Back
Meiourogonyaulax cristulata
Meiourogonyaulax cristulata (Sarjeant, 1959, p.332-334, pl.13, fig.2; text-fig.2) Sarjeant, 1969, p.14.
Originally Gonyaulax? (motile stage), subsequently Meiourogonyaulax?, thirdly Lithodinia?, fourthly (and now) Meiourogonyaulax, fifthly Lithodinia. This species is here retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83). Questionable assignment: Sarjeant (1969, p.14) - however, Stover and Evitt (1978, p.63) retained it in Meiourogonyaulax without question. This combination was not validly published in Sarjeant (1966b, p.146), since that author did not fully reference the basionym.
Holotype: Sarjeant, 1959, pl.13, fig.2; text-fig.2.
Age: Early Callovian.
Original diagnosis: Sarjeant, 1959, p.332: Gonyaulax? cristula
A species of fossil dinoflagellate having an oval theca, longer than broad, with the tabulation 1+" (sic), 6", ?1a, 5""", 1p and small triangular plate, 1"""", and without an apical horn. Sutures ornamented by moderately high crests, in part perforate.
Dimensions: Type: Length 59 µm, breadth 50 µm, height of crests around 2 µm, width of transverse furrow around 4 µm. These dimensions are rather smaller than average: the largest specimen seen was 70 µm broad.
Affinities:
Sarjeant, 1959, p.334: Gonyaulax? cristula
This species differs from all existing dinoflagellate genera in its tabulation. The present-day genus Congruen has the tabulation 4", 1a, 5", 5""", 1p, 2"""": however, the smaller number of pre-equatorial plates and the possession of two antapical plates are important differences. The tabulation of Gonyaulax specifies one more post-equatorial plate; however, the large plate 5""" of this species may well be formed by fusion of plates 5""" and 6""" of Gonyaulax and it is therefore referred to this genus.
?G. cristulata resembles G. caytonensis in the form of its crests but differs from the latter species in general shape: the absence of plate 6""": the presence of plate 1p and the small triangular hypothecal plate: the smaller height of the crests: the form of the longitudinal furrow: and the presence of a suture dividing the transverse furrow between plates 6" and 5""".
Only three fossil species of Gonyaulax have so farbeen described which lack any terminal horn or spine, G. aceras, Aptian, Germany (Eisenack), G. amabilis, Kimmeridgian, France, (Deflandre) and G. porosa, Cretaceous, Belgium (Lejeune-Carpentier). The new species differ markedly from these.
Originally Gonyaulax? (motile stage), subsequently Meiourogonyaulax?, thirdly Lithodinia?, fourthly (and now) Meiourogonyaulax, fifthly Lithodinia. This species is here retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83). Questionable assignment: Sarjeant (1969, p.14) - however, Stover and Evitt (1978, p.63) retained it in Meiourogonyaulax without question. This combination was not validly published in Sarjeant (1966b, p.146), since that author did not fully reference the basionym.
Holotype: Sarjeant, 1959, pl.13, fig.2; text-fig.2.
Age: Early Callovian.
Original diagnosis: Sarjeant, 1959, p.332: Gonyaulax? cristula
A species of fossil dinoflagellate having an oval theca, longer than broad, with the tabulation 1+" (sic), 6", ?1a, 5""", 1p and small triangular plate, 1"""", and without an apical horn. Sutures ornamented by moderately high crests, in part perforate.
Dimensions: Type: Length 59 µm, breadth 50 µm, height of crests around 2 µm, width of transverse furrow around 4 µm. These dimensions are rather smaller than average: the largest specimen seen was 70 µm broad.
Affinities:
Sarjeant, 1959, p.334: Gonyaulax? cristula
This species differs from all existing dinoflagellate genera in its tabulation. The present-day genus Congruen has the tabulation 4", 1a, 5", 5""", 1p, 2"""": however, the smaller number of pre-equatorial plates and the possession of two antapical plates are important differences. The tabulation of Gonyaulax specifies one more post-equatorial plate; however, the large plate 5""" of this species may well be formed by fusion of plates 5""" and 6""" of Gonyaulax and it is therefore referred to this genus.
?G. cristulata resembles G. caytonensis in the form of its crests but differs from the latter species in general shape: the absence of plate 6""": the presence of plate 1p and the small triangular hypothecal plate: the smaller height of the crests: the form of the longitudinal furrow: and the presence of a suture dividing the transverse furrow between plates 6" and 5""".
Only three fossil species of Gonyaulax have so farbeen described which lack any terminal horn or spine, G. aceras, Aptian, Germany (Eisenack), G. amabilis, Kimmeridgian, France, (Deflandre) and G. porosa, Cretaceous, Belgium (Lejeune-Carpentier). The new species differ markedly from these.