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Ascodinium waltonii
Ascodinium waltonii, (Pocock, 1972), Helenes, 1983
NOW Ovoidinium. Originally Evittia (generic name illegitimate), subsequently Pocockia, thirdly (and now) Ovoidinium, fourthly Ascodinium. Lentin and Williams (1989, p.270) retained this species in Ovoidinium.
Holotype: Pocock, 1972, pl.22, fig.14
Locus typicus: Tidewater Davidson Crown, Western Canada
Stratum typicum: ?Toarcian-?Bajocian
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Original description as Evittia waltonii: [Pocock, 1972, p. 93]:
Description:
Vesicle somewhat flattened dorso-ventrally; capsule ovoid to sub-spherical; scabrate; 1.0-1.5 µm thick; enveloped by a thin outer wall that is appressed to the capsule equatorially but separated from it at the poles; epitheca hemispherical with a conical projection at the apex about 10.0 µm Iong and 20.0 µm wide, analogous with the apical horn present on many other dinoflagellates; hypotheca extended beyond the capsule antapically in the form of an irregular bilobed structure; vesicle surrounded equatorially by a well developed transverse furrow about 6.0 µm wide; furrow comprises two parallel ridges enclosing a concave groove; longitudinal furrow marked by a fold about 5.0 µm wide;
archeopyle apical with simple free operculum;
vesicle unplated;
color yellow;
Dimensions:
length of vesicle 60.0 (66.1) 73.0 µm; width of vesicle 38.0 (44.1) 48.4 µm; length of capsule 38.0 (42.4) 49.5 µm; width of capsule 35.0 (40.1) 45.0 µm.
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Supplemental description: [Jansonius, 1986, p. 202]:
Description:
(Holotype) 69 x 46 µm. Wall two layered; outer layer ca 0.4 µm thick, transparent pale yellow to almost hyaline, surface more or less irregular with scattered granules (0.2-0.5 µm); inner wall medium yellow, 0.8 µm thick, surface scabrategranulate with dense sculpture of (partly fused) low granules (0.3-0.6 µm); apical pericoel ca 10 µm high, antapical pericoel ca 8-10 µm, gradually dwindling to nothing near the cingulum; at cingulum and precingulars outer layer tightly stretched over inner body, but not fused with it; cingulum indicated by shallow depression on inner body, by low ridges or folds on outer layer, 6 µm wide, strongly spiraling, at the sulcus its ends offset by ca 12 µm; 2a intercalary delineated in inner body by narrow groove, with lateral traces extending from it suggesting presence of 1a, and 3a, and 4"; on ventral side a linear feature possibly corresponding with the edge of the apicals, or with a line of weakness in the outer layer (apical archeopyle?). No other traces of paratabulation can be discerned.
Remarks:
The other specimen illustrated in Pocock (1972) could not be located, the slide number and coordinates given by Pocock (1972) for pl. 22, fig. 14 actually are those of the holotype of Murospora mesozoica Pocock 1961. Original (1972) position of holotype on slide was in ventral aspect; it was overlying a strongly birefringent fiber which made photography and examination in interference contrast difficult (Plate 6, fig. 1-3). After warming of the glycerine jelly and agitation of the residue, the specimen rotated to a dorsal aspect, and was photographed in detail (Plate 6, fig. 4-7). The numbering of the intercalary plates in the description is used for discussion only, on the presumption that this form has a normal peridinioid tabulation.
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Courtinant, 1989, p.214: (Translation: LPP):
Remark:
The combination proposed by Helenes is accepted; but the author"s recommendation to reserve the name for type specimens only, in not followed. The morphological characteristics of this species are sufficiently distinct to be used. the archaeopyle margin suggests the existence of anterior intercalary paraplates, which justifies the transfer by Helenes.
NOW Ovoidinium. Originally Evittia (generic name illegitimate), subsequently Pocockia, thirdly (and now) Ovoidinium, fourthly Ascodinium. Lentin and Williams (1989, p.270) retained this species in Ovoidinium.
Holotype: Pocock, 1972, pl.22, fig.14
Locus typicus: Tidewater Davidson Crown, Western Canada
Stratum typicum: ?Toarcian-?Bajocian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Evittia waltonii: [Pocock, 1972, p. 93]:
Description:
Vesicle somewhat flattened dorso-ventrally; capsule ovoid to sub-spherical; scabrate; 1.0-1.5 µm thick; enveloped by a thin outer wall that is appressed to the capsule equatorially but separated from it at the poles; epitheca hemispherical with a conical projection at the apex about 10.0 µm Iong and 20.0 µm wide, analogous with the apical horn present on many other dinoflagellates; hypotheca extended beyond the capsule antapically in the form of an irregular bilobed structure; vesicle surrounded equatorially by a well developed transverse furrow about 6.0 µm wide; furrow comprises two parallel ridges enclosing a concave groove; longitudinal furrow marked by a fold about 5.0 µm wide;
archeopyle apical with simple free operculum;
vesicle unplated;
color yellow;
Dimensions:
length of vesicle 60.0 (66.1) 73.0 µm; width of vesicle 38.0 (44.1) 48.4 µm; length of capsule 38.0 (42.4) 49.5 µm; width of capsule 35.0 (40.1) 45.0 µm.
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Supplemental description: [Jansonius, 1986, p. 202]:
Description:
(Holotype) 69 x 46 µm. Wall two layered; outer layer ca 0.4 µm thick, transparent pale yellow to almost hyaline, surface more or less irregular with scattered granules (0.2-0.5 µm); inner wall medium yellow, 0.8 µm thick, surface scabrategranulate with dense sculpture of (partly fused) low granules (0.3-0.6 µm); apical pericoel ca 10 µm high, antapical pericoel ca 8-10 µm, gradually dwindling to nothing near the cingulum; at cingulum and precingulars outer layer tightly stretched over inner body, but not fused with it; cingulum indicated by shallow depression on inner body, by low ridges or folds on outer layer, 6 µm wide, strongly spiraling, at the sulcus its ends offset by ca 12 µm; 2a intercalary delineated in inner body by narrow groove, with lateral traces extending from it suggesting presence of 1a, and 3a, and 4"; on ventral side a linear feature possibly corresponding with the edge of the apicals, or with a line of weakness in the outer layer (apical archeopyle?). No other traces of paratabulation can be discerned.
Remarks:
The other specimen illustrated in Pocock (1972) could not be located, the slide number and coordinates given by Pocock (1972) for pl. 22, fig. 14 actually are those of the holotype of Murospora mesozoica Pocock 1961. Original (1972) position of holotype on slide was in ventral aspect; it was overlying a strongly birefringent fiber which made photography and examination in interference contrast difficult (Plate 6, fig. 1-3). After warming of the glycerine jelly and agitation of the residue, the specimen rotated to a dorsal aspect, and was photographed in detail (Plate 6, fig. 4-7). The numbering of the intercalary plates in the description is used for discussion only, on the presumption that this form has a normal peridinioid tabulation.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Courtinant, 1989, p.214: (Translation: LPP):
Remark:
The combination proposed by Helenes is accepted; but the author"s recommendation to reserve the name for type specimens only, in not followed. The morphological characteristics of this species are sufficiently distinct to be used. the archaeopyle margin suggests the existence of anterior intercalary paraplates, which justifies the transfer by Helenes.