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Arvalidinium
From Williams et al., 2017:
[Arvalidinium, Lentin and Vozzhennikova, 1990, p.33-34
Type species: originally as Chatangiella arvensis, Marshall, 1988 (figs.17M–R)] ; Arvalidinium arvense, Lentin and Vozzhennikova, 1990
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Original description: [Lentin and Vozzhennikova, 1990]:
Description:
Fossil dinoflagellate cysts with one apical and two antapical horns, the latter may be equal in length, undeveloped or the right horn shorter than the left; lateral margins of epicyst adjacent to archeopyle expanded by weak to distinct rounded shoulders; endocyst round to roundly rectangular, commonly wider than long; bicavate to rarely circumcavate. Periphragm smooth to granulose or with low intratabular elements of low relief (grani, coni, baculae and spines); endophragm smooth to granulose, occasionally thickened and appearing fibrous or sponge like within the pericoels.
Paratabulation indicated by parasutural ridges or projections of low relief, the archeopyle and paracingulum; peridinioid, formula 4`, 3a, 7``, Xc, 5```, 2````.
The periarcheopyle thetaform to omegaform with operculum attached along the 4`` - 2a parasuture or, rarely, free; endoarcheopyle is 3I or undeveloped.
The paracingulum is expressed by two parallel discontinuous ridges which are pentapartite. Parasulcus indicated by a shallow depression on the midventral surface.
Affinities:
Arvalidinium differs from Chatangiella in having a generally more peridinioid outline with reduced shoulders and distinct parasutural features which outline the paratabulation.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Arvalidinium Lentin and Vozzhennikova, 1990, has two equal or unequal antapical horns and weak shoulders. Paratabulation peridinioid, indicated by parasutural ridges or projections of low relief. Periarcheopyle thetaform to omegaform with attached or rarely free operculum. Endoarcheopyle 3I or undeveloped. Paracingulum expressed by two parallel discontinuous ridges which are pentapartite.
[Arvalidinium, Lentin and Vozzhennikova, 1990, p.33-34
Type species: originally as Chatangiella arvensis, Marshall, 1988 (figs.17M–R)] ; Arvalidinium arvense, Lentin and Vozzhennikova, 1990
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Lentin and Vozzhennikova, 1990]:
Description:
Fossil dinoflagellate cysts with one apical and two antapical horns, the latter may be equal in length, undeveloped or the right horn shorter than the left; lateral margins of epicyst adjacent to archeopyle expanded by weak to distinct rounded shoulders; endocyst round to roundly rectangular, commonly wider than long; bicavate to rarely circumcavate. Periphragm smooth to granulose or with low intratabular elements of low relief (grani, coni, baculae and spines); endophragm smooth to granulose, occasionally thickened and appearing fibrous or sponge like within the pericoels.
Paratabulation indicated by parasutural ridges or projections of low relief, the archeopyle and paracingulum; peridinioid, formula 4`, 3a, 7``, Xc, 5```, 2````.
The periarcheopyle thetaform to omegaform with operculum attached along the 4`` - 2a parasuture or, rarely, free; endoarcheopyle is 3I or undeveloped.
The paracingulum is expressed by two parallel discontinuous ridges which are pentapartite. Parasulcus indicated by a shallow depression on the midventral surface.
Affinities:
Arvalidinium differs from Chatangiella in having a generally more peridinioid outline with reduced shoulders and distinct parasutural features which outline the paratabulation.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Arvalidinium Lentin and Vozzhennikova, 1990, has two equal or unequal antapical horns and weak shoulders. Paratabulation peridinioid, indicated by parasutural ridges or projections of low relief. Periarcheopyle thetaform to omegaform with attached or rarely free operculum. Endoarcheopyle 3I or undeveloped. Paracingulum expressed by two parallel discontinuous ridges which are pentapartite.