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Gonyaulacysta jurassica
Gonyaulacysta jurassica (Deflandre, 1939a, p.168, pl.6, figs.2–5; text-figs.1–2) Norris and Sarjeant, 1965, p.65. Emendation: Sarjeant, 1982b, p.28–30, as Gonyaulacysta jurassica.
Originally Gonyaulax, subsequently (and now) Gonyaulacysta.
Taxonomic junior synonym: Psaligonyaulax (as and now Gonyaulacysta) dualis, according to Sarjeant (1982b, p.29) — however, Jan du Chêne et al. (1986a, p.131) retained Gonyaulacysta dualis. Górka (1965, p.298) also proposed this combination.
Holotype: Deflandre, 1938, pl.6, fig.2-3; Sarjeant, 1982, pl.6, fig.1-2; Jan du Chene et al.,1986, pl.37, fig.1-3
Paratypes: Deflandre, 1938; Sarjeant, 1982; Jan du Chene et al., 1986, pl.37, fig.4-6
Locus typicus: Villers-sur-Mer, Calvados, France
Stratum typicum: Oxfordian
Translation Deflandre, 1938: LPP
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Gonyaulacysta jurassica (Deflandre, 1939a) Norris and Sarjeant, 1965, emend. Sarjeant, 1982b. According to Sarjeant (1982b), Gonyaulacysta jurassica has a tabulation of 2pa, 4', 2a, 6", 6c, 6"’, 1p, 1pv, 1"”. The epicyst is always considerably longer than the hypocyst and there is an epicystal pericoel below the apical horn. Sometimes there is an opisthopyle. G.jurassica is also characterised by the parasutural septa with serrated crests. The 6" plate is elongate. Size:
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Original description: Deflandre 1938, p. 168: Gonyaulax jurassica
(annotated) The cell is elongate, generally polygonal in frontal view and the helocoidal transverse furrow divides it into two unequal parts. The epitheca, always larger than the hypotheca, is more or less conical and terminates in a clearly cylindrical, hollow horn. The sides of the epitheca are straight ot slightly concave or convex. The same holds for the hypotheca, the sides of which, however, are more rarely convex. The hypohteca is trapezoidal, sometimes with a slightly rounded pole.
The plate-sutures bear thin, but relatively high ribs with finely denticulate rims. The transverse furrow as well (but not always) bears fine denticulations on its rim. On the hypotheca, the plate-sutures lenghten gonally into short denticulate horns, the development of which varies per specimen.
The epitheca has six preequatorial plates, the sixth of which is clearly more reduced than the others. Three apical plates join to form the tubular apical horn; one, adjacent to the sixth preequatorial plate, is situated in line with the longitudinal furrow, the others are adjacent to the preequatorials 1-2-3 and 3-4-5 respectively, their sutural line clearly running into the area of the upper part of of the third preequatorial. In all specimens, the third preequatorial is missing.
The hypotheca has six postequatorial plates, one polygonal antapical plate and an inermediate. The first postequatorial plate (1''') is very reduced and remains easily unnoticed. The intermediate plate (1p) is adjacent to the second and third preequatorial (sic, should be: postequatorial), to the antapical plate and the longitudinal furrow. The sutural ribs between plates 2-3, 3-4, 4-5 and 5-6 lengthen, as described earlier, into four denticulate horns, sometimes very reduced, sometimes very well developed. Some specimens of G. jurassica, until now rarely, have a fifth horn, situated on the suture 2-3, at the corner of plates 2''' and 1p.
The general form of G. jurassica mainly varies from bulging specimens with convex sides to specimens with concave sides.
The membrane on most specimens appears to be smooth or at the most finely punctate.
Dimensions: holotype 79x55 Ám. Range: length 60-100 Ám.
