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Gonyaulax heslertonensis
Gonyaulax heslertonensis Neale and Sarjeant 1962; Emendation: Duxbury, 1980, p.124, as Heslertonia heslertonensis
Now Heslertonia. Originally Gonyaulax, subsequently (and now) Heslertonia.
Holotype: Neale and Sarjeant, 1962, pl.19, fig.5, text-fig.1
Paratype: Neale and Sarjeant, 1962
Locus typicus: Speeton Clay, Heslterton, England
Stratum typicum: Hauterivian-Barremian
Original diagnosis: Neale and Sarjeant, 1962, p. 43-44
A species of fossil Conyaulax having a theca of rounded pntagonal outline, with epithecn conicnl and hypotheca truncated conical. Tabulations 5", 6"", 6-?7""", ?1p, 1"""". Transverse furrow strongly spiral, laevo-rotatory, divided by low ridges into sections (?6). Crests on plate and furrow boundaries high and delicate.
Original description: Neale and Sarjeant, 1962, p.45
Shell deep yellow in colour, not granulate or punctate. Crests very pale yellow, delicate and frequently folded: in part or constantly, they bifurcate distally in T or Y fashion and have denticulate or smooth edges. Five apical plates; plate 1" is elongate, its anterior portion occupying the apex. Six pre-equatorial plates, plate 1 being somewhat reduced: no anterior intercalary plates present. The transverse furrow is strongly spiral, its two ends differing in antero-posterior position by more than three times the furrow"s breadth. The longitudinal furrow is of moderate breadth and extends from the antapical plate to meet plate 1" halfway up the epitheca. Structure of the hypotheca less clear: apparently seven post-equatorial plates, with plates 1""" and 7""" reduced: a posterior intercalary plate present, posterior to plate 1""". A single polygonal plate occupies the antapex.
Dimensions: Overall length 64 µm, breadth 64 µm: shell length 36 µm, breadth 37.5 µm.
Affinities:
Neale and Sarjeant, 1962, p. 45: This species differs from all deseribed fossil species of Gonyaulax in the character of its crests. A resemblance exists to the genus Pterodinium Eisenack 1958, which also has high crests and whose tabulation has not been specified: however, G. heslertonense differs in outline and crest character from all described species and forms of Eisenack"s genus.
Now Heslertonia. Originally Gonyaulax, subsequently (and now) Heslertonia.
Holotype: Neale and Sarjeant, 1962, pl.19, fig.5, text-fig.1
Paratype: Neale and Sarjeant, 1962
Locus typicus: Speeton Clay, Heslterton, England
Stratum typicum: Hauterivian-Barremian
Original diagnosis: Neale and Sarjeant, 1962, p. 43-44
A species of fossil Conyaulax having a theca of rounded pntagonal outline, with epithecn conicnl and hypotheca truncated conical. Tabulations 5", 6"", 6-?7""", ?1p, 1"""". Transverse furrow strongly spiral, laevo-rotatory, divided by low ridges into sections (?6). Crests on plate and furrow boundaries high and delicate.
Original description: Neale and Sarjeant, 1962, p.45
Shell deep yellow in colour, not granulate or punctate. Crests very pale yellow, delicate and frequently folded: in part or constantly, they bifurcate distally in T or Y fashion and have denticulate or smooth edges. Five apical plates; plate 1" is elongate, its anterior portion occupying the apex. Six pre-equatorial plates, plate 1 being somewhat reduced: no anterior intercalary plates present. The transverse furrow is strongly spiral, its two ends differing in antero-posterior position by more than three times the furrow"s breadth. The longitudinal furrow is of moderate breadth and extends from the antapical plate to meet plate 1" halfway up the epitheca. Structure of the hypotheca less clear: apparently seven post-equatorial plates, with plates 1""" and 7""" reduced: a posterior intercalary plate present, posterior to plate 1""". A single polygonal plate occupies the antapex.
Dimensions: Overall length 64 µm, breadth 64 µm: shell length 36 µm, breadth 37.5 µm.
Affinities:
Neale and Sarjeant, 1962, p. 45: This species differs from all deseribed fossil species of Gonyaulax in the character of its crests. A resemblance exists to the genus Pterodinium Eisenack 1958, which also has high crests and whose tabulation has not been specified: however, G. heslertonense differs in outline and crest character from all described species and forms of Eisenack"s genus.