Back
Nannoceratopsis pellucida
Nannoceratopsis pellucida Deflandre, 1938; emend. Evitt, 1961
Holotype: Deflandre, 1938, pl.8, fig.10
Locus typicus: Villers-sur-mer, France
Stratum typicum: Oxfordian
Translation Deflandre, 1938: LPP
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nannoceratopsis pellucida Deflandre, 1939a, emend. Evitt, 1961b. According to Evitt (1961b), Nannoceratopsis pellucida has a subtriangular outline and two antapical horns about equal, long and large, separated by a deep concavity. Variability slight; specimens having one horn greatly reduced are unknown. Sagittal band narrow; limiting ridges commonly narrow and faint so that longitudinal furrow is not conspicuously differentiated from rest of band. Typical size about 88 by 45 µm in lateral view.
--------------------------------------------------
Original description: Deflandre 1938, p. 183-139
(annotated) In frontal view, the general form would be that of a curvilineal isosceles triangle, of which only the base would be strongly concave. the top of the triangle, truncate on some, apparently incomplete specimens, is occupied by the apex which has been described (in the description of the genus). The specimen depicted in pl.8, fig.10 is seen in dorsoventral view, and the indication, as a perforate line, of the transverse furrow, indicates that it is observed in transmitted light.
The two horns which lengthen the convex sides vary in length per specimen: however, they appear to be identical. The terminate in a more or less blunt tip. The membrane is finely, but distinctly areolate. It is very glassy and colourless.
It seems that some folds or striations are reproduced on several specimens, giving the impression of a tabulation; but this requires verification.
The holotype is 88 µm long and 45 µm wide. It may attain a length of 90-100 µm. The apical horns are about 30-35 µm.
Emended description: Evitt, 1961, p. 312
Outline subtriangular; two antapical horns about equal, long and large, separated by deep concavity. Variability slight; specimens having one horn greatly reduced are unknown. Sagittal band narrow; limiting ridges commonly narrow and faint so that longitudinal furrow is not conspicuously differentiated from rest of band. Typical size about 88 by 45 Ám in lateral view.
Remarks on specific characters Evitt, 1961, p.314:
Careful study of the available specimens of N. pellucida from Utah confirms that the chief morphological features described in N. deflandrei also occur in this species:
1) A narrow sagittal band is present, separated from the two large lateral surfaces by narrow ridges.
2) A longitudinal furrow can be distinguished in the apical portion of this band on the ventral side.
3) A girdle (the oblique furrow observed by Deflandre) enters the longitudinal furrow obliquely near its apical end. The girdle continues around the dorsal surface and ends on the left side.
4) A narrow ridge joins the minute epitheca ventrally with the lefthand edge of the longitudinal furrow.
5) A somewhat undulated flap begins on the ridge mentioned above, then expands along the apical edge of the girdle on the right side. A narrow thickening occurs on the apical edge of the girdle on the left side.
It is not surprising that Deflandre failed to call attention to some features noted above, nor that he interpreted others somewhat differently than I do. They are, for the most part, much more difficult to discern in N. pellucida than in N. deflandrei. This seems to result primarily from the more delicate construction of N. pellucida. Its wall is thinner and the ridges at the junctions between the lateral surfaces and the sagittal band are less prominent.
However, having the morphology of N. deflandrei in mind, all the essential structures can be recognized in the type species. The differences between the two species, including their variability, are discussed under N. deflandrei.
Holotype: Deflandre, 1938, pl.8, fig.10
Locus typicus: Villers-sur-mer, France
Stratum typicum: Oxfordian
Translation Deflandre, 1938: LPP
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Nannoceratopsis pellucida Deflandre, 1939a, emend. Evitt, 1961b. According to Evitt (1961b), Nannoceratopsis pellucida has a subtriangular outline and two antapical horns about equal, long and large, separated by a deep concavity. Variability slight; specimens having one horn greatly reduced are unknown. Sagittal band narrow; limiting ridges commonly narrow and faint so that longitudinal furrow is not conspicuously differentiated from rest of band. Typical size about 88 by 45 µm in lateral view.
--------------------------------------------------
Original description: Deflandre 1938, p. 183-139
(annotated) In frontal view, the general form would be that of a curvilineal isosceles triangle, of which only the base would be strongly concave. the top of the triangle, truncate on some, apparently incomplete specimens, is occupied by the apex which has been described (in the description of the genus). The specimen depicted in pl.8, fig.10 is seen in dorsoventral view, and the indication, as a perforate line, of the transverse furrow, indicates that it is observed in transmitted light.
The two horns which lengthen the convex sides vary in length per specimen: however, they appear to be identical. The terminate in a more or less blunt tip. The membrane is finely, but distinctly areolate. It is very glassy and colourless.
It seems that some folds or striations are reproduced on several specimens, giving the impression of a tabulation; but this requires verification.
The holotype is 88 µm long and 45 µm wide. It may attain a length of 90-100 µm. The apical horns are about 30-35 µm.
Emended description: Evitt, 1961, p. 312
Outline subtriangular; two antapical horns about equal, long and large, separated by deep concavity. Variability slight; specimens having one horn greatly reduced are unknown. Sagittal band narrow; limiting ridges commonly narrow and faint so that longitudinal furrow is not conspicuously differentiated from rest of band. Typical size about 88 by 45 Ám in lateral view.
Remarks on specific characters Evitt, 1961, p.314:
Careful study of the available specimens of N. pellucida from Utah confirms that the chief morphological features described in N. deflandrei also occur in this species:
1) A narrow sagittal band is present, separated from the two large lateral surfaces by narrow ridges.
2) A longitudinal furrow can be distinguished in the apical portion of this band on the ventral side.
3) A girdle (the oblique furrow observed by Deflandre) enters the longitudinal furrow obliquely near its apical end. The girdle continues around the dorsal surface and ends on the left side.
4) A narrow ridge joins the minute epitheca ventrally with the lefthand edge of the longitudinal furrow.
5) A somewhat undulated flap begins on the ridge mentioned above, then expands along the apical edge of the girdle on the right side. A narrow thickening occurs on the apical edge of the girdle on the left side.
It is not surprising that Deflandre failed to call attention to some features noted above, nor that he interpreted others somewhat differently than I do. They are, for the most part, much more difficult to discern in N. pellucida than in N. deflandrei. This seems to result primarily from the more delicate construction of N. pellucida. Its wall is thinner and the ridges at the junctions between the lateral surfaces and the sagittal band are less prominent.
However, having the morphology of N. deflandrei in mind, all the essential structures can be recognized in the type species. The differences between the two species, including their variability, are discussed under N. deflandrei.