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Meiourogonyaulax rioultii
Meiourogonyaulax rioultii Sarjeant, 1965, p.181, pl.1, fig.1; text-fig.1 ex Sarjeant, 1968, p.229.
Originally Meiourogonyaulax, subsequently Lithodinia, thirdly (and now) Meiourogonyaulax?, fourthly Lithodinia?. This species is here retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83).
Questionable assignment: Stover and Evitt (1978, p.63) as a problematic species.
This name was not validly published in Sarjeant (1965, p.181) since the genus Meiourogonyaulax was not validly published until 1966.
Gocht, 1976, transferred this species to Lithodinia Eisenack, 1935. Stover and Evitt, 1978, retained it in Meiourogonyaulax, and considered it to be a problematical species of Meiourogonyaulax. Williams et al., 1993, questionably retained the species in Lithodinia.
Holotype: Sarjeant, 1965, pl.1, fig.1
Age: Early Callovian
Original Diagnosis. Sarjeant 1965, p. 181: Meiourogonyaulax rioulti
A species of Meiourogonyaulax having an ovoidal shell with the tabulation ?", la, 6", 6c, 6"", 1-? 2 p, 1 pv, 1"". The apex is lost in archaeopyle formation. The reflected tabulation is outlined generally by low ridges, with bifurcate processes arising principally, but not constantly, at no lles; however, the antapex is surrounded by high, delicate crests. The shell wall is very thin and delicate; its surface lacks ornament. The cingulum is broad and strongly laevo-rotatory: the sulcus is likewise broad and has only a short hypotractal portion.
Dimensions. Holotype: overall length 44µ, breadth 13µ, shell length 41.5µ, breadth 40µ. Observed range of dimensions: overall length 50µ, overall breadth 40-46µ. (Apices lacking in all cases.)
Discussion. Sarjeant 1965, p. 181
This is a small species with an unusually thin and delicate shell wall; only four specimens were recorded, but damaged specimens would readily escape recognition. In all cases, the shell was damaged and folded. The holotype affords an excellent picture of the ventral tabulation, but the dorsal tabulation is only tentative. In particular, the presence of the second posterior intercalary plate must be considered doubtful; a
similar plate is not known in any other species of the genus.
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Sarjeant 1968, p.229-230
Meiourogonyaulax rioulti Sarjeant 1968
Meiourogonyalllax rioulti Sarjeant, 1965, p. 181, pl. 1, fig. 1, text-fig. 1, nom. nud.
Remarks: As a result of the publication of two papers in inverse order, this species was described ahead of the valid publication of the generic name and was thereford technically invalid (Art. 43, I.C.B.N.). It is therefore here validated.
Originally Meiourogonyaulax, subsequently Lithodinia, thirdly (and now) Meiourogonyaulax?, fourthly Lithodinia?. This species is here retained in Meiourogonyaulax following the retention of the genus by Riding and Helby (2001d, p.81,83).
Questionable assignment: Stover and Evitt (1978, p.63) as a problematic species.
This name was not validly published in Sarjeant (1965, p.181) since the genus Meiourogonyaulax was not validly published until 1966.
Gocht, 1976, transferred this species to Lithodinia Eisenack, 1935. Stover and Evitt, 1978, retained it in Meiourogonyaulax, and considered it to be a problematical species of Meiourogonyaulax. Williams et al., 1993, questionably retained the species in Lithodinia.
Holotype: Sarjeant, 1965, pl.1, fig.1
Age: Early Callovian
Original Diagnosis. Sarjeant 1965, p. 181: Meiourogonyaulax rioulti
A species of Meiourogonyaulax having an ovoidal shell with the tabulation ?", la, 6", 6c, 6"", 1-? 2 p, 1 pv, 1"". The apex is lost in archaeopyle formation. The reflected tabulation is outlined generally by low ridges, with bifurcate processes arising principally, but not constantly, at no lles; however, the antapex is surrounded by high, delicate crests. The shell wall is very thin and delicate; its surface lacks ornament. The cingulum is broad and strongly laevo-rotatory: the sulcus is likewise broad and has only a short hypotractal portion.
Dimensions. Holotype: overall length 44µ, breadth 13µ, shell length 41.5µ, breadth 40µ. Observed range of dimensions: overall length 50µ, overall breadth 40-46µ. (Apices lacking in all cases.)
Discussion. Sarjeant 1965, p. 181
This is a small species with an unusually thin and delicate shell wall; only four specimens were recorded, but damaged specimens would readily escape recognition. In all cases, the shell was damaged and folded. The holotype affords an excellent picture of the ventral tabulation, but the dorsal tabulation is only tentative. In particular, the presence of the second posterior intercalary plate must be considered doubtful; a
similar plate is not known in any other species of the genus.
----------------------------------------------------------------------------------------------------------------
Sarjeant 1968, p.229-230
Meiourogonyaulax rioulti Sarjeant 1968
Meiourogonyalllax rioulti Sarjeant, 1965, p. 181, pl. 1, fig. 1, text-fig. 1, nom. nud.
Remarks: As a result of the publication of two papers in inverse order, this species was described ahead of the valid publication of the generic name and was thereford technically invalid (Art. 43, I.C.B.N.). It is therefore here validated.