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Montanarocysta mirabilis
Montanarocysta mirabilis (Below, 1984, p.635–636, pl.6, fig.2) Slimani, 2004, p.181,182. Emendation: Masure, 1988a, p.366–368, as Maghrebinia mirabilis.
Originally Maghrebinia perforata subsp. mirabilis, subsequently Maghrebinia mirabilis, thirdly Atopodinium mirabile, fourthly (and now) Montanarocysta mirabilis.
Holotype: Below, 1981a, pl.1, figs.1a–c, as Maghrebinia perforata; Masure, 1988a, pl.3, figs.1–11; text-figs.4a–c; Fauconnier and Masure, 2004, pl.10, figs.1–4.
Age: late Albian–early Cenomanian.
Original diagnosis: Below, 1984, p. 635: Maghrebinia perforata ssp. mirabilis
Chorate, somewhat lenticular cyst with bitrapezoidal size. Divided into a small epicyst and a greater hypocyst by an equatorial planispiral intratabular membrane. Paraplates bordered by high, distally denticulated, perforated or unperforated membranes, which are often irregularly and deeply slit. An apical area with few intratabular processes as well as the antapical, four precingular, and three postcingular paraplates are bordered by these septa. Nevertheless, the paraplate scheme could be 3"-?4", 5"", 0c, 4""", 1"""" because the large ventral area between polar plates is undifferentiated. The right end of the paracingulum extends into this area. The cyst surface is microfrangate (see Below, 1981, p. 23). Endophragmal gonal membranal thickening is often perforated. Archeopyle type [A].
Dimensions. Holotype: length 80 Ám; paratypes: length 62-96 Ám, breadth 60-90 Ám.
Modified description: Masure, 1991, p.70-71
Slightly dorsoventrally compressed subspheroidal, acavate, proximate dinocyst with polygonal outline. Thin wall composed of an autophragm or of an endophragm and a periphragm in close contact, with a smooth to faintly granulate surface. The flattened epicyst is considerably smaller than the hypocyst. A sexiform gonyaulacoid thecal tabulation is inferred. The paratabulation is incompletely and weakly delineated by low ridges/septa and grana. The paratabulation is composed of 0-2 preapical(s) (P,Q), 0-?1 anterior intercalary (K), 4 apicals (1u,B,C,A), 6 precingulars (1i, 2-6), X cingulars, 5-?6 postcingulars (?Iu, II-VI), ?l posterior intercalary (X), 1 antapical (Y) and X sulcals. The apex is slightly domed, with a small protuberance and apical paraplates are unornamented. The 6 precingulars are emphasized by accessory parasutures of the archeopyle. Two low septa mark the descending paracingulum. The ventral area is untabulated. The sulcal paraplates and the parasutures that are shared between the sulcus and the precingular (2, 1i), postcingular (Iu, II-VI), and postintercalary (X) paraplates are not expressed by surface features. Only four postcingular parasutures (II/III, III/IV, IV/V, V/VI) are erected by low septa. The smooth postcingular paraplates III, IV, V are of equal size and IV is Iying below the precingular 4, the postcingular contact IV/V is aligned with the precingular 4/5. The invagined antapical paraplate Y is broading from the dorsal surface to the ventral one (fan-shape). The dorsal contact IV/Y is shorter than the ventral contacts VI/Y, Z/Y, X/Y. The apical archeopyle is of (tA)a type, with precingular accessory parasutures. The polyplacoid, simple operculum is adnate to the sulcal ai, and the precingular 2 and 1i paraplates.
Dimensions. According to Beju (1983): (based on 25 specimens)--Maximum length 65-96 Ám, maximum width 58-94 Ám. This study: Holotype: length 63 Ám, width 60 Ám.
Affinities:
Below, 1984, p.636: Maghrebinia perforata ssp. mirabilis
The subspecies Maghrebinia perforata (Clarke and Verdier, 1967) Below, 1981 ssp. mirabilis n.ssp. differs from M. perforata (Clarke and Verdier, 1967) Below, 1981 ssp. perforata by its coarse and deep, irregular splitting of the high parasutural membranes. Septures of the letter subspecies are lower, are nearly constant in height, and are finely distally denticulated.
Two types of parasutural septa variations are now known: (1) the successive reduction of membrane height from M. perforata ssp. mirabilis to M. perforata ssp. perforata; (2) the second type is the interruption of membranes by deep splits and consequently the total absence of membranes between gonal thickenings, as occurs in the range of variation between M. perforata ssp. mirabilis and M. chleuh Below, 1981.
