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Tenua reducta
From Fensome et al., 2019:
Tenua reducta (Châteauneuf, 1980, p.136, pl.21, fig.10) Courtinat in Fauconnier and Masure, 2004, p.557.
Holotype: Châteauneuf, 1980, pl.21, fig.10; Fauconnier and Masure, 2004, pl.18, figs.11–15; Fensome et al., 2019a, fig.18K.
Originally Cyclonephelium, subsequently (and now) Tenua Eisenack.
Age: Late Eocene (Marinesian–Ludian).
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Original decription (Châteauneuf, 1980): Translation PKB 2024
Cyclonephelium reductum n.sp. (Pl. 1493)
Origin of the name: from the nature of the appendages
Holotype: Chelles survey, Sc. 4, slide 9218, coordinates: 41.2/121/10
Type locality: Chelles, St. Ouen Limestone, Marinesian, Paris Basin
Diagnosis: Lenticular cyst with asymmetrical antapical protuberance. Cut apical margin, dorsal-ventral flattening and medial constriction of the cyst. Cyst wall made up of a thin layer or autophragm. Sutural characters not discernible. There is no process in this type of cingulate alignment. The tabulation is expressed only by the zig-zag division of the margin of the archeopyle. Apical archaeopyle with free operculum. Dense ornamentation, composed only of spines of very variable length, with a less widened base and an unordered arrangement on the surface of the cyst. Reduction of ornamentation in the mid-ventral and dorsal areas. The autophagm is decorated between the thorns.
Dimensions de l’holotype : Hauteur 60 µm, largeur 70 µm, dimensions des épines : 2 à 5 µm – variations de taille kyste : 55-65 µm/60-70 µm, épines : 1 à 7 µm.
Stratigraphy: Marinesian to Lundien (common)
Note: this species characterizes highly desalinated deposits in the Paris Basin. It is part of quasi-monospecific groups and can reach high values, particularly in the St. Ouen Limestone.
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Comments Fensome et al., 2019a:
Châteauneuf (1980, p. 136) provided the following diagnosis for this species:
"[Cyst] lenticular and antapical protuberances bisymmetrical. Apical margin truncated, dorso-ventral flattening and median constriction of the cyst. Cyst surface composed of one thin layer or autophragm. Sutural features not discernible. In this type [species?] there is no cingular alignment of processes. Tabulation is expressed only by the truncated zigzag margin of the archaeopyle. Archaeopyle apical, with free operculum. Ornamentation dense, composed uniquely of spines of very variable length, with more or less expanded bases, with no ordered arrangement over the cyst surface. Ornamentation reduced in median dorso-ventral zones. The autophragm is ornamented between spines. …. [Translation]"
The features of this species are not clearly shown on the single illustration that Châteauneuf (1980) provided. However they are clearer in the re-illustrations of the holotype in Fauconnier and Masure (2004, pl. 18, figs 11–15). These show the presence of short spines; the ventral surface may be devoid of spines in its centralmost area, but across the dorsal surface are sparse spines in a penitabular and nontabular arrangement. Châteauneuf (1980) did not mention the nature of the distal process endings and they are unclear in the original illustration; from the re-illustrations they appear to me mostly acuminate or slightly bulbous. This is an unusual morphology for Eocene areoligeraceans.
Stratigraphical occurrence. Châteauneuf (1980) recovered this species from the Upper Eocene of France.
Tenua reducta (Châteauneuf, 1980, p.136, pl.21, fig.10) Courtinat in Fauconnier and Masure, 2004, p.557.
Holotype: Châteauneuf, 1980, pl.21, fig.10; Fauconnier and Masure, 2004, pl.18, figs.11–15; Fensome et al., 2019a, fig.18K.
Originally Cyclonephelium, subsequently (and now) Tenua Eisenack.
Age: Late Eocene (Marinesian–Ludian).
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Original decription (Châteauneuf, 1980): Translation PKB 2024
Cyclonephelium reductum n.sp. (Pl. 1493)
Origin of the name: from the nature of the appendages
Holotype: Chelles survey, Sc. 4, slide 9218, coordinates: 41.2/121/10
Type locality: Chelles, St. Ouen Limestone, Marinesian, Paris Basin
Diagnosis: Lenticular cyst with asymmetrical antapical protuberance. Cut apical margin, dorsal-ventral flattening and medial constriction of the cyst. Cyst wall made up of a thin layer or autophragm. Sutural characters not discernible. There is no process in this type of cingulate alignment. The tabulation is expressed only by the zig-zag division of the margin of the archeopyle. Apical archaeopyle with free operculum. Dense ornamentation, composed only of spines of very variable length, with a less widened base and an unordered arrangement on the surface of the cyst. Reduction of ornamentation in the mid-ventral and dorsal areas. The autophagm is decorated between the thorns.
Dimensions de l’holotype : Hauteur 60 µm, largeur 70 µm, dimensions des épines : 2 à 5 µm – variations de taille kyste : 55-65 µm/60-70 µm, épines : 1 à 7 µm.
Stratigraphy: Marinesian to Lundien (common)
Note: this species characterizes highly desalinated deposits in the Paris Basin. It is part of quasi-monospecific groups and can reach high values, particularly in the St. Ouen Limestone.
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Comments Fensome et al., 2019a:
Châteauneuf (1980, p. 136) provided the following diagnosis for this species:
"[Cyst] lenticular and antapical protuberances bisymmetrical. Apical margin truncated, dorso-ventral flattening and median constriction of the cyst. Cyst surface composed of one thin layer or autophragm. Sutural features not discernible. In this type [species?] there is no cingular alignment of processes. Tabulation is expressed only by the truncated zigzag margin of the archaeopyle. Archaeopyle apical, with free operculum. Ornamentation dense, composed uniquely of spines of very variable length, with more or less expanded bases, with no ordered arrangement over the cyst surface. Ornamentation reduced in median dorso-ventral zones. The autophragm is ornamented between spines. …. [Translation]"
The features of this species are not clearly shown on the single illustration that Châteauneuf (1980) provided. However they are clearer in the re-illustrations of the holotype in Fauconnier and Masure (2004, pl. 18, figs 11–15). These show the presence of short spines; the ventral surface may be devoid of spines in its centralmost area, but across the dorsal surface are sparse spines in a penitabular and nontabular arrangement. Châteauneuf (1980) did not mention the nature of the distal process endings and they are unclear in the original illustration; from the re-illustrations they appear to me mostly acuminate or slightly bulbous. This is an unusual morphology for Eocene areoligeraceans.
Stratigraphical occurrence. Châteauneuf (1980) recovered this species from the Upper Eocene of France.