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Amphigymnium mitratum
Amphigymnium mitratum, (Vozzhennikova, 1967); Emendation: Lentin and Vozzhennikova, 1990
Originally Amphidinium, subsequently Dinogymnium, thirdly (and now) Amphigymnium.
At the time of the transfer, Lentin and Vozzhennikova, 1990, emended the description of this species.
Holotype: Vozzhennikova, 1967, pl.1, fig.2 and Lentin and Vozzhennikova, 1990, pl.1, figs.10-11; text-fig.12; Appendix A, fig.38.
Locus typicus: Western Siberia
Stratum typicum: Turonian-Senonian
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Original description as Amphidinium mitratum: [Vozzhennikova, 1967, p. 40]: (Translation: Lentin and Vozzhennikova, 1990):
Description:
Theca elongate oval. Epitheca small, conical, rounded at the apex, resembling a cap.
Hypotheca elongate, rounded at the free end.
Transverse furrow annulate, narrow and deep. Longitudinal furrow bounded by the hypovalve and expanding towards its end. Envelope delicate, with a smooth surface.
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Emended description:
Lentin and Vozzhennikova, 1990, p. 29-30:
Description:
Cysts elongate oval, epicyst small, conical, rounded at apex; hypocyst elongate with rounded antapex; autophragm thin, <1 µm, epicyst with delicate longitudinal ridges and smooth surface, hypocyst smooth, without ridges;
archeopyle formed by two short arcuate sutures about 3 µm in length;
paracingulum deep, dividing the cyst into two unequal portions, the epicyst being about 1/3 the length of the hypocyst;
parasulcus indicated by a shallow longitudinal depression, principally on the hypocyst immediately below the paracingulum.
Affinities:
The emendation of this species is necessary to include in the description details of the archeopyle and of the delicate longitudinal ridges on the epicyst. Neither of these features are discernible without oil immersion and Nomarski interference contrast. The holotype is located near a ridge on the surface of the coverslip which interferes with photography but in no way harms the specimen.
Originally Amphidinium, subsequently Dinogymnium, thirdly (and now) Amphigymnium.
At the time of the transfer, Lentin and Vozzhennikova, 1990, emended the description of this species.
Holotype: Vozzhennikova, 1967, pl.1, fig.2 and Lentin and Vozzhennikova, 1990, pl.1, figs.10-11; text-fig.12; Appendix A, fig.38.
Locus typicus: Western Siberia
Stratum typicum: Turonian-Senonian
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Original description as Amphidinium mitratum: [Vozzhennikova, 1967, p. 40]: (Translation: Lentin and Vozzhennikova, 1990):
Description:
Theca elongate oval. Epitheca small, conical, rounded at the apex, resembling a cap.
Hypotheca elongate, rounded at the free end.
Transverse furrow annulate, narrow and deep. Longitudinal furrow bounded by the hypovalve and expanding towards its end. Envelope delicate, with a smooth surface.
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Emended description:
Lentin and Vozzhennikova, 1990, p. 29-30:
Description:
Cysts elongate oval, epicyst small, conical, rounded at apex; hypocyst elongate with rounded antapex; autophragm thin, <1 µm, epicyst with delicate longitudinal ridges and smooth surface, hypocyst smooth, without ridges;
archeopyle formed by two short arcuate sutures about 3 µm in length;
paracingulum deep, dividing the cyst into two unequal portions, the epicyst being about 1/3 the length of the hypocyst;
parasulcus indicated by a shallow longitudinal depression, principally on the hypocyst immediately below the paracingulum.
Affinities:
The emendation of this species is necessary to include in the description details of the archeopyle and of the delicate longitudinal ridges on the epicyst. Neither of these features are discernible without oil immersion and Nomarski interference contrast. The holotype is located near a ridge on the surface of the coverslip which interferes with photography but in no way harms the specimen.