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Dolichodinium
From Fensome et al., 2019:
Dolichodinium, Williams et al., 2015, p.303.
Type: Michoux, 1988, pl.7, figs.1–5, text-fig.12, as Wetzeliella uncinata.
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Original description: [Williams et al., 2015]:
Diagnosis:
Wetzelielloidean cysts with a hypersoleiform periarcheopyle and pericyst ornamentation that is conspicuously sutural to penitabular.
Description:
Shape: Dorso-ventral outline of pericyst rhomboidal to pentagonal, horns well developed except for right antapical which is considerably shorter than the left antapical. Dorso-ventral outline of endocyst rounded to quadrangular to occasionally pentagonal.
Wall structure: Periphragm thin, with processes sutural or penitabular, relatively short (e.g. up to 3 μm in Dolichodinium uncinatum and up to 7.5 μm in Dolichodinium conspicum), with tips blunt, capitate or aculeate distally and always free. Endophragm thin, usually smooth.
Pericoels: Cysts circumcavate, occasionally approaching cornucavate.
Tabulation: Delineated by sutural or penitabular processes on pericyst.
Archeopyle: Hypersoleiform. Periarcheopyle operculum generally attached along anterior margin and extending beyond anterior margin of endocyst in an apical direction. Endoarcheopyle with operculum attached anteriorly or free.
Furrows: Cingulum expressed by a single row of processes; sulcus delineated by processes.
Size: Large.
Affinities/Discussion:
Dolichodinium is the only known genus with a hypersoleiform archeopyle. Other wetzelielloidean genera with sutural and/or penitabular ornament are Castellodinium, Stichodinium, Vallodinium and Wilsonidium. Castellodinium, like Dolichodinium, has a perioperculum that is attached anteriorly, but the archeopyle is soleiform rather than hypersoleiform. Stichodinium has a latiepeliform archeopyle, Vallodinium has an equiepeliform archeopyle and Wilson-idium has a hyperepeliform archeopyle.
The holotype of Dolichodinium uncinatum has a pericyst length of 119 μm and a width of 128 μm.
Dolichodinium, Williams et al., 2015, p.303.
Type: Michoux, 1988, pl.7, figs.1–5, text-fig.12, as Wetzeliella uncinata.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Williams et al., 2015]:
Diagnosis:
Wetzelielloidean cysts with a hypersoleiform periarcheopyle and pericyst ornamentation that is conspicuously sutural to penitabular.
Description:
Shape: Dorso-ventral outline of pericyst rhomboidal to pentagonal, horns well developed except for right antapical which is considerably shorter than the left antapical. Dorso-ventral outline of endocyst rounded to quadrangular to occasionally pentagonal.
Wall structure: Periphragm thin, with processes sutural or penitabular, relatively short (e.g. up to 3 μm in Dolichodinium uncinatum and up to 7.5 μm in Dolichodinium conspicum), with tips blunt, capitate or aculeate distally and always free. Endophragm thin, usually smooth.
Pericoels: Cysts circumcavate, occasionally approaching cornucavate.
Tabulation: Delineated by sutural or penitabular processes on pericyst.
Archeopyle: Hypersoleiform. Periarcheopyle operculum generally attached along anterior margin and extending beyond anterior margin of endocyst in an apical direction. Endoarcheopyle with operculum attached anteriorly or free.
Furrows: Cingulum expressed by a single row of processes; sulcus delineated by processes.
Size: Large.
Affinities/Discussion:
Dolichodinium is the only known genus with a hypersoleiform archeopyle. Other wetzelielloidean genera with sutural and/or penitabular ornament are Castellodinium, Stichodinium, Vallodinium and Wilsonidium. Castellodinium, like Dolichodinium, has a perioperculum that is attached anteriorly, but the archeopyle is soleiform rather than hypersoleiform. Stichodinium has a latiepeliform archeopyle, Vallodinium has an equiepeliform archeopyle and Wilson-idium has a hyperepeliform archeopyle.
The holotype of Dolichodinium uncinatum has a pericyst length of 119 μm and a width of 128 μm.