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Avellodinium
From Williams et al., 2017:
[Avellodinium, Duxbury, 1977, p. 24; Emendations: Backhouse, 1988, p. 75
tax. jr. synonym of Callaiosphaeridium Davey and Williams, 1966, according to Below, 1981. Lentin and Williams, 1981, retained Avellodinium as a separate genus; Lentin and Williams, 1985, retained Avellodiniuum as a separate genus.
Type species: Avellodinium falsificum, Duxbury, 1977 (pl.5, figs.1–2)]
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Original description: [Duxbury, 1977]:
Diagnosis:
Chorate cysts, ellipsoidal, bearing numerous, slender gonal processes, which are proximally connected along body sutures by low crests. Distally, the processes trifurcate, subsequently bifurcating once or twice. Cingulum laevo-rotatory, sulcus broad. Tabulation 3`, 6", ?6c, 5```, 1-2s, 1pv, 1````. Archeopyle epitractal.
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Modified description:
Stover and Williams, 1987, p. 33:
Synopsis:
Cysts skolochorate, body subspherical, bearing gonal processes, processes joined proximally by parasutural septa; primary branching of process tips trifurcate, subsequent branching bifurcate; paratabulation gonyaulacacean, indicated by parasutural septa; archeopyle epicystal, type (tAtP).
Description:
Shape: Body subspherical.
Wall relationships: Endophragm and periphragm appressed between processes. Slight separation may occur beneath parasutural features.
Wall features: Parasutural septa connect bases of gonal processes. Branching of process tips primarily trifurcate, secondarily bifurcate; periphragm smooth or ornamented with features of low relief.
Archeopyle: Epicystal, combined apical and precingular, type [tAtPl; operculum free.
Paratabulation: Indicated by parasutural ridges and gonal processes; gonyaulacacean, formula: 3`-?4`, 6", ?6c, 5-?6```,1````,1-3s.
Paracingulum: Indicated by parasutural features and processes.
Parasulcus: Outlined by parasutural features; apparently confined to hypocyst; some sulcal paraplates may be delimited.
Size: Intermediate, overall size about 50 µm to 90 µm.
Affinities:
Avellodinium differs from Spiniterites Mantell 1850 emended Sarjeant 1970 in having an epicystal, rather than a precingular archeopyle. The presence of gonal processes with trifurcate bps distinguishes Avellodinium from other genera having epicystal type [tAtP] archeopyles except for Callaiosphaeridium. The latter has tubiform intratabular cingular processes.
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Emended description:
Backhouse, 1988:
Diagnosis:
Avellodinium is herein emended to include species with long, dichotomously branched intergonal processes similar in size and shape to the trifurcate gonal processes. The number of paraplates in the apical series is emended from 3 to 3 or 4.
[Avellodinium, Duxbury, 1977, p. 24; Emendations: Backhouse, 1988, p. 75
tax. jr. synonym of Callaiosphaeridium Davey and Williams, 1966, according to Below, 1981. Lentin and Williams, 1981, retained Avellodinium as a separate genus; Lentin and Williams, 1985, retained Avellodiniuum as a separate genus.
Type species: Avellodinium falsificum, Duxbury, 1977 (pl.5, figs.1–2)]
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Original description: [Duxbury, 1977]:
Diagnosis:
Chorate cysts, ellipsoidal, bearing numerous, slender gonal processes, which are proximally connected along body sutures by low crests. Distally, the processes trifurcate, subsequently bifurcating once or twice. Cingulum laevo-rotatory, sulcus broad. Tabulation 3`, 6", ?6c, 5```, 1-2s, 1pv, 1````. Archeopyle epitractal.
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Modified description:
Stover and Williams, 1987, p. 33:
Synopsis:
Cysts skolochorate, body subspherical, bearing gonal processes, processes joined proximally by parasutural septa; primary branching of process tips trifurcate, subsequent branching bifurcate; paratabulation gonyaulacacean, indicated by parasutural septa; archeopyle epicystal, type (tAtP).
Description:
Shape: Body subspherical.
Wall relationships: Endophragm and periphragm appressed between processes. Slight separation may occur beneath parasutural features.
Wall features: Parasutural septa connect bases of gonal processes. Branching of process tips primarily trifurcate, secondarily bifurcate; periphragm smooth or ornamented with features of low relief.
Archeopyle: Epicystal, combined apical and precingular, type [tAtPl; operculum free.
Paratabulation: Indicated by parasutural ridges and gonal processes; gonyaulacacean, formula: 3`-?4`, 6", ?6c, 5-?6```,1````,1-3s.
Paracingulum: Indicated by parasutural features and processes.
Parasulcus: Outlined by parasutural features; apparently confined to hypocyst; some sulcal paraplates may be delimited.
Size: Intermediate, overall size about 50 µm to 90 µm.
Affinities:
Avellodinium differs from Spiniterites Mantell 1850 emended Sarjeant 1970 in having an epicystal, rather than a precingular archeopyle. The presence of gonal processes with trifurcate bps distinguishes Avellodinium from other genera having epicystal type [tAtP] archeopyles except for Callaiosphaeridium. The latter has tubiform intratabular cingular processes.
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Emended description:
Backhouse, 1988:
Diagnosis:
Avellodinium is herein emended to include species with long, dichotomously branched intergonal processes similar in size and shape to the trifurcate gonal processes. The number of paraplates in the apical series is emended from 3 to 3 or 4.