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Rhynchodiniopsis aptiana
Rhynchodiniopsis *aptiana Deflandre, 1935, p.231, pl.5, fig.10; pl.8, figs.7–10. Emendation: Sarjeant, 1982b, p.36–37.
Originally (and now) Rhynchodiniopsis, subsequently Gonyaulacysta. Lentin and Williams (1973, p.121) retained this species in Rhynchodiniopsis. Taxonomic junior synonym: Gonyaulacysta fimbriata, according to Below (1981a, p.118) — however, Sarjeant (1982b, p.35) retained Gonyaulacysta (as Rhynchodiniopsis) fimbriata. Jan du Chêne et al. (1986a, p.286) indicated that this species was emended by Stover and Evitt (1978, p.278–279); however, those authors did not indicate that they were emending the species.
Holotype: Deflandre, 1935, pl.5, fig.10; pl.8, figs.7–9; Deflandre, 1936b, pl.7, figs.2–4.
Age: Senonian.
Original description: Deflandre, 1935, p. 231; improved description Deflandre, 1936, p. 180
Diagnosis (Deflandre, 1936): In frontal view, the theca is clearly hexagonal,the upper part mounted by a strongly cylindrical or subcylindrical horn. The epitheca and hypotheca are of approximately equal size. The epitheca has the form of a truncate pyramid, the upper plane consisting of two apical plates, one of which bears the horn. The horn, as far as one can judge, consists of a single piece, and stems from the second apical plate (the first apical is formed by the top of the longitudinal furrow). A very small, invariable, rectangular intercalary plate connects the third apical and the third pre-equatorial, which is situated dorsally. The six pre-equatorials are connected by sutures bearing strong, aliform, denticulate crests, ending towards the transverse furrow in a strong, often crooked thorn. The tabulation of the hypotheca is less well known. There seem to be two, nearly equal antapicals, about as large as the second and third apicals, and probably six post-equatorial plates, trapezoidal, like the pre-equatorials. The sutures are evenly provided with crests, and thorns where they meet the transverse furrow. The latter is laevorotatory, and enclosed by two strongly denticulate crests. It consists of several (six?) plates, of which the sutures standing at a right angle to the furrow sometimes cause narrowings, which give the plates a hexagonal appearance. Sometimes there seems to be a resemblance with the equatorial plates of Hystrichosphaera. The longitudinal furrow is well-developed and seems to extend from apex to antapex. The membrane is reticulate and often granulate or chagrinate, and yellowish.
Dimensions: Total length 90-100 µm, total width 60-75 µm.
Emended diagnosis: Sarjeant, 1982, p. 37
Cyst of moderate size, irregularly hexagonal to rounded-hexagonal in ambitus, prolonged apically into a mamelon or horn of variable (but never great) length. Epitract (horn excluded) and hypotract of almost equal size and similar shape, each having the form of a steep-sided cone truncated at about half to two-thirds its height. Flanks of epitract and hypotract planar to convex or (rarely) shallowly concave. Epipericoel consistently developed, typically confined to the horn and sometimes restricted to the horn tip (cornucavate to acrocavate); wall layers otherwise in continuous contact. Parasututures marked by ridges or giving rise to crests of variable character, typically denticulate to echinate, with denticles and spines of varying height and spacing, but in some specimens of more irregular form. Gonal spinules present, longer than the crests. Paratabulation 2pa, 4", 1-2a, 6"", 6c, 6""", 1p, ?0pv, 1"""". Paraplate 4" is almost trapezoidal, with longer sides bordering 3" and 1" and shorter sides bordering 5"" and 6"", its contact with the latter being nevertheless considerable. Its boundary with 6"" intersects the right lateral boundary of 1" in a position anterior to the junction of the latter paraplate with the sulcus. Paraplate 6"" is relatively small and pentagonal. archaeopyle single-plated precingular, formed by loss of paraplate 3""; operculum reduced.
Originally (and now) Rhynchodiniopsis, subsequently Gonyaulacysta. Lentin and Williams (1973, p.121) retained this species in Rhynchodiniopsis. Taxonomic junior synonym: Gonyaulacysta fimbriata, according to Below (1981a, p.118) — however, Sarjeant (1982b, p.35) retained Gonyaulacysta (as Rhynchodiniopsis) fimbriata. Jan du Chêne et al. (1986a, p.286) indicated that this species was emended by Stover and Evitt (1978, p.278–279); however, those authors did not indicate that they were emending the species.
Holotype: Deflandre, 1935, pl.5, fig.10; pl.8, figs.7–9; Deflandre, 1936b, pl.7, figs.2–4.
Age: Senonian.
Original description: Deflandre, 1935, p. 231; improved description Deflandre, 1936, p. 180
Diagnosis (Deflandre, 1936): In frontal view, the theca is clearly hexagonal,the upper part mounted by a strongly cylindrical or subcylindrical horn. The epitheca and hypotheca are of approximately equal size. The epitheca has the form of a truncate pyramid, the upper plane consisting of two apical plates, one of which bears the horn. The horn, as far as one can judge, consists of a single piece, and stems from the second apical plate (the first apical is formed by the top of the longitudinal furrow). A very small, invariable, rectangular intercalary plate connects the third apical and the third pre-equatorial, which is situated dorsally. The six pre-equatorials are connected by sutures bearing strong, aliform, denticulate crests, ending towards the transverse furrow in a strong, often crooked thorn. The tabulation of the hypotheca is less well known. There seem to be two, nearly equal antapicals, about as large as the second and third apicals, and probably six post-equatorial plates, trapezoidal, like the pre-equatorials. The sutures are evenly provided with crests, and thorns where they meet the transverse furrow. The latter is laevorotatory, and enclosed by two strongly denticulate crests. It consists of several (six?) plates, of which the sutures standing at a right angle to the furrow sometimes cause narrowings, which give the plates a hexagonal appearance. Sometimes there seems to be a resemblance with the equatorial plates of Hystrichosphaera. The longitudinal furrow is well-developed and seems to extend from apex to antapex. The membrane is reticulate and often granulate or chagrinate, and yellowish.
Dimensions: Total length 90-100 µm, total width 60-75 µm.
Emended diagnosis: Sarjeant, 1982, p. 37
Cyst of moderate size, irregularly hexagonal to rounded-hexagonal in ambitus, prolonged apically into a mamelon or horn of variable (but never great) length. Epitract (horn excluded) and hypotract of almost equal size and similar shape, each having the form of a steep-sided cone truncated at about half to two-thirds its height. Flanks of epitract and hypotract planar to convex or (rarely) shallowly concave. Epipericoel consistently developed, typically confined to the horn and sometimes restricted to the horn tip (cornucavate to acrocavate); wall layers otherwise in continuous contact. Parasututures marked by ridges or giving rise to crests of variable character, typically denticulate to echinate, with denticles and spines of varying height and spacing, but in some specimens of more irregular form. Gonal spinules present, longer than the crests. Paratabulation 2pa, 4", 1-2a, 6"", 6c, 6""", 1p, ?0pv, 1"""". Paraplate 4" is almost trapezoidal, with longer sides bordering 3" and 1" and shorter sides bordering 5"" and 6"", its contact with the latter being nevertheless considerable. Its boundary with 6"" intersects the right lateral boundary of 1" in a position anterior to the junction of the latter paraplate with the sulcus. Paraplate 6"" is relatively small and pentagonal. archaeopyle single-plated precingular, formed by loss of paraplate 3""; operculum reduced.