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Dinogymnium longicorne
Dinogymnium longicornis (Vozzhennikova, 1967) Harland, 1973; emend. Lentin and Vozzhennikova, 1990
Originally Gymnodinium, subsequently (and now) Dinogymnium.
Taxonomic junior synonym: Gymnodinium (as Dinogymnium) curvatum, according to Lentin and Vozzhennikova (1990, p.18). Lentin and Williams (1973, p.49) also proposed this combination.
The combination Dinogymnium longicorne (Vozzhennikova, 1967) Harland, 1973, predates the same combination by Lentin and Williams, 1973.
Holotype: Vozzhennikova, 1967, pl.1, fig.8; Lentin and Vozzhennikova, 1990, pl.2, figs.1-2, text-fig.5a
Locus typicus: Yuzhno-Kopachevsk area, W Siberia, Russia
Stratum typicum: Senonian
Translation Vozzhennikova, 1967: Lees in Sarjeant (Ed.) 1971
Original description: Vozzhennilova, 1967, p. 67: Gymnodinium longicornis
Theca spindle-shaped, strongly elongated. Epitheca conical, rounded at the apical end and considerably larger than hypotheca. Hypotheca funnel-shaped; at a certain distance from the transverse furrow it tappers sharply or gradually to form a tubular antapical projection with is bluntly rounded at the end. Transverse furrow deep, slightly spiral. Longitudinal furrow slit-like and extending on to the epitheca. Theca smooth or pitted. The surface of the thecal envelope has ribbing which runs from the transverse furrow to the poles.
Dimensions: holotype - length 74.7 Ám, breadth 21.58 Ám, length of epitheca 21.58 Ám, length of hypotheca 46.48 Ám, width of transverse furrow 3.5 Ám, width of antapical outgrowth 8.35 Ám. The other examples have a length 62-64 Ám, a breadth 21-28 Ám, length of epitheca 18.4-27 Ám, length of hypotheca 43.7-46 Ám, width of transverse furrow 2.5-5 Ám, width of antapical end 4.6-8 Ám.
Supplemental description: Harland, 1973, p. 678
Proximate cyst, ovoidal to markedly elongate, made up of two closely adpressed wall layers. Test carries some longitudinal grooves and a fine micropunctation which is better developed in some specimens than others. The epitract conical to very elongate, drawn out into a long apical horn. The hypotract always hemispheroidal. A conspicuous cingulum always present, approximately 2 microns wide, in the form of a laevorotatory helicoid which is displaced by up to twice its width. A sulcus is present on the hypotract only. Faint sutural ridges are sometimes present, delimiting a possible tabulation; a possible reflected plate lp was observed in one specimen. Archeopyle apical, typical for the genus.
Dimensions. Range: Length 39.0(49.4)59.0 Ám; breadth 19.0(27.3)33.0 Ám, cingulum index 58 0 (65 75) 75 0. Eleven specimens studied.
Emended description: Lentin and Vozzhennikova, 1990, p. 18-19
Cyst shape distinctly elongate; epicyst long, funnel-shaped with tubular apex; hypocyst short, bluntly conical; autophragm microgranulose with distinct longitudinal ridges that extend nearly to the apex and antapex, interupted only by the paracingulum; archeopyle formed by two short arcuate sutures resulting in the loss of a very small apical paraplate at the apex of the tubular epicyst; paracingulum deep, dividing the cyst into two unequal portions, the epicyst being approximately 2/3 the total length and the hypocyst about 1/3; parasulcus narrow and deep, extending above and below the slightly off-set paracingulum.
Size: Holotype, length 75 Ám, width 22 Ám, width of paracingulum 3.5 Ám; range, length 62-75 Ám, width 21-28 Ám.
Affinities:
Vozzhennikova, 1967, p. 67: Gymnodinium longicornis
This species has some general similarity to G. curvatum from which it differs in the absence of any curvature to its hypotheca.
Originally Gymnodinium, subsequently (and now) Dinogymnium.
Taxonomic junior synonym: Gymnodinium (as Dinogymnium) curvatum, according to Lentin and Vozzhennikova (1990, p.18). Lentin and Williams (1973, p.49) also proposed this combination.
The combination Dinogymnium longicorne (Vozzhennikova, 1967) Harland, 1973, predates the same combination by Lentin and Williams, 1973.
Holotype: Vozzhennikova, 1967, pl.1, fig.8; Lentin and Vozzhennikova, 1990, pl.2, figs.1-2, text-fig.5a
Locus typicus: Yuzhno-Kopachevsk area, W Siberia, Russia
Stratum typicum: Senonian
Translation Vozzhennikova, 1967: Lees in Sarjeant (Ed.) 1971
Original description: Vozzhennilova, 1967, p. 67: Gymnodinium longicornis
Theca spindle-shaped, strongly elongated. Epitheca conical, rounded at the apical end and considerably larger than hypotheca. Hypotheca funnel-shaped; at a certain distance from the transverse furrow it tappers sharply or gradually to form a tubular antapical projection with is bluntly rounded at the end. Transverse furrow deep, slightly spiral. Longitudinal furrow slit-like and extending on to the epitheca. Theca smooth or pitted. The surface of the thecal envelope has ribbing which runs from the transverse furrow to the poles.
Dimensions: holotype - length 74.7 Ám, breadth 21.58 Ám, length of epitheca 21.58 Ám, length of hypotheca 46.48 Ám, width of transverse furrow 3.5 Ám, width of antapical outgrowth 8.35 Ám. The other examples have a length 62-64 Ám, a breadth 21-28 Ám, length of epitheca 18.4-27 Ám, length of hypotheca 43.7-46 Ám, width of transverse furrow 2.5-5 Ám, width of antapical end 4.6-8 Ám.
Supplemental description: Harland, 1973, p. 678
Proximate cyst, ovoidal to markedly elongate, made up of two closely adpressed wall layers. Test carries some longitudinal grooves and a fine micropunctation which is better developed in some specimens than others. The epitract conical to very elongate, drawn out into a long apical horn. The hypotract always hemispheroidal. A conspicuous cingulum always present, approximately 2 microns wide, in the form of a laevorotatory helicoid which is displaced by up to twice its width. A sulcus is present on the hypotract only. Faint sutural ridges are sometimes present, delimiting a possible tabulation; a possible reflected plate lp was observed in one specimen. Archeopyle apical, typical for the genus.
Dimensions. Range: Length 39.0(49.4)59.0 Ám; breadth 19.0(27.3)33.0 Ám, cingulum index 58 0 (65 75) 75 0. Eleven specimens studied.
Emended description: Lentin and Vozzhennikova, 1990, p. 18-19
Cyst shape distinctly elongate; epicyst long, funnel-shaped with tubular apex; hypocyst short, bluntly conical; autophragm microgranulose with distinct longitudinal ridges that extend nearly to the apex and antapex, interupted only by the paracingulum; archeopyle formed by two short arcuate sutures resulting in the loss of a very small apical paraplate at the apex of the tubular epicyst; paracingulum deep, dividing the cyst into two unequal portions, the epicyst being approximately 2/3 the total length and the hypocyst about 1/3; parasulcus narrow and deep, extending above and below the slightly off-set paracingulum.
Size: Holotype, length 75 Ám, width 22 Ám, width of paracingulum 3.5 Ám; range, length 62-75 Ám, width 21-28 Ám.
Affinities:
Vozzhennikova, 1967, p. 67: Gymnodinium longicornis
This species has some general similarity to G. curvatum from which it differs in the absence of any curvature to its hypotheca.