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Epelidinium
From Williams et al., 2017:
[Epelidinium, Williams et al., 2015, p. 305.
Type species: as Wilsonidium pechoricum, Lakovleva and Heilmann-Clausen, 2007 (fig.2, nos.4–5; fig.3, no.1.)]
Stratigraphic occurrence: Early to Late Eocene (Ypresian to Priabonian). Some uncertainty exists as to the youngest occurrence of this genus.
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Original description [Williams et al., 2015]:
Diagnosis:
Wetzelielloidean cysts with an equiepeliform archeopyle and pericyst unornamented or with features of low relief.
Description:
Shape: Dorso-ventral outline of pericyst rhomboidal, with variable development of apical horn. Right antapical horn reduced or denoted by a bulge. Dorso-ventral outline of endocyst rounded quadrate to ovoidal.
Wall structure: Periphragm thin, smooth or with features of low relief. Endophragm of variable thickness, typically unornamented.
Pericoels: Cavation is variable, circumcavate to cornucavate; may be epicavate.
Tabulation: Suggested by features of low relief on periphragm.
Archeopyle: Equiepeliform. Periarcheopyle operculum free. Endoarcheopyle of same size or slightly smaller than periarcheopyle, operculum free. Furrows: Cingulum incompletely delineated, typically suggested by folding or thickening of periphragm.
Size: Intermediate to large.
Affinities:
Other genera having an equiepeliform archeopyle are Apectodinium, Axiodinium, Charlesdowniea, Sophismatia and Vallodinium. Apectodinium and Axiodinium have processes that are distally free, Charlesdownia has an ectophragm, Sophismatia has trabeculate processes, and Vallodinium has sutural to penitabular ornamentation on the pericyst. Genera also having a pericyst that is unornamented or has only features of low relief include Petalodinium, Rhadinodinium and Rhombodinium. Petalodinium has a latiepeliform archeopyle, Rhadinodinium has a hyperepeliform archeopyle and Rhombodinium has a soleiform archeopyle. The holotype of Epelidinium pechoricum has a pericyst 101 µm long and 97 µm wide. The respective dimensions for the holotype of Epelidinium? translucidum are 126 µm and 135 µm.
[Epelidinium, Williams et al., 2015, p. 305.
Type species: as Wilsonidium pechoricum, Lakovleva and Heilmann-Clausen, 2007 (fig.2, nos.4–5; fig.3, no.1.)]
Stratigraphic occurrence: Early to Late Eocene (Ypresian to Priabonian). Some uncertainty exists as to the youngest occurrence of this genus.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description [Williams et al., 2015]:
Diagnosis:
Wetzelielloidean cysts with an equiepeliform archeopyle and pericyst unornamented or with features of low relief.
Description:
Shape: Dorso-ventral outline of pericyst rhomboidal, with variable development of apical horn. Right antapical horn reduced or denoted by a bulge. Dorso-ventral outline of endocyst rounded quadrate to ovoidal.
Wall structure: Periphragm thin, smooth or with features of low relief. Endophragm of variable thickness, typically unornamented.
Pericoels: Cavation is variable, circumcavate to cornucavate; may be epicavate.
Tabulation: Suggested by features of low relief on periphragm.
Archeopyle: Equiepeliform. Periarcheopyle operculum free. Endoarcheopyle of same size or slightly smaller than periarcheopyle, operculum free. Furrows: Cingulum incompletely delineated, typically suggested by folding or thickening of periphragm.
Size: Intermediate to large.
Affinities:
Other genera having an equiepeliform archeopyle are Apectodinium, Axiodinium, Charlesdowniea, Sophismatia and Vallodinium. Apectodinium and Axiodinium have processes that are distally free, Charlesdownia has an ectophragm, Sophismatia has trabeculate processes, and Vallodinium has sutural to penitabular ornamentation on the pericyst. Genera also having a pericyst that is unornamented or has only features of low relief include Petalodinium, Rhadinodinium and Rhombodinium. Petalodinium has a latiepeliform archeopyle, Rhadinodinium has a hyperepeliform archeopyle and Rhombodinium has a soleiform archeopyle. The holotype of Epelidinium pechoricum has a pericyst 101 µm long and 97 µm wide. The respective dimensions for the holotype of Epelidinium? translucidum are 126 µm and 135 µm.