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Dinogymnium digitus
From Fensome et al., 2019:
Dinogymnium digitus (Deflandre, 1936b, p.166–167, pl.2, figs.4–5) Evitt et al., 1967, p.18–19. Holotype: Deflandre, 1935, textfigs. 7–8; Deflandre, 1936b, pl.2, figs.4–5. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. NIA. Age: Senonian.
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Original description: [Deflandre, 1936b] (translated from French):
GYMNODINIUM DIGITUS Deflandre.
PL. II, fig. 4, 5.
G. DEFLANDRE, Bulletin Biologique, LXIX, 1935, pp. 225 and 226, fig. 7, 8.
Holotype: AF 56, Silex S. 35, pebble, Paris.
The cell is somewhat spindle-shaped, with very rounded poles. The epitheca and hypotheca are of little difference in size. Since the transverse groove is circular, I arbitrarily consider the widest half-cell to be the epitheca; the longitudinal groove, difficult to see through (fig. 5), appears to extend almost equally on each side of the transverse groove. Both parts of the cell, epitheca and hypotheca, are similarly digitiform. The epitheca, which I believe to be somewhat distorted on the only specimen I possess, is slightly widened towards its middle, then tapers towards the apical pole, which is slightly ogival, but rounded. The hypothecus is cylindro-conical and the antapex is well rounded.
The membrane bears the marks of delicate striations, and fine punctuations arranged longitudinally are observed, especially on the hypothecus.
As can be seen in the figure, the specimen described is presented in oblique dorsal view. The length, rectified, is approximately 68 to 70 μm. According to the drawing, which is a projection made in camera lucida, it would be only 60 to 63 μm depending on the position of the flint flake. It appears that the cross-section is circular and that, consequently, the lateral view differs little from the frontal view. Gymnodinium digitus comes from a flint pebble (? Senonian) collected in Paris. It is not comparable to any current species.
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Comment: Evitt, Clarke and verdier 1967, p. 18-19
The species, as represented by Deflandre"s unique holotype in chert, is certainly different from other described species. The holotype is obliquely oriented in the chert chip so that it is difficult to gain a full appreciation of its proportions. Deflandre"s original figures are excellent and the specimen shows little more than his drawings. An archeopyle is not apparent. Coarse wall-canals are present in the cingulum and on both hypotract and epitract, but details of their orientation and distribution are obscure. The single specimen from Australia illustrated without description as Gymnodinium sp. by Eisenack (1959) and later under the name of this species (Eisenack, 196l) obviously shares with it some conspicuous features that distinguish both specimens from other described species. However, other undescribed species also exhibit these same features, differing from one another in details not accessible to observation in the holotype of D. digitus and not illustrated or mentioned by Eisenack. Until more material is known, the accuracy of Eisenack"s identification rests uncertain.
This species is also figured in (synonym list):
Gymnodinium digitus DEFLANDRE, Ig3sb, Bull. Biol. France Belgique, vol. 69,p.225-26, text-fig. 7-8 (nomen nudum; Senonian, France); DEFLANDRE, fig. 6h, Ann. Paleont, vol. 25, p. I66, ph I2, fig. 4-5 (first description, copies of original illustrations); DEFLANDRE, I952, Traite de Zoologie, text-fig. 3oIF (no text; copy of Deflandre, I935, fig. 7); [?] EISENACK, I961, Neues Jahrb. Geol. Palaont., Abh., vol. 112, ph 33, fig. 3 (figure only; Upper Cretaceous, Australia); EISENACK, 1964, Katalog der fossilen Dinoflagellaten, etc., vol. I, p. 429-30 (with copies of figures from Deflandre, I935); DEFLANDRE, 1966, Cahiers de Micropaleont., ser. 1, no. 2, p. 2-3 (no description or illustration). G. & M. DEFLANDRE, Fichier Micropaleont. Gen., ser. 15, card 292l (no text; copies of illustrations from Deflandre, 1935 and Ig36b, and new unnumbered photomicrograph of holotype), card 2922 (no text; copies of illustrations from Eisenack, I959 and 196l). Gymnodinium digitum Deflandre, DOWNIE & SARJEANT, I964 (I965), Geol. Soc. America, Mem. 94, p. II6 (bibl. ref. only; altered spelling of specific epithet is erroneous). [?] Gymnodinium sp. EISENACK, I959, Arch. Protistenkunde, vol. I04, pl. 3, fig. 2 (no description; first illustration of specimen refigured as G. digitus in Eisenack, I961, pl. 33, fig. 3; Upper Cretaceous, Australia).
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Comment (May, 1977):
Two specimens observed in the Mount Laurel Sand have somewhat expanded epitracts and elongate, but conical, and antapically rounded hypotracts. Although the Mount Laurel specimens lack costae on the epitract, Deflandre's (1935, page 225, text-figures 7-8) specimen apparently has faint longitudinal markings. The presence or absence of the markings on the epitract is likely a factor of intraspecific variability or lateral distorsion. Vozzhennikova (1967, plate V, figs. 5, 6, 12) illustrated epitracts devoid of longitudinal costae and others faint costae. The Mount Laurel specimens, as with Deflandre's (ibid.), have longitudinal costae on the hypotract. Surface ornamentation is faintly postulose. Archeopyle is apical and narrow and the operculum appears ventrally and dorsally attached.
Dimensions: Two specimens observed and measured: length 74-77 µm, width 25-28 µm. Epitract length: 34-37 µm, hypotract length: 40 µm.
Occurence: Mount Laurel Sand, extremely rare. Previously reported occurence: Senonian of France (Deflandre 1935), of Australia (Cookson and Eisenack), Upper Cretaceous of the Soviet Union (Vozzhennikova, 1967).
