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Alisogymnium
From Williams et al., 2017:
[Alisogymnium, Lentin and Vozzhennikova, 1990, p. 24-25
Type species: originally Gymnodinium sphaerocephalum, Vozzhennikova, 1967 (pl.3, fig.1)] ; Alisogymnium sphaerocephalum, Lentin and Vozzhennikova, 1990
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Original description: [Lentin and Vozzhennikova, 1990]:
Description:
Fossil dinoflagellates which are elongate elipsoidal; the epicyst usually longer than the hypocyst and somewhat tubular; hypocyst is broadly rounded, bowl-shaped.
The autophragm may be smooth, granulose or microporate with longitudinal ridges on the epicyst which extend to or nearly to the apex, hypocyst may be with or without longitudinal ridges, they may be restricted to the area immediately posterior to the paracingulum or extend not more than about 1/2 the distance to the antapex.
The archeopyle is formed by two arcuate sutures of equal length which result in the loss of a single paraplate on the apex on the cyst.
The paracingulum is deep, dividing the cyst into two unequal portions, the hypocyst being about 1/3 the length of the epicyst.
The parasulcus is indicated by a shallow longitudinal depression, principally on the hypocyst, immediately below the paracingulum.
Affinities:
Alisogymnium is separated from Dinogymnium on the basis of the bowl shape of the hypocyst which generally is without or has very reduced longitudinal ridges. This characteristic is found in eight of the species formerly asgigned to Dinogymnium.
Alisogymnium differs from Amphigymnium which is oval in outline and has a thin, non-costate phragma and from Yolkinigymnium which is extremely long and narrow in outline.
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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.
Alisogymnium Lentin and Vozzhennikova, 1990, has an episome that is tapered and generally longer than the rounded hyposome. Alisogymnium differs from Amphigymnium , which is oval in outline and has a thin, non-costate phragma and from Yolkinogymnium which is extremely long.
[Alisogymnium, Lentin and Vozzhennikova, 1990, p. 24-25
Type species: originally Gymnodinium sphaerocephalum, Vozzhennikova, 1967 (pl.3, fig.1)] ; Alisogymnium sphaerocephalum, Lentin and Vozzhennikova, 1990
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Lentin and Vozzhennikova, 1990]:
Description:
Fossil dinoflagellates which are elongate elipsoidal; the epicyst usually longer than the hypocyst and somewhat tubular; hypocyst is broadly rounded, bowl-shaped.
The autophragm may be smooth, granulose or microporate with longitudinal ridges on the epicyst which extend to or nearly to the apex, hypocyst may be with or without longitudinal ridges, they may be restricted to the area immediately posterior to the paracingulum or extend not more than about 1/2 the distance to the antapex.
The archeopyle is formed by two arcuate sutures of equal length which result in the loss of a single paraplate on the apex on the cyst.
The paracingulum is deep, dividing the cyst into two unequal portions, the hypocyst being about 1/3 the length of the epicyst.
The parasulcus is indicated by a shallow longitudinal depression, principally on the hypocyst, immediately below the paracingulum.
Affinities:
Alisogymnium is separated from Dinogymnium on the basis of the bowl shape of the hypocyst which generally is without or has very reduced longitudinal ridges. This characteristic is found in eight of the species formerly asgigned to Dinogymnium.
Alisogymnium differs from Amphigymnium which is oval in outline and has a thin, non-costate phragma and from Yolkinigymnium which is extremely long and narrow in outline.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Alisogymnium Lentin and Vozzhennikova, 1990, has an episome that is tapered and generally longer than the rounded hyposome. Alisogymnium differs from Amphigymnium , which is oval in outline and has a thin, non-costate phragma and from Yolkinogymnium which is extremely long.