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Aireiana verrucosa
Aireiana verrucosa, Cookson and Eisenack, 1965; Emendation: Stover, 1975
Holotype: Cookson and Eisenack, 1965, pl.14, figs.11-12.
Locus typicus: Browns Creek, SW. Victoria
Stratum typicum: Late Eocene
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Original description: [Cookson and Eisenack, 1965, p. 127]
Description:
Shell dorsoventral, almost spherical, rather thick-walled (c. 3-4 µm) with short apical and antapical prominences. In the type the apical prominence is short (c. 5 µm), relatively broad, and concave distally; the antapical one is larger (c. 12 µm long), conical, and of fibrillar construction. A few wart-like outgrowths of variable size have occurred on the general surface of all the examples examined, at least some of them being composed of short, straight fibrils, the distal ends of which are united (Pl. 14, fig. 13).
The dorsal surface of the type (Pl.14, fig.12) is partially ornamented with dot-like thickenings, a relatively wide, approximately equatorial portion being unornamented. This area, suggestive of a girdle-zone, is partly outlined by two sets of three individual but closely approximated thickenings of characteristic appearance on one side of the mid-line. On the other side, thickenings are also present but they are fewer, smaller, and less regularly arranged. The ornament of the ventral surface of the type (Pl. 14, fig. 11) consists of short, closely intertwined curved ridges, except in a median longitudinal area in the antapical portion of the shell where the wall is smooth.
The shell opens by a large rounded trapezoid archeopyle.
Dimensions:
Holotype: overall length c. 95 µm; shell c. 78 µm long, c. 76 µm wide.
Range: overall length 76-95 µm; shell c. 68-78 µm.
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Revised description:
Stover, 1975, p.43-44:
Description:
Cyst spherical to broadly ellipsoidal and composed of 2 appressed wall layers. Endophragm about 1.5 µm thick and smooth; periphragm less than 1 µm thick, usually with indistinct, irregularly reticulate to somewhat vermiculate sculpturing (Pl. 3, fig. 3e, 4a, 9), or with isolated, poorly delineated low granulae. Periphragm elevated locally to form 14 to 16 (possibly 17) cylindrical to conate intratabular processes that are closed distally (Pl. 3, fig. 7).
Process formula gonyaulacacean; 1-3", 6", 0c, 5""", 1p, 1""""(Text-fig. 7).
Processes 6 µm to 10 µm high, basal diameters 8 µm to 20 µm, with unevenly thickened surfaces. Apical area may have only 1 fairly large process, or it may have a large one with 1 or 2 small processes next to it. Processes adjacent to sulcal area usually poorly defined; those relatively closely spaced may coalesce.
Archeopyle precingular, Type P, and formed by release of plate 3" only.
Overall size 68 µm to 87 µm.
Variability:
Apparently the periphragam is not firmly attached to the endophragm, consequently specimens with nearly all or some of the periphragm missing are more numerous than those with entire periphragms. Exclusive of differences in the size and shape of the processes and the completeness of the periphragm, there seems to be little variation among specimens of Aireiana verrucosa. Because the species is known from relatively few and mostly damaged specimens (including the holotype), its range of morphological variability is unknown.
Holotype: Cookson and Eisenack, 1965, pl.14, figs.11-12.
Locus typicus: Browns Creek, SW. Victoria
Stratum typicum: Late Eocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1965, p. 127]
Description:
Shell dorsoventral, almost spherical, rather thick-walled (c. 3-4 µm) with short apical and antapical prominences. In the type the apical prominence is short (c. 5 µm), relatively broad, and concave distally; the antapical one is larger (c. 12 µm long), conical, and of fibrillar construction. A few wart-like outgrowths of variable size have occurred on the general surface of all the examples examined, at least some of them being composed of short, straight fibrils, the distal ends of which are united (Pl. 14, fig. 13).
The dorsal surface of the type (Pl.14, fig.12) is partially ornamented with dot-like thickenings, a relatively wide, approximately equatorial portion being unornamented. This area, suggestive of a girdle-zone, is partly outlined by two sets of three individual but closely approximated thickenings of characteristic appearance on one side of the mid-line. On the other side, thickenings are also present but they are fewer, smaller, and less regularly arranged. The ornament of the ventral surface of the type (Pl. 14, fig. 11) consists of short, closely intertwined curved ridges, except in a median longitudinal area in the antapical portion of the shell where the wall is smooth.
The shell opens by a large rounded trapezoid archeopyle.
Dimensions:
Holotype: overall length c. 95 µm; shell c. 78 µm long, c. 76 µm wide.
Range: overall length 76-95 µm; shell c. 68-78 µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised description:
Stover, 1975, p.43-44:
Description:
Cyst spherical to broadly ellipsoidal and composed of 2 appressed wall layers. Endophragm about 1.5 µm thick and smooth; periphragm less than 1 µm thick, usually with indistinct, irregularly reticulate to somewhat vermiculate sculpturing (Pl. 3, fig. 3e, 4a, 9), or with isolated, poorly delineated low granulae. Periphragm elevated locally to form 14 to 16 (possibly 17) cylindrical to conate intratabular processes that are closed distally (Pl. 3, fig. 7).
Process formula gonyaulacacean; 1-3", 6", 0c, 5""", 1p, 1""""(Text-fig. 7).
Processes 6 µm to 10 µm high, basal diameters 8 µm to 20 µm, with unevenly thickened surfaces. Apical area may have only 1 fairly large process, or it may have a large one with 1 or 2 small processes next to it. Processes adjacent to sulcal area usually poorly defined; those relatively closely spaced may coalesce.
Archeopyle precingular, Type P, and formed by release of plate 3" only.
Overall size 68 µm to 87 µm.
Variability:
Apparently the periphragam is not firmly attached to the endophragm, consequently specimens with nearly all or some of the periphragm missing are more numerous than those with entire periphragms. Exclusive of differences in the size and shape of the processes and the completeness of the periphragm, there seems to be little variation among specimens of Aireiana verrucosa. Because the species is known from relatively few and mostly damaged specimens (including the holotype), its range of morphological variability is unknown.