Back
Gonyaulacysta nealei
Gonyaulacysta? nealei (Sarjeant, 1962) Sarjeant, 1966
Now Rhynchodiniopsis?. Originally Gonyaulax, subsequently Gonyaulacysta (combination not validly published), thirdly Hystrichogonyaulax, fourthly Hystrichogonyaulax?, fifthly Rhynchodiniopsis, sixthly (and now) Rhynchodiniopsis?.
Combination not validly published since Sarjeant, 1966, did not fully reference the basionym.
Sarjeant, 1966, questionably included the species in Gonyaulacysta.
Holotype: Sarjeant, 1962, pl.69, fig.1; text-fig.2
Age: Oxfordian
Original description of Sarjeant, 1962:
Gonyaulax nealei sp. Nov.
Holotype: M134/3/172, 62-foot horizon of Ampthill Clay, Melton. Dimensions of Type. Overall: length 69 µm, breadth 61 µm. Without spines: length 64 µm, breadth 50 µm. Spines up to 5 µm in length. Other specimens too damaged for satisfactory measurement.
Diagnosis: A species of fossil Gonyaulax with epitheca conical, rounded at the apex, and hypotheca in the form of a truncated cone. Tabulation 6’, 1a, 6’’, 6’’’, 2p, 1’’’’: Plate 1’’’reduced and elongate. Sutures in the form of low ridges generally bearing simple spines of varying length and quite wide separation; the apical sutures, however, lack spines.
Description: Theca pale yellowish in colour, thin walled and without granulation. There is not apical horn: the six apical plates differ from those of the rest of the theca in that the sutures between them lack spines, whereas the sutures separating them from the other epithecal plates are spinose. One anterior intercalary plate and six pre-equatorial plates are present: plates 1’’ and 6’’ are somewhat reduced. The transverse furrow is of moderate breadth and extends round the theca in a laevo-rotatory spiral such that its two ends differ in antero-posterior position by twice the width of the furrow. The longitudinal furrow is narrow in its epithecal portion but broadens as it approaches the antapex. Of the sic post-equatorial plates, plates 1’’’is very reduced and not readily seen, and plates 2’’’and 6’’’are also somewhat reduced. The large posterior intercalary plates are certainly present: a third (marked ‘?’) may also be present in the angle formed by plate 1p against plate 2’’’and the longitudinal furrow, but this could not be confirmed. The antapical plate is large and polygonal in shape.
The species is named after Dr. J. W. Neale of the Geology Department, University of Hull.
Remarks: Of the six specimens seen, only the holotype is well enough reserved to be capable of full study. In shape, tabulation, and ornamentation of crests, Gonyaulax nealei differs from all described fossil species. Those most closely comparable are Gonyaulax cornigera Valensi 1953, from the Bathonian of France, and G. serrata Cookson & Eisenack 1958, from Upper Jurassic to ?Neocomian of Western Australia. In neither of these species is the tabulation fully known; the former is distinguished by its longer and sometimes bifurcate sutural spines, the latter by the possession of grouped bifurcate processes of the apex.
Now Rhynchodiniopsis?. Originally Gonyaulax, subsequently Gonyaulacysta (combination not validly published), thirdly Hystrichogonyaulax, fourthly Hystrichogonyaulax?, fifthly Rhynchodiniopsis, sixthly (and now) Rhynchodiniopsis?.
Combination not validly published since Sarjeant, 1966, did not fully reference the basionym.
Sarjeant, 1966, questionably included the species in Gonyaulacysta.
Holotype: Sarjeant, 1962, pl.69, fig.1; text-fig.2
Age: Oxfordian
Original description of Sarjeant, 1962:
Gonyaulax nealei sp. Nov.
Holotype: M134/3/172, 62-foot horizon of Ampthill Clay, Melton. Dimensions of Type. Overall: length 69 µm, breadth 61 µm. Without spines: length 64 µm, breadth 50 µm. Spines up to 5 µm in length. Other specimens too damaged for satisfactory measurement.
Diagnosis: A species of fossil Gonyaulax with epitheca conical, rounded at the apex, and hypotheca in the form of a truncated cone. Tabulation 6’, 1a, 6’’, 6’’’, 2p, 1’’’’: Plate 1’’’reduced and elongate. Sutures in the form of low ridges generally bearing simple spines of varying length and quite wide separation; the apical sutures, however, lack spines.
Description: Theca pale yellowish in colour, thin walled and without granulation. There is not apical horn: the six apical plates differ from those of the rest of the theca in that the sutures between them lack spines, whereas the sutures separating them from the other epithecal plates are spinose. One anterior intercalary plate and six pre-equatorial plates are present: plates 1’’ and 6’’ are somewhat reduced. The transverse furrow is of moderate breadth and extends round the theca in a laevo-rotatory spiral such that its two ends differ in antero-posterior position by twice the width of the furrow. The longitudinal furrow is narrow in its epithecal portion but broadens as it approaches the antapex. Of the sic post-equatorial plates, plates 1’’’is very reduced and not readily seen, and plates 2’’’and 6’’’are also somewhat reduced. The large posterior intercalary plates are certainly present: a third (marked ‘?’) may also be present in the angle formed by plate 1p against plate 2’’’and the longitudinal furrow, but this could not be confirmed. The antapical plate is large and polygonal in shape.
The species is named after Dr. J. W. Neale of the Geology Department, University of Hull.
Remarks: Of the six specimens seen, only the holotype is well enough reserved to be capable of full study. In shape, tabulation, and ornamentation of crests, Gonyaulax nealei differs from all described fossil species. Those most closely comparable are Gonyaulax cornigera Valensi 1953, from the Bathonian of France, and G. serrata Cookson & Eisenack 1958, from Upper Jurassic to ?Neocomian of Western Australia. In neither of these species is the tabulation fully known; the former is distinguished by its longer and sometimes bifurcate sutural spines, the latter by the possession of grouped bifurcate processes of the apex.