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Meiourogonyaulax valensii
Meiourogonyaulax valensii Sarjeant, 1966
Originally (and now) Meiourogonyaulax, subsequently Lithodinia. This species is here retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83).
Gocht, 1976, transferred this species to Lithodinia Eisenack, 1935. Stover and Evitt, 1978, retained it in Meiourogonyaulax.
Dodekova, 1990, retained the species in Lithodinia.
Tax. sr. synonym of Lithodinia decapitata W. Wetzel, 1967, according to Fenton, 1981. Sarjeant, 1982, retained Lithodinia (as Meiourogonyaulax) decapitata as a separate species.
Holotype: Valensi, 1953, pl.2, figs.12-13 (as Gonyaulax sp.); Sarjeant, 1966, pl.15, fig.7, text-fig.37
Locus typicus: Arvault, Poitou, France
Stratum typicum: Bathonian
Translation Courtinat, 1989: LPP
Original description: Sarjeant, 1966, p.145-146
Diagnosis: A Meiourogonyaulax having a broadly ellipsoidal theca; lacking apex in all specimens seen. Tabulation ?4", 0a, 6"", 6c, 6""", 1p, 1p.v., 1"""". Crests of moderate height, slightly striated and irregularly perforate, with smooth or finely denticulate distal edges. Spines present at some crest nodes. Cingulum strongly spiral, relatively broad; sulcus broadening posteriorly, subdivided by low ridges. Shell surface punctate or alveolar.
Dimensions: Holotype: overall length 70 Ám, breadth 70 Ám; shell length, approx. 60 Ám, breadth approx. 50 Ám; width of transverse furrow c. 6 Ám.
Description: Although this species is based on Valensi"s (1953, Gonyaulax sp. indet.) single specimen, the author has also seen a number of specimens in material from the Bathonian of the Aquitaine Basin, unfortunately not available for description. From the angular profile of the apical archaeopyle, the former presence of at least four apical plates is deduced. The is no anterior intercalary plate. Six precingular plates are present, plate 1""" being reduced and elongate, separated from the antapex by a moderately large posterior intercalary plate. The antapex is occupied by a single large plate and is separated from the sulcus by a quadrate posterior ventral plate. The cingulum forms a strong laevorotatory spiral such that its two ends differ in antero-posterior position by over twice its width. It is clearly subdivided into six cingular plates. The sulcus is roughly wedge-shaped, broadening towards the posterior; it bears low ridges forming an irregular pattern. The shell surface is alveolar to punctate. The crests are moderately high, faintly striate and intermittently perforated; their distal edges are in part smooth, in part finely denticulate. Crest nodes are strengthened by stout spines in some or all cases. The crests bordering the sulcus are very reduced.
Remark:
Courtinat, 1989, p.178: Meiourogonyaulax cf. valensi and M. cf. pilla
M. cf. valensi possesses serrate crests but the septa are less well developed than in M. valensi. M. cf. pilla presents an autophragm without traces of paratabulation except for the paracingulum, whilst M. pilla is characterized by a faint paratabulation indicated by delicate ribs.
Affinities:
Sarjeant, 1966, p. 146
Meiourogonyaulax valensii is distinguished from the other species of this genus in the detail of tabulation and the nature of the crests.
Originally (and now) Meiourogonyaulax, subsequently Lithodinia. This species is here retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83).
Gocht, 1976, transferred this species to Lithodinia Eisenack, 1935. Stover and Evitt, 1978, retained it in Meiourogonyaulax.
Dodekova, 1990, retained the species in Lithodinia.
Tax. sr. synonym of Lithodinia decapitata W. Wetzel, 1967, according to Fenton, 1981. Sarjeant, 1982, retained Lithodinia (as Meiourogonyaulax) decapitata as a separate species.
Holotype: Valensi, 1953, pl.2, figs.12-13 (as Gonyaulax sp.); Sarjeant, 1966, pl.15, fig.7, text-fig.37
Locus typicus: Arvault, Poitou, France
Stratum typicum: Bathonian
Translation Courtinat, 1989: LPP
Original description: Sarjeant, 1966, p.145-146
Diagnosis: A Meiourogonyaulax having a broadly ellipsoidal theca; lacking apex in all specimens seen. Tabulation ?4", 0a, 6"", 6c, 6""", 1p, 1p.v., 1"""". Crests of moderate height, slightly striated and irregularly perforate, with smooth or finely denticulate distal edges. Spines present at some crest nodes. Cingulum strongly spiral, relatively broad; sulcus broadening posteriorly, subdivided by low ridges. Shell surface punctate or alveolar.
Dimensions: Holotype: overall length 70 Ám, breadth 70 Ám; shell length, approx. 60 Ám, breadth approx. 50 Ám; width of transverse furrow c. 6 Ám.
Description: Although this species is based on Valensi"s (1953, Gonyaulax sp. indet.) single specimen, the author has also seen a number of specimens in material from the Bathonian of the Aquitaine Basin, unfortunately not available for description. From the angular profile of the apical archaeopyle, the former presence of at least four apical plates is deduced. The is no anterior intercalary plate. Six precingular plates are present, plate 1""" being reduced and elongate, separated from the antapex by a moderately large posterior intercalary plate. The antapex is occupied by a single large plate and is separated from the sulcus by a quadrate posterior ventral plate. The cingulum forms a strong laevorotatory spiral such that its two ends differ in antero-posterior position by over twice its width. It is clearly subdivided into six cingular plates. The sulcus is roughly wedge-shaped, broadening towards the posterior; it bears low ridges forming an irregular pattern. The shell surface is alveolar to punctate. The crests are moderately high, faintly striate and intermittently perforated; their distal edges are in part smooth, in part finely denticulate. Crest nodes are strengthened by stout spines in some or all cases. The crests bordering the sulcus are very reduced.
Remark:
Courtinat, 1989, p.178: Meiourogonyaulax cf. valensi and M. cf. pilla
M. cf. valensi possesses serrate crests but the septa are less well developed than in M. valensi. M. cf. pilla presents an autophragm without traces of paratabulation except for the paracingulum, whilst M. pilla is characterized by a faint paratabulation indicated by delicate ribs.
Affinities:
Sarjeant, 1966, p. 146
Meiourogonyaulax valensii is distinguished from the other species of this genus in the detail of tabulation and the nature of the crests.