Originally Maghrebinia perforata subsp. mirabilis, subsequently Maghrebinia mirabilis, thirdly Atopodinium mirabile, fourthly (and now) Montanarocysta mirabilis.
Holotype: Below, 1981a, pl.1, figs.1a–c, as Maghrebinia perforata; Masure, 1988a, pl.3, figs.1–11; text-figs.4a–c; Fauconnier and Masure, 2004, pl.10, figs.1–4.
Age: late Albian–early Cenomanian.
Original diagnosis: Below, 1984, p. 635: Maghrebinia perforata ssp. mirabilis
Chorate, somewhat lenticular cyst with bitrapezoidal size. Divided into a small epicyst and a greater hypocyst by an equatorial planispiral intratabular membrane. Paraplates bordered by high, distally denticulated, perforated or unperforated membranes, which are often irregularly and deeply slit. An apical area with few intratabular processes as well as the antapical, four precingular, and three postcingular paraplates are bordered by these septa. Nevertheless, the paraplate scheme could be 3"-?4", 5"", 0c, 4""", 1"""" because the large ventral area between polar plates is undifferentiated. The right end of the paracingulum extends into this area. The cyst surface is microfrangate (see Below, 1981, p. 23). Endophragmal gonal membranal thickening is often perforated. Archeopyle type [A].
Dimensions. Holotype: length 80 Ám; paratypes: length 62-96 Ám, breadth 60-90 Ám.
Modified description: Masure, 1991, p.70-71
Slightly dorsoventrally compressed subspheroidal, acavate, proximate dinocyst with polygonal outline. Thin wall composed of an autophragm or of an endophragm and a periphragm in close contact, with a smooth to faintly granulate surface. The flattened epicyst is considerably smaller than the hypocyst. A sexiform gonyaulacoid thecal tabulation is inferred. The paratabulation is incompletely and weakly delineated by low ridges/septa and grana. The paratabulation is composed of 0-2 preapical(s) (P,Q), 0-?1 anterior intercalary (K), 4 apicals (1u,B,C,A), 6 precingulars (1i, 2-6), X cingulars, 5-?6 postcingulars (?Iu, II-VI), ?l posterior intercalary (X), 1 antapical (Y) and X sulcals. The apex is slightly domed, with a small protuberance and apical paraplates are unornamented. The 6 precingulars are emphasized by accessory parasutures of the archeopyle. Two low septa mark the descending paracingulum. The ventral area is untabulated. The sulcal paraplates and the parasutures that are shared between the sulcus and the precingular (2, 1i), postcingular (Iu, II-VI), and postintercalary (X) paraplates are not expressed by surface features. Only four postcingular parasutures (II/III, III/IV, IV/V, V/VI) are erected by low septa. The smooth postcingular paraplates III, IV, V are of equal size and IV is Iying below the precingular 4, the postcingular contact IV/V is aligned with the precingular 4/5. The invagined antapical paraplate Y is broading from the dorsal surface to the ventral one (fan-shape). The dorsal contact IV/Y is shorter than the ventral contacts VI/Y, Z/Y, X/Y. The apical archeopyle is of (tA)a type, with precingular accessory parasutures. The polyplacoid, simple operculum is adnate to the sulcal ai, and the precingular 2 and 1i paraplates.
Dimensions. According to Beju (1983): (based on 25 specimens)--Maximum length 65-96 Ám, maximum width 58-94 Ám. This study: Holotype: length 63 Ám, width 60 Ám.
Affinities:
Below, 1984, p.636: Maghrebinia perforata ssp. mirabilis
The subspecies Maghrebinia perforata (Clarke and Verdier, 1967) Below, 1981 ssp. mirabilis n.ssp. differs from M. perforata (Clarke and Verdier, 1967) Below, 1981 ssp. perforata by its coarse and deep, irregular splitting of the high parasutural membranes. Septures of the letter subspecies are lower, are nearly constant in height, and are finely distally denticulated.
Two types of parasutural septa variations are now known: (1) the successive reduction of membrane height from M. perforata ssp. mirabilis to M. perforata ssp. perforata; (2) the second type is the interruption of membranes by deep splits and consequently the total absence of membranes between gonal thickenings, as occurs in the range of variation between M. perforata ssp. mirabilis and M. chleuh Below, 1981.