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Tehamadinium evittii
Tehamadinium evittii (Dodekova, 1969) Jan du Chene et al. in Jan du Chene et al., 1986a; emend. Jan du Chene et al., 1986b
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.
This combination was not validly published in Jan du Chêne et al. (1986a, p.352), since the generic name Tehamadinium was not validly published.
Holotype: Dodekova, 1969, pl.1, fig.1-2; Jan du Chene et al., 1986a, pl. 177, fig.1-2; Jan du Chene et al., 1986b, pl. 20, fig. 1-4
Paratypes: Dodekova, 1969; Jan du Chene et al., 1986
Locus typicus: Village of Dolen Dabnik, Well R1, Central N Bulgaria
Stratum typicum: Tithonian
Translation Dodekova, 1969: LPP
Translation Jan du Chene, 1986: LPP
Original description: Dodekova, 1969, p. 14-15 for Gonyaulacysta evittii
Spherical, nearly ellipsoidal theca, divided in two halves by a aevorotatory 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 (µm): holotype: length 82, width 82, crests 4, apical horn 8; paratypes: length 81, 85, width 81, 85, crests 4, 4-8, apical horn 8, 11.
Emended description: Jan du Chene et al., 1986, p. 20-21
Proximate dinoflagellate cyst, subspherical to ellipsoidal, bearing a small apical protuberance. The paratabulation is gonyaulacoid 1pr, 4", 6"", 6c, 5s, 6""", 1p, 1"""". The autophragm is chagrinate or vacuolar,and is supported by fine, perforate parasutural septa, with irregularly denticulate crests. This species is characterized by the presence of accessory septa, parallel to the parasutural septa, and formed by alignments of spines or verrucae. Archaeopyle precingular, type 2P(2""+3""), operculum composite, free. The paracingulum is lightly laevorotatory. The septa delimiting the parasulcus as well as the parasulcal plates are of moderate height.
Emended description: proximate dinoflagellate cyst, subspherical to ellipsoidal, bearing a small apical protuberance, formed by the junctions of the septa delimiting the apical plates. The paratabulation is gonyaulacoid 1pr, 4", 6"", 6c, 5s, 6""", 1p, 1"""", indicated by the irregularly fenestrate or perforate septa variable height, carrying finely denticulate crests. Accessory septa, parallel to the parasutural septa, but generally less elevated, characterize this species. These accessory septa are formed by alignments of spines or verrucae. The intratabular areas are grossly chagrinate or vacuolar. The archaeopyle is precingular, type 2P (2""+3""), with a composite, free operculum. The paracingulum is lightly laevorotatory. The septa delimiting the parasulcus as well as the parasulcal plates are of moderate height.
Affinities:
Dodekova, 1969, p. 14: The tabulation, the "double sutures", on the plates, and especially the archaeopyle, which is a characteristic of the species, clearly distinguish G. evittii from the other representatives of the genus.
Jan du Chene et al. in Jan du Chene et al., 1986, p. 352: T. evittii and T. brixii both have accessory septa, and do not posses intratabular ornamentation in the form of spines. T. evittii (> 80 µm) is larger than T. brixii (< 70 µm). The parasutural septa in T. brixii consist of alignments of distally regularly connected arches. In T. evittii, the parasutural septa are delicate and irregularly perforate. T. sousensis resembles T. evittii in the vacuolar nature of the autophragm, the faint intratabular ornamentation and the structure of the parasutural septa, but does not possess accessory septa.
T. dodekovae is of equal size and shape as T. evittii, but is characterized by a dense, spinous, intratabular ornamentation.
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.
This combination was not validly published in Jan du Chêne et al. (1986a, p.352), since the generic name Tehamadinium was not validly published.
Holotype: Dodekova, 1969, pl.1, fig.1-2; Jan du Chene et al., 1986a, pl. 177, fig.1-2; Jan du Chene et al., 1986b, pl. 20, fig. 1-4
Paratypes: Dodekova, 1969; Jan du Chene et al., 1986
Locus typicus: Village of Dolen Dabnik, Well R1, Central N Bulgaria
Stratum typicum: Tithonian
Translation Dodekova, 1969: LPP
Translation Jan du Chene, 1986: LPP
Original description: Dodekova, 1969, p. 14-15 for Gonyaulacysta evittii
Spherical, nearly ellipsoidal theca, divided in two halves by a aevorotatory 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 (µm): holotype: length 82, width 82, crests 4, apical horn 8; paratypes: length 81, 85, width 81, 85, crests 4, 4-8, apical horn 8, 11.
Emended description: Jan du Chene et al., 1986, p. 20-21
Proximate dinoflagellate cyst, subspherical to ellipsoidal, bearing a small apical protuberance. The paratabulation is gonyaulacoid 1pr, 4", 6"", 6c, 5s, 6""", 1p, 1"""". The autophragm is chagrinate or vacuolar,and is supported by fine, perforate parasutural septa, with irregularly denticulate crests. This species is characterized by the presence of accessory septa, parallel to the parasutural septa, and formed by alignments of spines or verrucae. Archaeopyle precingular, type 2P(2""+3""), operculum composite, free. The paracingulum is lightly laevorotatory. The septa delimiting the parasulcus as well as the parasulcal plates are of moderate height.
Emended description: proximate dinoflagellate cyst, subspherical to ellipsoidal, bearing a small apical protuberance, formed by the junctions of the septa delimiting the apical plates. The paratabulation is gonyaulacoid 1pr, 4", 6"", 6c, 5s, 6""", 1p, 1"""", indicated by the irregularly fenestrate or perforate septa variable height, carrying finely denticulate crests. Accessory septa, parallel to the parasutural septa, but generally less elevated, characterize this species. These accessory septa are formed by alignments of spines or verrucae. The intratabular areas are grossly chagrinate or vacuolar. The archaeopyle is precingular, type 2P (2""+3""), with a composite, free operculum. The paracingulum is lightly laevorotatory. The septa delimiting the parasulcus as well as the parasulcal plates are of moderate height.
Affinities:
Dodekova, 1969, p. 14: The tabulation, the "double sutures", on the plates, and especially the archaeopyle, which is a characteristic of the species, clearly distinguish G. evittii from the other representatives of the genus.
Jan du Chene et al. in Jan du Chene et al., 1986, p. 352: T. evittii and T. brixii both have accessory septa, and do not posses intratabular ornamentation in the form of spines. T. evittii (> 80 µm) is larger than T. brixii (< 70 µm). The parasutural septa in T. brixii consist of alignments of distally regularly connected arches. In T. evittii, the parasutural septa are delicate and irregularly perforate. T. sousensis resembles T. evittii in the vacuolar nature of the autophragm, the faint intratabular ornamentation and the structure of the parasutural septa, but does not possess accessory septa.
T. dodekovae is of equal size and shape as T. evittii, but is characterized by a dense, spinous, intratabular ornamentation.