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Hemisphaeridium
From Fensome et al., 2019:
Hemisphaeridium, Bujak in Bujak et al., 1980, p.56.
Type: Bujak et al., 1980, pl.15, fig.7, as Hemisphaeridium fenestratum.
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Original description: [Bujak in Bujak, 1980]:
Description:
Chorate cysts with a spherical, ovoidal, or ellipsoidal central body and a smooth, granulate, or reticulate periphragm. Numerous processes are arranged in intratabular complexes. Processes slender, tubiform, and open distally. Process complexes annulate or soleate on the apical, precingular, postcingular, antapical, posterior intercalary, and posterior sulcal paraplates; additional processes are sometimes present within the complexes. The paracingular process complexes are arcuate or linear. The processes forming a process complex are united distally by a membrane or trabeculate network.
Processes of adjacent complexes are occasionally connected by distal trabeculae or membranes.
Paratabulation 4`, 6", 6c, 6```, 1p, 1````, 1ps. Process complexes may be absent from some paraplates.
Archaeopyle epicystal, formed by the detachment of the apical and precingular paraplates
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Modified description:
Stover and Williams, 1987, p. 121:
Synopsis:
Cysts skolochorate, body subspherical to ellipsoidal and bearing intratabular process complexes; paracingular process complexes arcuate or linear, others annulate or soleate; components of process complexes united distally by a membrane or a trabecular network; adjacent complexes occasionally connected distally; process complexes indicate a paratabulation formula of 4`, 6", 6c, 6```, 1p, 1````, 1 ps; archeopyle epicystal, type [tAtP].
Description:
Shape: Skolochorate, body subspherical to ellipsoidal.
Wall relationships: Uncertain, probably undifferentiated autophragm.
Wall features: No parasutural features. Cyst bears intratabular process complexes whose individual stalks are joined distally by a membrane or trabecular network. Additional processes may occur within the process complexes and occasionally adjacent complexes are connected distally. Process complexes annular or soleate, except the cingular ones.
Archeopyle: Epicystal, type [tAtP]; whether paraplates of the operculum are separate or remain together is not stated in description.
Paratabulation: Indicated by intratabular process complexes; gonyaulacacean, formula: 4`, 6", 6c, 6```, 1 p, 1````, 1 ps.
Paracingulum: Indicated by six arcuate or linear process complexes.
Parasulcus: Apparently indicated by posterior sulcal process complex only.
Size: Intermediate; 55 µm to about 65 µm in diameter, including process complexes.
Affinities:
The presence of process complexes serves to separate Hemisphaeridium from the following genera, all of which have [tAtP] type archeopyles and parasutural features: Ctenidodinium Deflandre 1938 emended Woollam 1983, Dichadogonyaulax Sarjeant in Davey et al. 1966 emended Woollam, 1983, Dinopterygium Deflandre 1935 emended Stover and Evitt 1978, Heteraulacacysta Drugg and Loeblich 1967 emended Bujak in Bujak et al. 1980, and Korystocysta Woollam 1983. Hemisphaeridium differs from Polysphaeridium Davey and Williams in Davey et al. 1966 emended Bujak et al. 1980 in having process complexes rather than nontabular processes, and in lacking clusters of intratabular processes which are not connected distally.
Hemisphaeridium, Bujak in Bujak et al., 1980, p.56.
Type: Bujak et al., 1980, pl.15, fig.7, as Hemisphaeridium fenestratum.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Bujak in Bujak, 1980]:
Description:
Chorate cysts with a spherical, ovoidal, or ellipsoidal central body and a smooth, granulate, or reticulate periphragm. Numerous processes are arranged in intratabular complexes. Processes slender, tubiform, and open distally. Process complexes annulate or soleate on the apical, precingular, postcingular, antapical, posterior intercalary, and posterior sulcal paraplates; additional processes are sometimes present within the complexes. The paracingular process complexes are arcuate or linear. The processes forming a process complex are united distally by a membrane or trabeculate network.
Processes of adjacent complexes are occasionally connected by distal trabeculae or membranes.
Paratabulation 4`, 6", 6c, 6```, 1p, 1````, 1ps. Process complexes may be absent from some paraplates.
Archaeopyle epicystal, formed by the detachment of the apical and precingular paraplates
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Modified description:
Stover and Williams, 1987, p. 121:
Synopsis:
Cysts skolochorate, body subspherical to ellipsoidal and bearing intratabular process complexes; paracingular process complexes arcuate or linear, others annulate or soleate; components of process complexes united distally by a membrane or a trabecular network; adjacent complexes occasionally connected distally; process complexes indicate a paratabulation formula of 4`, 6", 6c, 6```, 1p, 1````, 1 ps; archeopyle epicystal, type [tAtP].
Description:
Shape: Skolochorate, body subspherical to ellipsoidal.
Wall relationships: Uncertain, probably undifferentiated autophragm.
Wall features: No parasutural features. Cyst bears intratabular process complexes whose individual stalks are joined distally by a membrane or trabecular network. Additional processes may occur within the process complexes and occasionally adjacent complexes are connected distally. Process complexes annular or soleate, except the cingular ones.
Archeopyle: Epicystal, type [tAtP]; whether paraplates of the operculum are separate or remain together is not stated in description.
Paratabulation: Indicated by intratabular process complexes; gonyaulacacean, formula: 4`, 6", 6c, 6```, 1 p, 1````, 1 ps.
Paracingulum: Indicated by six arcuate or linear process complexes.
Parasulcus: Apparently indicated by posterior sulcal process complex only.
Size: Intermediate; 55 µm to about 65 µm in diameter, including process complexes.
Affinities:
The presence of process complexes serves to separate Hemisphaeridium from the following genera, all of which have [tAtP] type archeopyles and parasutural features: Ctenidodinium Deflandre 1938 emended Woollam 1983, Dichadogonyaulax Sarjeant in Davey et al. 1966 emended Woollam, 1983, Dinopterygium Deflandre 1935 emended Stover and Evitt 1978, Heteraulacacysta Drugg and Loeblich 1967 emended Bujak in Bujak et al. 1980, and Korystocysta Woollam 1983. Hemisphaeridium differs from Polysphaeridium Davey and Williams in Davey et al. 1966 emended Bujak et al. 1980 in having process complexes rather than nontabular processes, and in lacking clusters of intratabular processes which are not connected distally.