Back
Gonyaulacysta kleithria
GonyauIacysta? kleithria Duxbury 1983
Duxbury, 1983, questionably included this species in Gonyaulacysta.
Holotype: Duxbury, 1983, text-fig.22
Paratype: Duxbury, pl.5, figs.1,2
Locus typicus: Atherfield section, Isle of Wight, England
Stratum typicum: Early Aptian
Original diagnosis: Duxbury, 1983, p. 47
A fairly large, partially cavate, gonyaulacacean dinoflagellate cyst species. The smooth endocyst is approximately square in outline and has a distinct, distally rounded and closed apical projection. The pericyst, which is also smooth, is in contact with the endocyst only on the dorsal surface and is produced into a well-developed, staight or concave-sided, open apical horn. Paratabulation of the formula 4", 1a.s., 6", ?c, 5""", 1p., 1p.v., 1"""" is marked on the periocoel surface by low crests which are distally irregularly denticulate. An irregular hole is observed in the ventral pericoel, presumably marking the parasulcus. An archeopyle is formed by detachment of paraplate 3".
Observed Dimensions: Holotype 67x67 Ám. Overall 78(67)55x73(58)46 Ám.
Affinities:
Duxbury, 1983, p.48: The placement of this species in Gonyaulacysta is only tentative since there is a characteristic cavation which is invariably observed over the whole surface other than the dorsal area. In all respects other than the cavation, the morphology of this species is typical of the genus Gonyaulacysta.
The irregular hole which is always present in the ventral pericoel presumably represents the parasulcus. It is noteworthy that the area where paraplate 1""" (in conventional gonyaulacacean schemes) would normally be found is incorporated within the hole. This homology of paraplate 1""" (in the conventional sense) with part of the parasulcus was also noted in Aptea plera Duxbury and was discussed in the remarks under that species (above). The obvious conclusion from this observation is that the paraplate which has up to now been termed 1""" is truly parasulcal and the paratabulation of G? kleithria has been interpreted accordingly here (see Text-Fig. 22).
Duxbury, 1983, questionably included this species in Gonyaulacysta.
Holotype: Duxbury, 1983, text-fig.22
Paratype: Duxbury, pl.5, figs.1,2
Locus typicus: Atherfield section, Isle of Wight, England
Stratum typicum: Early Aptian
Original diagnosis: Duxbury, 1983, p. 47
A fairly large, partially cavate, gonyaulacacean dinoflagellate cyst species. The smooth endocyst is approximately square in outline and has a distinct, distally rounded and closed apical projection. The pericyst, which is also smooth, is in contact with the endocyst only on the dorsal surface and is produced into a well-developed, staight or concave-sided, open apical horn. Paratabulation of the formula 4", 1a.s., 6", ?c, 5""", 1p., 1p.v., 1"""" is marked on the periocoel surface by low crests which are distally irregularly denticulate. An irregular hole is observed in the ventral pericoel, presumably marking the parasulcus. An archeopyle is formed by detachment of paraplate 3".
Observed Dimensions: Holotype 67x67 Ám. Overall 78(67)55x73(58)46 Ám.
Affinities:
Duxbury, 1983, p.48: The placement of this species in Gonyaulacysta is only tentative since there is a characteristic cavation which is invariably observed over the whole surface other than the dorsal area. In all respects other than the cavation, the morphology of this species is typical of the genus Gonyaulacysta.
The irregular hole which is always present in the ventral pericoel presumably represents the parasulcus. It is noteworthy that the area where paraplate 1""" (in conventional gonyaulacacean schemes) would normally be found is incorporated within the hole. This homology of paraplate 1""" (in the conventional sense) with part of the parasulcus was also noted in Aptea plera Duxbury and was discussed in the remarks under that species (above). The obvious conclusion from this observation is that the paraplate which has up to now been termed 1""" is truly parasulcal and the paratabulation of G? kleithria has been interpreted accordingly here (see Text-Fig. 22).