Supplemental description: Pocock, 1972, p.88
Vesicle longer than it is broad; epitheca hemispherical; terminated by a prominent, blunt-tipped horn made up of three elongate thecal plates (1', 2', and 3'); equatorial furrow well developed, helicoidal; hypotheca hemispherical; longitudinal furrow widest towards the antapex, narrowing to a point on the epitheca were it abuts against the antapical end of plate 1'; tabulation 3', 6", 6''', 1''''; sutures well defined, forming relatively wide ridges, usually finely serrate at their crests; test thin-walled; smooth; colourlless to pale yellow; length of test (inclusive of apical horn and crest to plate 1'''') 103.0--105 Ám (ridges shortest at equator; longest on plate 1'''').
Emended diagnosis: Sarjeant, 1982, p. 30
Cyst irregularly hexagonal to rounded-hexagonal in ambitus, prolonged apically into a mamelon or horn of highly variable length. Epitract in the form of a cone truncated at one-half to two-thirds height; hypotract smaller, in the form of an inverted cone truncated at one-third to one-half its height. Flanks of epitract and hypotract convex, planar or slightly concave. Epipericoel consistently developed, sometimes entirely confined to the horn, more often also occupying the apical region of the cyst to a varying degree; a hypopericoel may be present, developed only marginally, or completely lacking. Paraplates well marked by low to moderately high crests of variable form-irregularly to regularly serrate, denticulate, echinate or acanthate; crenellate, hystricate or phractate; or exhibiting complex intermediates between these types. Gonal spines present or absent, sometimes longest at the antapex and sustaining caudiculae. Paratabulation 2pa, 4', 2a, 6'', 6c, 6''', 1p, 1pv, 1''''. Paraplate 4' is elongate, less long than 1', with only a small contact with an elongate triangular 6''. The crests separating 4' from 6'' intersects the right lateral crest of 1' in a position markedly anterior to the junction of the latter paraplate with the sulcus. Archaeopyle single-plate precingular, formed by loss of paraplate 3'''; an opisthopyle may be developed in paraplate 1pv of delphicavate or bicavate specimens.
Affinities:
Pocock, 1972, p. 88: The Canadian specimens are larger, on average, than European ones, but there can be little doubt as to their identity. The smoothly ovoid test with prominent apical horn, wide sutural ridges and comparatively simple plating are characteristic of this species.
Originally Gonyaulax, subsequently (and now) Gonyaulacysta.
Taxonomic junior synonym: Psaligonyaulax (as and now Gonyaulacysta) dualis, according to Sarjeant (1982b, p.29) — however, Jan du Chêne et al. (1986a, p.131) retained Gonyaulacysta dualis. Górka (1965, p.298) also proposed this combination.
Holotype: Deflandre, 1938, pl.6, fig.2-3; Sarjeant, 1982, pl.6, fig.1-2; Jan du Chene et al.,1986, pl.37, fig.1-3
Paratypes: Deflandre, 1938; Sarjeant, 1982; Jan du Chene et al., 1986, pl.37, fig.4-6
Locus typicus: Villers-sur-Mer, Calvados, 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.
Gonyaulacysta jurassica (Deflandre, 1939a) Norris and Sarjeant, 1965, emend. Sarjeant, 1982b. According to Sarjeant (1982b), Gonyaulacysta jurassica has a tabulation of 2pa, 4', 2a, 6", 6c, 6"’, 1p, 1pv, 1"”. The epicyst is always considerably longer than the hypocyst and there is an epicystal pericoel below the apical horn. Sometimes there is an opisthopyle. G.jurassica is also characterised by the parasutural septa with serrated crests. The 6" plate is elongate. Size:
--------------------------------------------------
Original description: Deflandre 1938, p. 168: Gonyaulax jurassica
(annotated) The cell is elongate, generally polygonal in frontal view and the helocoidal transverse furrow divides it into two unequal parts. The epitheca, always larger than the hypotheca, is more or less conical and terminates in a clearly cylindrical, hollow horn. The sides of the epitheca are straight ot slightly concave or convex. The same holds for the hypotheca, the sides of which, however, are more rarely convex. The hypohteca is trapezoidal, sometimes with a slightly rounded pole.
