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Wallodinium contortum
Plate 4, figures 6–11
Derivation of name
After the strongly contorted morphology.
Holotype: Plate 4, figure 7. Texaco Wolfbutton 32-7-8, 6100 ft., slide 1, EF T24/3, 48 µm maximum width.
Description
Circumcavate cyst, pylome presumed apical, but no indications of tabulation. Operculum not evident. Endophragm very thin, centrally located, with a slightly curved or asymmetrical ovoid outline, approximately twice as long as broad but commonly not evident. Periphragm thicker, characteristically contorted into a ‘C’ shape, curvature such that presumed hypotheca is at least parallel to epitheca, often with apex nearly in contact with antapex. Periphragm unornamented. Apical region flared slightly into trumpet-like shape. No evidence of cingulum or any other feature indicating tabulation, but a subtle narrowing of the cyst often occurs in a position likely to be cingular.
Dimensions
The contortion and essentially circular outline of compressed specimens renders measurement in a uniform morphologic orientation difficult; 61.8–80.2 72.2 average) µm maximum dimension; 20.4–33.4 (28.4 average) µm pylome width; 30.1–40.1 (34.2 average) µm medial width (12 specimens measured).
Comments
Wallodinium contortum is distinguished from W. lunum (Plate 4, figures 14, 15) by being curved to a much greater extent, and having a thicker periphragm and less distinct endophragm.
Occurrence
Rare, Albian, Torok-Nanushuk Formations, north Alaska.
Derivation of name
After the strongly contorted morphology.
Holotype: Plate 4, figure 7. Texaco Wolfbutton 32-7-8, 6100 ft., slide 1, EF T24/3, 48 µm maximum width.
Description
Circumcavate cyst, pylome presumed apical, but no indications of tabulation. Operculum not evident. Endophragm very thin, centrally located, with a slightly curved or asymmetrical ovoid outline, approximately twice as long as broad but commonly not evident. Periphragm thicker, characteristically contorted into a ‘C’ shape, curvature such that presumed hypotheca is at least parallel to epitheca, often with apex nearly in contact with antapex. Periphragm unornamented. Apical region flared slightly into trumpet-like shape. No evidence of cingulum or any other feature indicating tabulation, but a subtle narrowing of the cyst often occurs in a position likely to be cingular.
Dimensions
The contortion and essentially circular outline of compressed specimens renders measurement in a uniform morphologic orientation difficult; 61.8–80.2 72.2 average) µm maximum dimension; 20.4–33.4 (28.4 average) µm pylome width; 30.1–40.1 (34.2 average) µm medial width (12 specimens measured).
Comments
Wallodinium contortum is distinguished from W. lunum (Plate 4, figures 14, 15) by being curved to a much greater extent, and having a thicker periphragm and less distinct endophragm.
Occurrence
Rare, Albian, Torok-Nanushuk Formations, north Alaska.