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Boreocysta
From Fensome et al., 2019:
Boreocysta, Stover and Evitt, 1978, p.22–23.
Emendation: Århus, 1992, p.306.
Type: Wiggins, 1969, pl.2, figs.1–2, as Omatia butticula.
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Original description: [Stover and Evitt, 1978]:
Synopsis:
Cysts holocavate, elongate ellipsoidal with prominent apical horn formed by ectophragm; ectocoel with slender simple or bifurcate processes; paratabulation indicated by archeopyle, latter apical, Type (tA)a.
Description:
Shape: Autocyst elongate ellipsoidal; ectocyst shape approximates that of autocyst, except apically, where former forms prominent apical horn.
Wall relationships: Holocavate, autophragm and ectophragm clearly separated.
Wall features: No parasutural features; area between wall layers with slender, simple or bifurcate processes that are more numerous on polar areas, but not necessarily on apical horn.
Paratabulation: Indicated by archeopyle only.
Archeopyle: Apical, Type (tA)a; principal archeopyle suture zigzag; operculum apparently normally attached.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Large.
Affinities:
Boreocysta differs from Gardodinium in being elongate ellipsoidal rather than subspherical, and in having a concentration of processes in the polar areas. Such concentrations have not been reported in specimens of Gardodinium.
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Emended description:
Arhus, 1992:
Diagnosis:
Large elongate ellipsoidal autocysts. Holocavate, but variable potential for preservation of the ectophragm. Ectocoel with slender simple or furcating processes. Paratabulation indicated by archeopyle, latter apical, type (tA).
Remarks:
The synopsis of Stover & Evitt (1978) is changed to include species without preserved ectophragm and thus unknown development of this in the apical area. The processes are not necessarily concentrated in the polar areas and may be branched in a more complex way than indicated by Stover and Evitt.
Affinities:
The genus Carnarvonodinium Parker 1988 with two species described from offshore northwestern Australia is similar, but has a short apical horn formed by the autophragm. Peridictyocysta Cookson and Eisenack 1974 has much more regularly arranged and well developed processes and trabeculae. Prolixosphaeridium Davey et al. 1966 emend. Davey 1969 has processes that usually taper distally and are closed. Representatives of this genus from the Norwegian shelf are much smaller than the species here in question.
Boreocysta, Stover and Evitt, 1978, p.22–23.
Emendation: Århus, 1992, p.306.
Type: Wiggins, 1969, pl.2, figs.1–2, as Omatia butticula.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Stover and Evitt, 1978]:
Synopsis:
Cysts holocavate, elongate ellipsoidal with prominent apical horn formed by ectophragm; ectocoel with slender simple or bifurcate processes; paratabulation indicated by archeopyle, latter apical, Type (tA)a.
Description:
Shape: Autocyst elongate ellipsoidal; ectocyst shape approximates that of autocyst, except apically, where former forms prominent apical horn.
Wall relationships: Holocavate, autophragm and ectophragm clearly separated.
Wall features: No parasutural features; area between wall layers with slender, simple or bifurcate processes that are more numerous on polar areas, but not necessarily on apical horn.
Paratabulation: Indicated by archeopyle only.
Archeopyle: Apical, Type (tA)a; principal archeopyle suture zigzag; operculum apparently normally attached.
Paracingulum: Not indicated.
Parasulcus: Not indicated.
Size: Large.
Affinities:
Boreocysta differs from Gardodinium in being elongate ellipsoidal rather than subspherical, and in having a concentration of processes in the polar areas. Such concentrations have not been reported in specimens of Gardodinium.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Arhus, 1992:
Diagnosis:
Large elongate ellipsoidal autocysts. Holocavate, but variable potential for preservation of the ectophragm. Ectocoel with slender simple or furcating processes. Paratabulation indicated by archeopyle, latter apical, type (tA).
Remarks:
The synopsis of Stover & Evitt (1978) is changed to include species without preserved ectophragm and thus unknown development of this in the apical area. The processes are not necessarily concentrated in the polar areas and may be branched in a more complex way than indicated by Stover and Evitt.
Affinities:
The genus Carnarvonodinium Parker 1988 with two species described from offshore northwestern Australia is similar, but has a short apical horn formed by the autophragm. Peridictyocysta Cookson and Eisenack 1974 has much more regularly arranged and well developed processes and trabeculae. Prolixosphaeridium Davey et al. 1966 emend. Davey 1969 has processes that usually taper distally and are closed. Representatives of this genus from the Norwegian shelf are much smaller than the species here in question.