Australisphaera DAVEY 1978 emend. DUXBURY 1983

Emended diagnosis:

"Proximate, ceratiacean dinoflagellate cysts which are single-walled, dorso-ventrally flattened and have lateral and antapical features developed as unusually high ornament or low to high, hollow, distally closed horns. Overall, the ornament may be low, but spines may occur, usually concentrated at horn terminations, sometimes extending the horns considerably. Vague paratabulation may be indicated by ornament alignment. The archeopyle is apical with a zig-zag margin and the parasulcus is offset to the left of the mid-line." - From Duxbury (1983, p. 25).

Note:

The genus Australisphaera Davey 1978 has later been emended by Harding (1986a, p. 100), however, see Harding (1990b, p. 21).

(See Williams et al., 1998).



Australisphaera vitrea DUXBURY 1983

Paratype
Pl. 3, fig(s). 5
NHM registration number: FD44(1)
 

Transmitted light images:

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Ventral face in high focus
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Optical section
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Dorsal face in low focus
 

Original diagnosis:

"A fairly thick-walled dinoflagellate cyst species bearing two lateral horns and one or two antapical horns. The lateral horns are short and broad and display a paracingular notch at their distal extremes. Short, posteriorly-directed, digitate projections extend from below the lateral post-paracingular margins and these are hollow and taper to sharp points. One large, conical, left antapical horn is always present and a right antapical horn is sometimes indicated by a very low protuberance. The single body layer is glassy in appearance and is covered by granular ornament which is particularly concentrated at the extremes of the horns. In the case of the antapical horns, coarse ornament is present in the position of the right antapical, whether the wall protrudes at that point or not. The archeopyle is apical." - From Duxbury (1983, p. 26).

Note:

This species has later been questionably assigned to the genus Nyktericysta Bint 1986. Now: Nyktericysta? vitrea (Duxbury 1983) Bint 1986.

(See Williams et al., 1998).