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Canninginopsis monile
From Fensome et al., 2019:
(Duxbury, 2002, p.78, pl.1, figs.7–8,10–12) Fensome et al., 2019a, p.33.
Holotype: Duxbury, 2002, pl.1, figs.7–8; Fensome et al., 2019a, figs.14G–H.
Originally Cerbia, subsequently (and now) Canninginopsis.
Since Duxbury expressly derived the specific epithet from the Latin noun "monile" (necklace), it should be cited as monile, not monilis. NIA.
Age: late Aptian–early Albian.
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Original description Duxbury, 2002:
Derivation. From the Latin monile, necklace – in reference to the parasutural ornament of this species.
Diagnosis. A thin-walled, proximate dinoflagellate cyst with an angular outline. A pronounced, rounded apical horn and low lateral and antapical projections are present. Short spines are aligned very largely along epicystal and hypocystal parasutures, although occasionally these also may occur along paracingular margins. These spines are variable in their morphology, often distally bifurcate and sometimes laterally joined at their distal extremes. Spines at the apex anastomose into a fibrous network. Paratabulation appears to be typical for the genus. The archaeopyle is apical, with a zig-zag margin; the operculum is almost always detached.
Holotype. Plate 1, figs 7, 8.
Paratype. Plate 1, fig. 12.
Locality & horizon. Holotype: well 13/30a-4 at 6387.00 ft (conventional core), Early Albian (E.F. W37.0). Paratype: well
20/4b-7 at 8660.20 ft (conventional core), Late Aptian (E.F. N40.0).
Dimensions. Holotype (operculum detached): length 83 μm, width 85 μm. Overall (operculum detached): length 95 (80)
67.5 μm; width 90 (77.5) 67.5 μm; 30 specimens measured. Paratype (operculum attached): length 105 μm, width 80 μm. Remarks. Cerbia monilis n. sp. differs from all other species of this genus in its very distinct cyst morphology, particularly an angularity of outline caused by the presence of apical, lateral and antapical projections, and the characteristic cyst folding. The latter feature is almost exclusively restricted to parasutural areas, so that parasutural spines typically run along the folds. Folding imparts an essentially triangular shape to the hypocyst, causes some constriction of the archaeopyle and emphasizes the height of the dorsal epicyst. In addition, although some dorso-ventral flattening is observed, it appears to be significantly less pronounced than in other species of this genus. The operculum is almost always detached, and only one specimen with an attached (but displaced) operculum was observed in the study wells (paratype, Pl.1, fig. 12). This very distinctive species is very short-ranging, restricted to the Aptian/Albian boundary interval, zones LKP31 and LKP32 of Duxbury (2001) (jacobi to tardefurcata ammonite zones), where it can be common. In the study area, its inception is within the Wick Sandstone Formation, Captain Sandstone
Member and Upper Britannia Sandstone Formation, and its extinction is within the Carrack Formation.
(Duxbury, 2002, p.78, pl.1, figs.7–8,10–12) Fensome et al., 2019a, p.33.
Holotype: Duxbury, 2002, pl.1, figs.7–8; Fensome et al., 2019a, figs.14G–H.
Originally Cerbia, subsequently (and now) Canninginopsis.
Since Duxbury expressly derived the specific epithet from the Latin noun "monile" (necklace), it should be cited as monile, not monilis. NIA.
Age: late Aptian–early Albian.
---------------------------------------------------------------------------------------------------
Original description Duxbury, 2002:
Derivation. From the Latin monile, necklace – in reference to the parasutural ornament of this species.
Diagnosis. A thin-walled, proximate dinoflagellate cyst with an angular outline. A pronounced, rounded apical horn and low lateral and antapical projections are present. Short spines are aligned very largely along epicystal and hypocystal parasutures, although occasionally these also may occur along paracingular margins. These spines are variable in their morphology, often distally bifurcate and sometimes laterally joined at their distal extremes. Spines at the apex anastomose into a fibrous network. Paratabulation appears to be typical for the genus. The archaeopyle is apical, with a zig-zag margin; the operculum is almost always detached.
Holotype. Plate 1, figs 7, 8.
Paratype. Plate 1, fig. 12.
Locality & horizon. Holotype: well 13/30a-4 at 6387.00 ft (conventional core), Early Albian (E.F. W37.0). Paratype: well
20/4b-7 at 8660.20 ft (conventional core), Late Aptian (E.F. N40.0).
Dimensions. Holotype (operculum detached): length 83 μm, width 85 μm. Overall (operculum detached): length 95 (80)
67.5 μm; width 90 (77.5) 67.5 μm; 30 specimens measured. Paratype (operculum attached): length 105 μm, width 80 μm. Remarks. Cerbia monilis n. sp. differs from all other species of this genus in its very distinct cyst morphology, particularly an angularity of outline caused by the presence of apical, lateral and antapical projections, and the characteristic cyst folding. The latter feature is almost exclusively restricted to parasutural areas, so that parasutural spines typically run along the folds. Folding imparts an essentially triangular shape to the hypocyst, causes some constriction of the archaeopyle and emphasizes the height of the dorsal epicyst. In addition, although some dorso-ventral flattening is observed, it appears to be significantly less pronounced than in other species of this genus. The operculum is almost always detached, and only one specimen with an attached (but displaced) operculum was observed in the study wells (paratype, Pl.1, fig. 12). This very distinctive species is very short-ranging, restricted to the Aptian/Albian boundary interval, zones LKP31 and LKP32 of Duxbury (2001) (jacobi to tardefurcata ammonite zones), where it can be common. In the study area, its inception is within the Wick Sandstone Formation, Captain Sandstone
Member and Upper Britannia Sandstone Formation, and its extinction is within the Carrack Formation.