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Hystrichodinium
From Williams et al., 2017:
[Hystrichodinium, Deflandre, 1935, p. 229-230; Emendations: Sarjeant, 1966b, p. 140; Clarke and Verdier, 1967, p. 37–38; Pestchevitskaya, 2009, p. 111.
Tax. jun. syn.: Cauca, according to Below (1981b, p.120–121) — however, Lentin and Williams (1985, p.48) retained Cauca.
Type species: Hystrichodinium pulchrum, Deflandre, 1935 (pl.5, fig.1; text-figs.9–11)]
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Original description: [Deflandre, 1935]: (Translation: Stover and Evitt, 1978, p. 161):
Description:
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.
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Emended descriptions:
Sarjeant, 1966:
Diagnosis:
Proximo-chorate dinoflagellat cysts, spheroidal, ovoidal or polygonal in shape. tabulation in general accord with Gonyaulax pattern, but not determined in detail.
Long, hollow spines, rounded in cross-section and fairly stiff, arising from positions of plate boundaries: plate boundaries otherwise marked by low crests or not at all.
Cingulum strongly or weakly helicoid, well-marked; sulcus poorly marked. Length of spines variable, but typically exceeding 1/2 of shell width. Shell surface smooth, granular, punctate, nodose or areolate.
A precingular archaeopyle formed, presumably by loss of plate 3``.
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Clarke and Verdier, 1967:
Description:
Dinoflagellate cysts with a helicoid girdle, tabulation, a precingular archaeopyle and the possession of numerous hollow processes.
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Modified description:
Stover and Evitt, 1978, p. 161:
Synopsis:
Cysts skolochorate; body subspherical to polyhedral, bearing numerous parasutural spines; paratabulation indicated mainly by archeopyle, clearly to vaguely by alignment of spines; archeopyle precingular, Type P.
Description:
Shape: Body subspherical to polyhedral.
Wall relationships: Autophragm only.
Wall features: Parasutural spines hollow, and taper off evenly to simple or branched tips; bases of adjacent spines may be joined by low parasutural ridges. Areas between rows of spines typically bear circular markings, which may be pores or sharply defined tuberculae.
Paratabulation: Indicated by archeopyle and, clearly to vaguely, by alignment of spines, rarely by distinct parasutural ridges; gonyaulacacean, formula rarely determinable: 4`, 6``, 6c, 6```, 1p, 1````.
Archeopyle: Precingular, Type P (3`` only), which may not be readily apparent; operculum free.
Paracingulum: Clearly indicated by low parasutural ridges on some forms; indicated faintly or not at all on others.
Parasulcus: Generally not indicated.
Size: Intermediate to large.
Affinities:
Hystrichodinium differs from Xiphophoridium in having a precingular rather than an apical archeopyle. Although the type of archeopyle on Raphidodinium is unknown, the genus resembles Hystrichodinium in having long simple gonal processes.
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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.
Hystrichodinium Deflandre, 1935, emend. Sarjeant, 1966b, emend. Clarke and Verdier, 1967, has gonyaulacoid tabulation delineated by sutural crests, gonal and sutural processes and a P(3") archeopyle. The processes are never of the Spiniferites type although they can be furcate.
[Hystrichodinium, Deflandre, 1935, p. 229-230; Emendations: Sarjeant, 1966b, p. 140; Clarke and Verdier, 1967, p. 37–38; Pestchevitskaya, 2009, p. 111.
Tax. jun. syn.: Cauca, according to Below (1981b, p.120–121) — however, Lentin and Williams (1985, p.48) retained Cauca.
Type species: Hystrichodinium pulchrum, Deflandre, 1935 (pl.5, fig.1; text-figs.9–11)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Deflandre, 1935]: (Translation: Stover and Evitt, 1978, p. 161):
Description:
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.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Sarjeant, 1966:
Diagnosis:
Proximo-chorate dinoflagellat cysts, spheroidal, ovoidal or polygonal in shape. tabulation in general accord with Gonyaulax pattern, but not determined in detail.
Long, hollow spines, rounded in cross-section and fairly stiff, arising from positions of plate boundaries: plate boundaries otherwise marked by low crests or not at all.
Cingulum strongly or weakly helicoid, well-marked; sulcus poorly marked. Length of spines variable, but typically exceeding 1/2 of shell width. Shell surface smooth, granular, punctate, nodose or areolate.
A precingular archaeopyle formed, presumably by loss of plate 3``.
-----------------------------------------
Clarke and Verdier, 1967:
Description:
Dinoflagellate cysts with a helicoid girdle, tabulation, a precingular archaeopyle and the possession of numerous hollow processes.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt, 1978, p. 161:
Synopsis:
Cysts skolochorate; body subspherical to polyhedral, bearing numerous parasutural spines; paratabulation indicated mainly by archeopyle, clearly to vaguely by alignment of spines; archeopyle precingular, Type P.
Description:
Shape: Body subspherical to polyhedral.
Wall relationships: Autophragm only.
Wall features: Parasutural spines hollow, and taper off evenly to simple or branched tips; bases of adjacent spines may be joined by low parasutural ridges. Areas between rows of spines typically bear circular markings, which may be pores or sharply defined tuberculae.
Paratabulation: Indicated by archeopyle and, clearly to vaguely, by alignment of spines, rarely by distinct parasutural ridges; gonyaulacacean, formula rarely determinable: 4`, 6``, 6c, 6```, 1p, 1````.
Archeopyle: Precingular, Type P (3`` only), which may not be readily apparent; operculum free.
Paracingulum: Clearly indicated by low parasutural ridges on some forms; indicated faintly or not at all on others.
Parasulcus: Generally not indicated.
Size: Intermediate to large.
Affinities:
Hystrichodinium differs from Xiphophoridium in having a precingular rather than an apical archeopyle. Although the type of archeopyle on Raphidodinium is unknown, the genus resembles Hystrichodinium in having long simple gonal processes.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Hystrichodinium Deflandre, 1935, emend. Sarjeant, 1966b, emend. Clarke and Verdier, 1967, has gonyaulacoid tabulation delineated by sutural crests, gonal and sutural processes and a P(3") archeopyle. The processes are never of the Spiniferites type although they can be furcate.