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Exochosphaeridium sp. b of prössl, 1990
Exochosphaeridium sp. B of Prössl, 1990
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Genus: Exochosphaeridium Davey et al., 1966
Type species: Exochosphaeridium phragmites Davey et al., 1966
Original description: Davey et al., 1966, p. 165
Diagnosis: Subspherical chorate cysts bearing numerous, commonly simple, closed processes. Apical process larger than normal processes and irregularly branched. Archaeopyle precingular.
Remarks: The processes are commonly acuminate, often joining proximally, but may be branched. Only rarely can an alignment of these processes be observed. The apical process makes orientation easy and indicates that the archaeopyle is precingular. Detached archaeopyle plates have been found and these show the characteristic precingular shape.
Stover and Evitt 1978, p. 154
Synopsis: Cysts skolochorate; body spherical with numerous nontabular, simple or branched, fibrous, typically solid processes; apical and occasionally, antapical processes wider, longer, or more irregularly branched than others; archeopyle precingular, Type P.
Modified description:
Shape: Body subspherical.
Wall relationships: Usually autophragm only; occasionally endophragm and periphragm discernible at the bases of processes.
Wall features: No parasutural features. Nontabular processes, simple or branched, solid, fibrous, tips acuminate or expanded distally; apical process and, less commonly, the antapical process may be wider, longer, or more irregularly branched than other processes. Surface between processes fibrous.
Paratabulation: Indicated by archeopyle only.
Archeopyle: Precingular, Type P (3"" only); operculum free.
Paracingulum: Not indicated, or indicated weakly by transverse alignment of some processes.
Parasulcus: Not indicated.
Size: Intermediate.
Affinities:
Stover and Evitt 1978, p. 154: Exochosphaeridium differs from Amphorosphaeridium in having solid, less complexly branched processes, except for generally wider or longer apical process. It differs from Operculodinium in having fibrous processes and a different apical process, which Operculodinium lacks. Retention of both Exochosphaeridium and Amphorosphaeridium seem dubious.
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Genus: Exochosphaeridium Davey et al., 1966
Type species: Exochosphaeridium phragmites Davey et al., 1966
Original description: Davey et al., 1966, p. 165
Diagnosis: Subspherical chorate cysts bearing numerous, commonly simple, closed processes. Apical process larger than normal processes and irregularly branched. Archaeopyle precingular.
Remarks: The processes are commonly acuminate, often joining proximally, but may be branched. Only rarely can an alignment of these processes be observed. The apical process makes orientation easy and indicates that the archaeopyle is precingular. Detached archaeopyle plates have been found and these show the characteristic precingular shape.
Stover and Evitt 1978, p. 154
Synopsis: Cysts skolochorate; body spherical with numerous nontabular, simple or branched, fibrous, typically solid processes; apical and occasionally, antapical processes wider, longer, or more irregularly branched than others; archeopyle precingular, Type P.
Modified description:
Shape: Body subspherical.
Wall relationships: Usually autophragm only; occasionally endophragm and periphragm discernible at the bases of processes.
Wall features: No parasutural features. Nontabular processes, simple or branched, solid, fibrous, tips acuminate or expanded distally; apical process and, less commonly, the antapical process may be wider, longer, or more irregularly branched than other processes. Surface between processes fibrous.
Paratabulation: Indicated by archeopyle only.
Archeopyle: Precingular, Type P (3"" only); operculum free.
Paracingulum: Not indicated, or indicated weakly by transverse alignment of some processes.
Parasulcus: Not indicated.
Size: Intermediate.
Affinities:
Stover and Evitt 1978, p. 154: Exochosphaeridium differs from Amphorosphaeridium in having solid, less complexly branched processes, except for generally wider or longer apical process. It differs from Operculodinium in having fibrous processes and a different apical process, which Operculodinium lacks. Retention of both Exochosphaeridium and Amphorosphaeridium seem dubious.