The plate-sutures bear thin, but relatively high ribs with finely denticulate rims. The transverse furrow as well (but not always) bears fine denticulations on its rim. On the hypotheca, the plate-sutures lenghten gonally into short denticulate horns, the development of which varies per specimen.
The epitheca has six preequatorial plates, the sixth of which is clearly more reduced than the others. Three apical plates join to form the tubular apical horn; one, adjacent to the sixth preequatorial plate, is situated in line with the longitudinal furrow, the others are adjacent to the preequatorials 1-2-3 and 3-4-5 respectively, their sutural line clearly running into the area of the upper part of of the third preequatorial. In all specimens, the third preequatorial is missing.
The hypotheca has six postequatorial plates, one polygonal antapical plate and an inermediate. The first postequatorial plate (1''') is very reduced and remains easily unnoticed. The intermediate plate (1p) is adjacent to the second and third preequatorial (sic, should be: postequatorial), to the antapical plate and the longitudinal furrow. The sutural ribs between plates 2-3, 3-4, 4-5 and 5-6 lengthen, as described earlier, into four denticulate horns, sometimes very reduced, sometimes very well developed. Some specimens of G. jurassica, until now rarely, have a fifth horn, situated on the suture 2-3, at the corner of plates 2''' and 1p.
The general form of G. jurassica mainly varies from bulging specimens with convex sides to specimens with concave sides.
The membrane on most specimens appears to be smooth or at the most finely punctate.
Dimensions: holotype 79x55 Ám. Range: length 60-100 Ám.
Supplemental description: Pocock, 1972, p.88
Vesicle longer than it is broad; epitheca hemispherical; terminated by a prominent, blunt-tipped horn made up of three elongate thecal plates (1', 2', and 3'); equatorial furrow well developed, helicoidal; hypotheca hemispherical; longitudinal furrow widest towards the antapex, narrowing to a point on the epitheca were it abuts against the antapical end of plate 1'; tabulation 3', 6", 6''', 1''''; sutures well defined, forming relatively wide ridges, usually finely serrate at their crests; test thin-walled; smooth; colourlless to pale yellow; length of test (inclusive of apical horn and crest to plate 1'''') 103.0--105 Ám (ridges shortest at equator; longest on plate 1'''').
Emended diagnosis: Sarjeant, 1982, p. 30
Cyst irregularly hexagonal to rounded-hexagonal in ambitus, prolonged apically into a mamelon or horn of highly variable length. Epitract in the form of a cone truncated at one-half to two-thirds height; hypotract smaller, in the form of an inverted cone truncated at one-third to one-half its height. Flanks of epitract and hypotract convex, planar or slightly concave. Epipericoel consistently developed, sometimes entirely confined to the horn, more often also occupying the apical region of the cyst to a varying degree; a hypopericoel may be present, developed only marginally, or completely lacking. Paraplates well marked by low to moderately high crests of variable form-irregularly to regularly serrate, denticulate, echinate or acanthate; crenellate, hystricate or phractate; or exhibiting complex intermediates between these types. Gonal spines present or absent, sometimes longest at the antapex and sustaining caudiculae. Paratabulation 2pa, 4', 2a, 6'', 6c, 6''', 1p, 1pv, 1''''. Paraplate 4' is elongate, less long than 1', with only a small contact with an elongate triangular 6''. The crests separating 4' from 6'' intersects the right lateral crest of 1' in a position markedly anterior to the junction of the latter paraplate with the sulcus. Archaeopyle single-plate precingular, formed by loss of paraplate 3'''; an opisthopyle may be developed in paraplate 1pv of delphicavate or bicavate specimens.
Affinities:
Pocock, 1972, p. 88: The Canadian specimens are larger, on average, than European ones, but there can be little doubt as to their identity. The smoothly ovoid test with prominent apical horn, wide sutural ridges and comparatively simple plating are characteristic of this species.