyle intercalary, type I, 2a bicamerate, operculum free.