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Gonyaulacysta evittii
Gonyaulacysta evittii Dodekova, 1969, p.14–15, pl.1, figs.1–6; pl.2, figs.1–12; text-figs.Aa–b. Emendation: Jan du Chêne et al., 1986b, p.26–27, as Tehamadinium evittii.
NOW Tehamadinium. Originally Gonyaulacysta, subsequently Occisucysta, thirdly (and now) Tehamadinium.
Taxonomic junior synonym: Diacanthum hollisteri, according to Below (1982a, p.32–33) — however, Jan du Chêne et al. (1986b, p.122) and Habib and Drugg (1987, p.762–763) retained Diacanthum hollisteri.
Holotype: Dodekova, 1969, pl.1, fig.1-2; Jan du Chêne, Masure et al., 1986, pl.117, figs.1-2; Jan du Chêne et al., 1986, pl.20, figs.1-4
Paratypes: Dodekova, 1969
Locus typicus: Village of Dolen Dabnik, Well R1, Central N Bulgaria
Stratum typicum: Tithonian
Translation Dodekova, 1969: LPP
Original description: Dodekova, 1969, p. 14-15
Spherical, nearly ellipsoidal theca, divided in two halves by a laevorotatory transversal furrow. The two ends of the furrow are bent towards the antapex. The longitudinal furrow is deep, relatively short and very faintly ornamented.
The epitheca has a truncate conical form, with an apical horn of variable dimensions, which is formed by the sutural crests. The apex consists of 4 plates. The pre-equatorial region comprises 6 plates, of which the sixth plate is the smallest. The hypotheca is rounded, semispherical, consisting of 6 post-equatorial, clear and well-formed plates, 1p and 1ppl. In the post-equatorial region, there are traces of the formation of a new plate - 7""", which, by its dimensions, resembles 1""". It is delimited on three sides by crests, but remains open towards the longitudinal furrow. It differs from the longitudinal furrow by a more pronounced ornamentation of the membrane. The transverse furrow is clearly divided in 6 straight and elongate fields, but in the ventral equatorial region one finds another plate - 7s. This plate is very small and, similar to 7""", is open towards the longitudinal furrow. Thus, the tabulation is expressed with the scheme: 4", 6"", 6(7?)s.t., 6(7?)""", 1p, 1ppl, 1"""".
The presence of the seventh plate in the postequatorial region and next to the transverse furrow changes either the diagnosis of the genus Gonyaulacysta, or may offer the possibility to erect a new genus.
The sutures bear fine, folded, perforate crests, less frequently denticulate distally. Similar lamellae can be observed on the plates, parallel to the sutures, that is to say, the "double sutures". Their development differs from specimen to specimen.
The thecal membrane has a strongly pronounced, chagrinate relief. Small spines and verrucae from the "double sutures", or are arranged next to it. The archaeopyle os pre-equatorial, at the position of 2"" and 3"".
Dimensions: holotype: length 82 µm, width 82 µm, crests 4 µm, apical horn 8 µm; paratypes: length 81 µm, 85 µm, width 81 µm, 85 µm, crests 4 µm, 4-8 µm, apical horn 8 µm, 11 µm.
NOW Tehamadinium. Originally Gonyaulacysta, subsequently Occisucysta, thirdly (and now) Tehamadinium.
Taxonomic junior synonym: Diacanthum hollisteri, according to Below (1982a, p.32–33) — however, Jan du Chêne et al. (1986b, p.122) and Habib and Drugg (1987, p.762–763) retained Diacanthum hollisteri.
Holotype: Dodekova, 1969, pl.1, fig.1-2; Jan du Chêne, Masure et al., 1986, pl.117, figs.1-2; Jan du Chêne et al., 1986, pl.20, figs.1-4
Paratypes: Dodekova, 1969
Locus typicus: Village of Dolen Dabnik, Well R1, Central N Bulgaria
Stratum typicum: Tithonian
Translation Dodekova, 1969: LPP
Original description: Dodekova, 1969, p. 14-15
Spherical, nearly ellipsoidal theca, divided in two halves by a laevorotatory transversal furrow. The two ends of the furrow are bent towards the antapex. The longitudinal furrow is deep, relatively short and very faintly ornamented.
The epitheca has a truncate conical form, with an apical horn of variable dimensions, which is formed by the sutural crests. The apex consists of 4 plates. The pre-equatorial region comprises 6 plates, of which the sixth plate is the smallest. The hypotheca is rounded, semispherical, consisting of 6 post-equatorial, clear and well-formed plates, 1p and 1ppl. In the post-equatorial region, there are traces of the formation of a new plate - 7""", which, by its dimensions, resembles 1""". It is delimited on three sides by crests, but remains open towards the longitudinal furrow. It differs from the longitudinal furrow by a more pronounced ornamentation of the membrane. The transverse furrow is clearly divided in 6 straight and elongate fields, but in the ventral equatorial region one finds another plate - 7s. This plate is very small and, similar to 7""", is open towards the longitudinal furrow. Thus, the tabulation is expressed with the scheme: 4", 6"", 6(7?)s.t., 6(7?)""", 1p, 1ppl, 1"""".
The presence of the seventh plate in the postequatorial region and next to the transverse furrow changes either the diagnosis of the genus Gonyaulacysta, or may offer the possibility to erect a new genus.
The sutures bear fine, folded, perforate crests, less frequently denticulate distally. Similar lamellae can be observed on the plates, parallel to the sutures, that is to say, the "double sutures". Their development differs from specimen to specimen.
The thecal membrane has a strongly pronounced, chagrinate relief. Small spines and verrucae from the "double sutures", or are arranged next to it. The archaeopyle os pre-equatorial, at the position of 2"" and 3"".
Dimensions: holotype: length 82 µm, width 82 µm, crests 4 µm, apical horn 8 µm; paratypes: length 81 µm, 85 µm, width 81 µm, 85 µm, crests 4 µm, 4-8 µm, apical horn 8 µm, 11 µm.