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Lopsidinium subrisum
Lopsidinium subrisum Dolby, 2014, p.173,175–176, pl.1, figs.1–8.
Holotype: Dolby, 2014, pl.1, fig.2.
Age: early Albian.
Original description (Dolby, 2014):
Lopsidinium subrisum sp. nov. Plate 1, figures 1–8
Holotype. Plate 1, figure 2; England Finder N22;
Type locality. CNRL et al. Primrose 100/7-14-67- 3W4, Alberta, 503.2 m, Clearwater Formation.
Repository. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A 0E8 under curation number 136243.
Diagnosis. A species of Lopsidinium with a mixture of tapering broad-based, and cylindrical processes con- fined to the apical and antapical areas and as a longitudinal sulcal series. The dorsal and lateral surfaces are devoid of processes.
Description. Shape: The cyst body is elongate and ellipsoidal. Wall relationships: The cyst is acavate. The periphragm and endophragm are closely appressed except where the periphragm forms the processes. Tabulation: Indicated only by archaeopyle sutures and a sulcal notch. Archaeopyle: Apical; operculum often absent but attached or partially detached in approximately 35% of the observed specimens. Body surface: Smooth to finely granulose. Wall features: Of two principal types: (1) Hollow, cylindrical, distally-flared (trumpetshaped) with smooth, slightly thickened distal margins. The flaring is most often very close to the distal margin but in some cases it begins much lower down (around three-fifths of the process length from the base) resulting in a goblet shape. (2) Broad-based, often strongly tapering for 60– 90% of the process length before flaring. Longitudinal wrinkles are usually present. The bases appear to be elliptical in cross section with a very small minor axis that is of similar size to the diameter of the smaller cylindrical elements. Those in the sulcal area often appear to be flattened at the proximal end.
Distribution of processes Apical: 4–8, mostly cylindrical. Antapical: 4–18, mostly cylindrical. Ventral/sulcal: 1–5. Both cylindrical and tapering. Dorsal: Absent.
Dimensions [Min (Mode) Max]
Length, complete specimens: 32 (44) 50 µm (11 specimens).
Length, excluding operculum: 30 (37) 46 µm (30 specimens).
Width: 16 (20) 26 µm (37 specimens).
Process length: 8 (13) 18 µm.
Process diameter: 2–4 µm (cylindrical).
Tapered, base maximum: 7—24 µm.
Flare diameter: 4–18 µm.
Derivation of name. From the Latin subrisum meaning ‘smiled’, the response of most palynologists when shown this species for the first time.
Discussion. Some of the apical and antapical processes may be large and parallel-sided or flare from the base. The geometry of the large tapering processes is intriguing. The oval cross section of the base with a very small minor axis and very large major axis appears to be the result of the fusion of several smaller elements.
Occurrence. Lower Albian, lower Clearwater Formation, Cold Lake and Fort McMurray Oil Sands areas, northeastern Alberta.
Holotype: Dolby, 2014, pl.1, fig.2.
Age: early Albian.
Original description (Dolby, 2014):
Lopsidinium subrisum sp. nov. Plate 1, figures 1–8
Holotype. Plate 1, figure 2; England Finder N22;
Type locality. CNRL et al. Primrose 100/7-14-67- 3W4, Alberta, 503.2 m, Clearwater Formation.
Repository. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A 0E8 under curation number 136243.
Diagnosis. A species of Lopsidinium with a mixture of tapering broad-based, and cylindrical processes con- fined to the apical and antapical areas and as a longitudinal sulcal series. The dorsal and lateral surfaces are devoid of processes.
Description. Shape: The cyst body is elongate and ellipsoidal. Wall relationships: The cyst is acavate. The periphragm and endophragm are closely appressed except where the periphragm forms the processes. Tabulation: Indicated only by archaeopyle sutures and a sulcal notch. Archaeopyle: Apical; operculum often absent but attached or partially detached in approximately 35% of the observed specimens. Body surface: Smooth to finely granulose. Wall features: Of two principal types: (1) Hollow, cylindrical, distally-flared (trumpetshaped) with smooth, slightly thickened distal margins. The flaring is most often very close to the distal margin but in some cases it begins much lower down (around three-fifths of the process length from the base) resulting in a goblet shape. (2) Broad-based, often strongly tapering for 60– 90% of the process length before flaring. Longitudinal wrinkles are usually present. The bases appear to be elliptical in cross section with a very small minor axis that is of similar size to the diameter of the smaller cylindrical elements. Those in the sulcal area often appear to be flattened at the proximal end.
Distribution of processes Apical: 4–8, mostly cylindrical. Antapical: 4–18, mostly cylindrical. Ventral/sulcal: 1–5. Both cylindrical and tapering. Dorsal: Absent.
Dimensions [Min (Mode) Max]
Length, complete specimens: 32 (44) 50 µm (11 specimens).
Length, excluding operculum: 30 (37) 46 µm (30 specimens).
Width: 16 (20) 26 µm (37 specimens).
Process length: 8 (13) 18 µm.
Process diameter: 2–4 µm (cylindrical).
Tapered, base maximum: 7—24 µm.
Flare diameter: 4–18 µm.
Derivation of name. From the Latin subrisum meaning ‘smiled’, the response of most palynologists when shown this species for the first time.
Discussion. Some of the apical and antapical processes may be large and parallel-sided or flare from the base. The geometry of the large tapering processes is intriguing. The oval cross section of the base with a very small minor axis and very large major axis appears to be the result of the fusion of several smaller elements.
Occurrence. Lower Albian, lower Clearwater Formation, Cold Lake and Fort McMurray Oil Sands areas, northeastern Alberta.