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Australiella tripartita

Australiella tripartita, (Cookson and Eisenack, 1960), Vozzhennikova, 1967; Emendation as Deflandrea tripartita: Cookson and Manum, 1964, p. 521-522

Now Chatangiella. Originally Deflandrea, subsequently Australiella, thirdly (and now) Chatangiella.

Holotype: Cookson and Eisenack, 1960, pl. 1, fig. 10; Cookson and Manum, 1964, pl.76, figs.1-2
Locus typicus: North od Gingin, Perth Basin, Western Australia
Stratum typicum: ?Turonian to Middle Senonian

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Original description as Deflandrea tripartiata: [Cookson and Eisenack, 1960, p. 2-3]:

Description:
Shell elongate, somewhat flat, divided approximately equally by a shallow, circular girdle, the borders of which form re-entrant angles on both sides. The middle portion of the shell, which is almost entirely filled with a large capsule, is widest at the girdle, narrowing from thence, rather abruptly, both proximally and distally. Above the upper limit of the capsule the shell again bulges prominently before terminating in a short, broad, bluntly pointed horn. The distal portion of the shell, i. e., the portion below the lower limit of the capsule, is straight sided, truncate, and prolonged on one side into a short pointed horn. The shell-membrane is rather sparsely, finely to coarsely granular. The capsular membrane is more finely and closely granular. The pylome is circular to hoof-shaped.

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Emended description:

Cookson and Manum, 1964, p. 521-522:

Description:
Emended on the basis of the holotype. Theca elongate, equally divided by an inconspicuous girdle. The middle portion of the theca, which is almost entirely filled with a large capsule, is widest in the region of the girdle and rather abruptly narrowed from thence towards both the upper and lower limits of the capsule. Above the upper limit of the capsule the theca bulges prominently before terminating in a short, broad, bluntly pointed horn. The theca-membrane is c. 1.0 µm thick and perfectly smooth in optical section; in surface view a fine pattern is faintly visible under an oil immersion lens (n.a. > 1.0 µm). The wall of the capsule, which is finely but distinctly granular, varies in thickness being c. 2.5 µm anteriorly and posteriorly and c. 1.0 µm where it is in contact with the theca. The intercalary archeopyle is somewhat elongate and trapezium-shaped.

Affinities:
The girdle in the holotype is ill-defined and mainly indicated by two pairs of short, low, parallel ridges, one on either side of the ventral surface at short distances from the lateral margins of the theca. The direction of these ridges indicates that the girdle was slightly laevo-rotatory. In the middle of the dorsal surface, a fold-like line which seems to represent a portion of the girdle and its borders is indicated. The apparent discontinuity of the girdle on the ventral surface suggests that it may have been "broken" in a manner similar to that characterizing certain other species of Deflandrea (Manum 1963), including D. victoriensis. As in these forms, the more prominent antapical horn in D. tripartita is on the left hand side of the hypotheca.
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