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Hystrichodinium pulchrum ssp. pulchrum
Hystrichodinium pulchrum ssp. pulchrum
Autonym.
Holotype: Deflande, 1936, pl.8, fig.3-4
Paratypes: Deflandre, 1936
Locus typicus: Silex (galet), Le MÚe, Seine-et-Marne, France
Stratum typicum: Senonian
Translation Deflandre, 1935: Stover and Evitt, 1978, p. 161
Translation Deflandre, 1936: LPP
Original description: Deflandre, 1935, p. 229-230
Its general form is that of a Peridinium with epitheca and hypotheca of similar size, and with helicoid transverse furrow. The entire organism is bristling with long hollow horns, distributed on the whole surface of the theca, and as far as the lips of the furrows, principally the lower lip. The surface of the membrane shows a very distinct ornamentation in some specimens, recalling that of certain Histioneis, but I have not yet been able to see sutures indicating the presence of plates. The absence of these would remove our organism from the Peridiniidae. Its helicoidal furrow and the respective proportions of the epitheca and hypotheca do not permit relating it to the Cladopyxidae, the only dinoflagellates today possessing such horns, although in less abundance (cf., for example, Acanthodinium spinosum Kof.). Hystrichodinium represents, in fact, a type completely different from all known dinoflagellates, on the position and systematic affinities of which I will not dwell any longer. I will add to my short description that the horns, curved and flexible in my figs. 9, 10, are much more often radial and straight, even more rigid than in the microphotograph of Plate V.
Improved description: Deflandre, 1936, p. 183
(annotated) The transverse furrow, helicoid an laevorotatory, divides the theca in two clearly equal parts: the epitheca, which is slightly conical, with well-rounded sides, and the more or less hemispherical hypotheca. I did not observe signs of sutures, in spite of certain appearances due to folding of the membrane, and the two parts thus seem to consist of one piece.
The transverse furrow, in certain well-preserved specimens, shows delicate transverse trabeculae, as seen in many dinoflagellates. These trabeculae unite two rows of punctations, which are easily observed on most of the specimens.
The longitudunal furrow, represented by a simple recess in the epitheca, extends about halfway onto the hypotheca, but, given the frequent folding, it may even be longer.
The entire surface of the theca is set with long, pointed, hollow horns, widening at the base to fuse with the membrane without a trace of attachment. These horns appear to be distributed quite irregularly, although they are clearly equidistant. They radiate all around the theca, the margins of the furrows included, and they must be rigid in the living condition. However, quite some specimens present them diversely recurved, which testifies to a certain flexibility, because they are rarely broken. Their length generally exceeds half the theca diameter and often reaches that diameter.
The membrane itself is covered with strong punctuations. In certain specimens, these punctuations occupy the centre of depressed, rounded polygonal areolae. The punctuations are regularly distributed along lines parallel to the transverse furrow, and - less regularly - along meridian lines.
Dimensions: length excluding horns 45/55 Ám, length including horns 110-125 Ám, width excluding horns 42-48 Ám.
Autonym.
Holotype: Deflande, 1936, pl.8, fig.3-4
Paratypes: Deflandre, 1936
Locus typicus: Silex (galet), Le MÚe, Seine-et-Marne, France
Stratum typicum: Senonian
Translation Deflandre, 1935: Stover and Evitt, 1978, p. 161
Translation Deflandre, 1936: LPP
Original description: Deflandre, 1935, p. 229-230
Its general form is that of a Peridinium with epitheca and hypotheca of similar size, and with helicoid transverse furrow. The entire organism is bristling with long hollow horns, distributed on the whole surface of the theca, and as far as the lips of the furrows, principally the lower lip. The surface of the membrane shows a very distinct ornamentation in some specimens, recalling that of certain Histioneis, but I have not yet been able to see sutures indicating the presence of plates. The absence of these would remove our organism from the Peridiniidae. Its helicoidal furrow and the respective proportions of the epitheca and hypotheca do not permit relating it to the Cladopyxidae, the only dinoflagellates today possessing such horns, although in less abundance (cf., for example, Acanthodinium spinosum Kof.). Hystrichodinium represents, in fact, a type completely different from all known dinoflagellates, on the position and systematic affinities of which I will not dwell any longer. I will add to my short description that the horns, curved and flexible in my figs. 9, 10, are much more often radial and straight, even more rigid than in the microphotograph of Plate V.
Improved description: Deflandre, 1936, p. 183
(annotated) The transverse furrow, helicoid an laevorotatory, divides the theca in two clearly equal parts: the epitheca, which is slightly conical, with well-rounded sides, and the more or less hemispherical hypotheca. I did not observe signs of sutures, in spite of certain appearances due to folding of the membrane, and the two parts thus seem to consist of one piece.
The transverse furrow, in certain well-preserved specimens, shows delicate transverse trabeculae, as seen in many dinoflagellates. These trabeculae unite two rows of punctations, which are easily observed on most of the specimens.
The longitudunal furrow, represented by a simple recess in the epitheca, extends about halfway onto the hypotheca, but, given the frequent folding, it may even be longer.
The entire surface of the theca is set with long, pointed, hollow horns, widening at the base to fuse with the membrane without a trace of attachment. These horns appear to be distributed quite irregularly, although they are clearly equidistant. They radiate all around the theca, the margins of the furrows included, and they must be rigid in the living condition. However, quite some specimens present them diversely recurved, which testifies to a certain flexibility, because they are rarely broken. Their length generally exceeds half the theca diameter and often reaches that diameter.
The membrane itself is covered with strong punctuations. In certain specimens, these punctuations occupy the centre of depressed, rounded polygonal areolae. The punctuations are regularly distributed along lines parallel to the transverse furrow, and - less regularly - along meridian lines.
Dimensions: length excluding horns 45/55 Ám, length including horns 110-125 Ám, width excluding horns 42-48 Ám.