Back
Lopsidinium paxense
Lopsidinium paxense Dolby, 2014, p.176, pl.1, figs.9–12.
Holotype: Dolby, 2014, pl.1, fig. 10.
Age: middle Albian.
Original description (Dolby, 2014):
Lopsidinium paxense sp. nov. Plate 1, figures 9–12
Holotype. Plate 1, figure 10; England Finder G35/3.
Type locality. Peace River Section #3, Alberta (Hathway et al. in press) sample AGS5552, 2 m above the base of the section, Loon River Formation.
Repository. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A 0E8, under curation number 136244.
Diagnosis. A species of Lopsidinium with predominantly narrow, cylindrical processes confined to the apical and antapical areas and as longitudinal ventral/ sulcal and dorsal series. The 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 processes. Tabulation: Indicated only by archaeopyle sutures and a sulcal notch. Archaeopyle: Apical; operculum mostly attached or partially detached in approximately 85% of the observed specimens. Body surface: Smooth to finely granulose. Wall features: Processes mostly hollow, cylindrical to very slightly tapering, distally-flared (trumpet-shaped) with smooth distal margins. The flaring is usually very close to the distal margin. Broad-based and strongly tapering (sub-conical) antapical processes with longitudinal wrinkling are very rare.
Distribution of processes Apical: 5–9, cylindrical. Antapical: 6–11, mostly cylindrical. Ventral/sulcal: 2–6, cylindrical. Dorsal: 1–4, cylindrical.
Dimensions [Min (Mode) Max]
Length, complete specimens: 34 (41) 49 µm (21 specimens).
Width: 18 (21) 24 µm (25 specimens).
Process length: 6 (12) 16 µm.
Process diameter: 1–3 µm (cylindrical).
Tapered, base maximum: 6–7.5 µm (rare).
Flare diameter: 3–7 µm.
Derivation of name. From the Latin pax meaning ‘peace’, in reference to the type locality by the Peace River, Alberta.
Comparison. Lopsidinium subrisum lacks dorsal processes. The broad-based, strongly tapering processes that are characteristic of L. subrisum are very rare in L. paxense and are confined to the antapex. The processes in Tanyosphaeridium salpinx Norvick 1976 resemble the cylindrical processes in L. paxense but they are distributed over the entire body.
Occurrence. Middle Albian, upper Loon River Formation, Peace River Sections 1 and 3, northwestern Alberta.
Holotype: Dolby, 2014, pl.1, fig. 10.
Age: middle Albian.
Original description (Dolby, 2014):
Lopsidinium paxense sp. nov. Plate 1, figures 9–12
Holotype. Plate 1, figure 10; England Finder G35/3.
Type locality. Peace River Section #3, Alberta (Hathway et al. in press) sample AGS5552, 2 m above the base of the section, Loon River Formation.
Repository. Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario, K1A 0E8, under curation number 136244.
Diagnosis. A species of Lopsidinium with predominantly narrow, cylindrical processes confined to the apical and antapical areas and as longitudinal ventral/ sulcal and dorsal series. The 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 processes. Tabulation: Indicated only by archaeopyle sutures and a sulcal notch. Archaeopyle: Apical; operculum mostly attached or partially detached in approximately 85% of the observed specimens. Body surface: Smooth to finely granulose. Wall features: Processes mostly hollow, cylindrical to very slightly tapering, distally-flared (trumpet-shaped) with smooth distal margins. The flaring is usually very close to the distal margin. Broad-based and strongly tapering (sub-conical) antapical processes with longitudinal wrinkling are very rare.
Distribution of processes Apical: 5–9, cylindrical. Antapical: 6–11, mostly cylindrical. Ventral/sulcal: 2–6, cylindrical. Dorsal: 1–4, cylindrical.
Dimensions [Min (Mode) Max]
Length, complete specimens: 34 (41) 49 µm (21 specimens).
Width: 18 (21) 24 µm (25 specimens).
Process length: 6 (12) 16 µm.
Process diameter: 1–3 µm (cylindrical).
Tapered, base maximum: 6–7.5 µm (rare).
Flare diameter: 3–7 µm.
Derivation of name. From the Latin pax meaning ‘peace’, in reference to the type locality by the Peace River, Alberta.
Comparison. Lopsidinium subrisum lacks dorsal processes. The broad-based, strongly tapering processes that are characteristic of L. subrisum are very rare in L. paxense and are confined to the antapex. The processes in Tanyosphaeridium salpinx Norvick 1976 resemble the cylindrical processes in L. paxense but they are distributed over the entire body.
Occurrence. Middle Albian, upper Loon River Formation, Peace River Sections 1 and 3, northwestern Alberta.