Dinogymnium digitus (Deflandre, 1936b, p.166–167, pl.2, figs.4–5) Evitt et al., 1967, p.18–19. Holotype: Deflandre, 1935, textfigs. 7–8; Deflandre, 1936b, pl.2, figs.4–5. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. NIA. Age: Senonian.
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Original description: [Deflandre, 1936b] (translated from French):
GYMNODINIUM DIGITUS Deflandre.
PL. II, fig. 4, 5.
G. DEFLANDRE, Bulletin Biologique, LXIX, 1935, pp. 225 and 226, fig. 7, 8.
Holotype: AF 56, Silex S. 35, pebble, Paris.
The cell is somewhat spindle-shaped, with very rounded poles. The epitheca and hypotheca are of little difference in size. Since the transverse groove is circular, I arbitrarily consider the widest half-cell to be the epitheca; the longitudinal groove, difficult to see through (fig. 5), appears to extend almost equally on each side of the transverse groove. Both parts of the cell, epitheca and hypotheca, are similarly digitiform. The epitheca, which I believe to be somewhat distorted on the only specimen I possess, is slightly widened towards its middle, then tapers towards the apical pole, which is slightly ogival, but rounded. The hypothecus is cylindro-conical and the antapex is well rounded.
The membrane bears the marks of delicate striations, and fine punctuations arranged longitudinally are observed, especially on the hypothecus.
As can be seen in the figure, the specimen described is presented in oblique dorsal view. The length, rectified, is approximately 68 to 70 μm. According to the drawing, which is a projection made in camera lucida, it would be only 60 to 63 μm depending on the position of the flint flake. It appears that the cross-section is circular and that, consequently, the lateral view differs little from the frontal view. Gymnodinium digitus comes from a flint pebble (? Senonian) collected in Paris. It is not comparable to any current species.
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Comment: Evitt, Clarke and verdier 1967, p. 18-19
The species, as represented by Deflandre"s unique holotype in chert, is certainly different from other described species. The holotype is obliquely oriented in the chert chip so that it is difficult to gain a full appreciation of its proportions. Deflandre"s original figures are excellent and the specimen shows little more than his drawings. An archeopyle is not apparent. Coarse wall-canals are present in the cingulum and on both hypotract and epitract, but details of their orientation and distribution are obscure. The single specimen from Australia illustrated without description as Gymnodinium sp. by Eisenack (1959) and later under the name of this species (Eisenack, 196l) obviously shares with it some conspicuous features that distinguish both specimens from other described species. However, other undescribed species also exhibit these same features, differing from one another in details not accessible to observation in the holotype of D. digitus and not illustrated or mentioned by Eisenack. Until more material is known, the accuracy of Eisenack"s identification rests uncertain.
This species is also figured in (synonym list):
Gymnodinium digitus DEFLANDRE, Ig3sb, Bull. Biol. France Belgique, vol. 69,p.225-26, text-fig. 7-8 (nomen nudum; Senonian, France); DEFLANDRE, fig. 6h, Ann. Paleont, vol. 25, p. I66, ph I2, fig. 4-5 (first description, copies of original illustrations); DEFLANDRE, I952, Traite de Zoologie, text-fig. 3oIF (no text; copy of Deflandre, I935, fig. 7); [?] EISENACK, I961, Neues Jahrb. Geol. Palaont., Abh., vol. 112, ph 33, fig. 3 (figure only; Upper Cretaceous, Australia); EISENACK, 1964, Katalog der fossilen Dinoflagellaten, etc., vol. I, p. 429-30 (with copies of figures from Deflandre, I935); DEFLANDRE, 1966, Cahiers de Micropaleont., ser. 1, no. 2, p. 2-3 (no description or illustration). G. & M. DEFLANDRE, Fichier Micropaleont. Gen., ser. 15, card 292l (no text; copies of illustrations from Deflandre, 1935 and Ig36b, and new unnumbered photomicrograph of holotype), card 2922 (no text; copies of illustrations from Eisenack, I959 and 196l). Gymnodinium digitum Deflandre, DOWNIE & SARJEANT, I964 (I965), Geol. Soc. America, Mem. 94, p. II6 (bibl. ref. only; altered spelling of specific epithet is erroneous). [?] Gymnodinium sp. EISENACK, I959, Arch. Protistenkunde, vol. I04, pl. 3, fig. 2 (no description; first illustration of specimen refigured as G. digitus in Eisenack, I961, pl. 33, fig. 3; Upper Cretaceous, Australia).
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Comment (May, 1977):
Two specimens observed in the Mount Laurel Sand have somewhat expanded epitracts and elongate, but conical, and antapically rounded hypotracts. Although the Mount Laurel specimens lack costae on the epitract, Deflandre's (1935, page 225, text-figures 7-8) specimen apparently has faint longitudinal markings. The presence or absence of the markings on the epitract is likely a factor of intraspecific variability or lateral distorsion. Vozzhennikova (1967, plate V, figs. 5, 6, 12) illustrated epitracts devoid of longitudinal costae and others faint costae. The Mount Laurel specimens, as with Deflandre's (ibid.), have longitudinal costae on the hypotract. Surface ornamentation is faintly postulose. Archeopyle is apical and narrow and the operculum appears ventrally and dorsally attached.
Dimensions: Two specimens observed and measured: length 74-77 µm, width 25-28 µm. Epitract length: 34-37 µm, hypotract length: 40 µm.
Occurence: Mount Laurel Sand, extremely rare. Previously reported occurence: Senonian of France (Deflandre 1935), of Australia (Cookson and Eisenack), Upper Cretaceous of the Soviet Union (Vozzhennikova, 1967).