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Laciniadinium williamsii
Laciniadinium williamsii Ioannides, 1986
Holotype: Ioannides, 1986, pl.10, fig.1
Age: Santonian-Campanian
Original description (Ioannides, 1986):
Laciniadinium williamsii sp. nov.
Plate 10, figures 1-6; Plate 11, figure 5
Material. Holotype. Plate 10, figure I, GSC 65215, slide P2047-23D, 20.3 x 125.0; GSC locality C-60129; Kanguk Formation, Section 77-HFA-46A, South Coast section, Bylot Island, District of Franklin; Santonian-Carnpanian. Pericyst length, 49 µm, pericyst width, 35 µm.
Derivation of name. In honour of G.L. Williams, Geological Survey of Canada.
Diagnosis. Shape of cyst compressed subspherical to convexly biconical. Apical and antapical horns short. Autophragm smooth to finely ornamented. Archeopyle combination, type tI3Pa. Detachment of operculum from 3' marked by an angular concavity of operculum along the original contact.
Description. Cyst proximate; shape compressed subspherical to convexly biconical; apical, and probably a left antapical, horn present; right (?) antapical horn absent or, rarely, slightly developed. Apical horn short, parallel-sided to almost truncated conical, sometimes topped with two or more minute papillae. Left (?) antapical horn short, hollow, acuminate. Wall consists of autophragm only, except a t apex and antapex where two layers may be present. No parasutural features observed, although some folds may simulate some plate boundaries. Autophragm smooth to minutely ornamented with grana and/or small spines, about 1 pm high. Paratabulation indicated by archeopyle and paracingulum only. Archeopyle combination, type tI3Pa, involves parapIates la to 3a and 3" to 5"; operculum flap-like, simple, and attached antapically along paracingulum. Detachment from 3' marked by angular concavity of operculum along original contact. Paracingulum indicated by low transverse parallel ridges or folds. Parasulcus delimited by low ridges or attenuated folds, which extend two thirds onto both epicyst and hypocyst.
Dimensions. Cyst length 39-54 µm, with 31-43 µm; apical horn 2-6 µm high, 2-4 µm wide; antapical horn 2-7 µm high; cingulum about 4 µm wide; autophragm 1 µm or less in thickness (24 specimens measured).
Comparison. Laciniadinium orbiculatum McIntyre, 1975 is larger (70-100 µm long), has no visible antapical horns and is oval to spherical in shape. Laciniadinium biconiculum McIntyre, 1975 is larger (55-85 µm long), is more distinctly biconical and has a rather prominent, striated ornamentation.
Holotype: Ioannides, 1986, pl.10, fig.1
Age: Santonian-Campanian
Original description (Ioannides, 1986):
Laciniadinium williamsii sp. nov.
Plate 10, figures 1-6; Plate 11, figure 5
Material. Holotype. Plate 10, figure I, GSC 65215, slide P2047-23D, 20.3 x 125.0; GSC locality C-60129; Kanguk Formation, Section 77-HFA-46A, South Coast section, Bylot Island, District of Franklin; Santonian-Carnpanian. Pericyst length, 49 µm, pericyst width, 35 µm.
Derivation of name. In honour of G.L. Williams, Geological Survey of Canada.
Diagnosis. Shape of cyst compressed subspherical to convexly biconical. Apical and antapical horns short. Autophragm smooth to finely ornamented. Archeopyle combination, type tI3Pa. Detachment of operculum from 3' marked by an angular concavity of operculum along the original contact.
Description. Cyst proximate; shape compressed subspherical to convexly biconical; apical, and probably a left antapical, horn present; right (?) antapical horn absent or, rarely, slightly developed. Apical horn short, parallel-sided to almost truncated conical, sometimes topped with two or more minute papillae. Left (?) antapical horn short, hollow, acuminate. Wall consists of autophragm only, except a t apex and antapex where two layers may be present. No parasutural features observed, although some folds may simulate some plate boundaries. Autophragm smooth to minutely ornamented with grana and/or small spines, about 1 pm high. Paratabulation indicated by archeopyle and paracingulum only. Archeopyle combination, type tI3Pa, involves parapIates la to 3a and 3" to 5"; operculum flap-like, simple, and attached antapically along paracingulum. Detachment from 3' marked by angular concavity of operculum along original contact. Paracingulum indicated by low transverse parallel ridges or folds. Parasulcus delimited by low ridges or attenuated folds, which extend two thirds onto both epicyst and hypocyst.
Dimensions. Cyst length 39-54 µm, with 31-43 µm; apical horn 2-6 µm high, 2-4 µm wide; antapical horn 2-7 µm high; cingulum about 4 µm wide; autophragm 1 µm or less in thickness (24 specimens measured).
Comparison. Laciniadinium orbiculatum McIntyre, 1975 is larger (70-100 µm long), has no visible antapical horns and is oval to spherical in shape. Laciniadinium biconiculum McIntyre, 1975 is larger (55-85 µm long), is more distinctly biconical and has a rather prominent, striated ornamentation.