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Chiropteridium haigii
Chiropteridium haigii, Backhouse, 2006, p. 58,60, pl.1, figs.1–8.
Holotype: Backhouse, 2006, pl.1, figs.1–2.
Holotype: Backhouse, 2006, Plate 1, figs 1, 2,
Paratype: Backhouse, 2006, Plate 1, figs 5, 6,
Type stratum: Lower Gearle Siltstone, upper Lower to Middle Albian.
Stratigraphic range: in Southern Carnarvon Basin - appears in the uppermost part of the Diconodinium davidii Zone; in Boologooro-1 - top of the Canninginopsis denticulata Zone, not present above the Canninginopsis denticulata Zone in this study; although sparse, questionable specimens are present as high as the Dioxya armata Zone.
Age: early-middle Albian.
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Original description: [Blackhouse, 2006]:
Description:
A small cyst, originally subspherical in shape, usually compressed into a partly folded, subcircular shape.
The autophragm is smooth and < 0.5 μm thick, entirely covered by numerous fine, short, non-tabular processes 1 μm to 1.5 μm long, too closely spaced and narrow to have a measurable thickness. The processes number several hundred on an individual cyst and support an ectophragm significantly less than 0.5 μm thick. The spines may be expanded at the tips in order to support the ectophragm, but this feature is not observable because of the small size. The surface of the ectophragm is essentially smooth.
The archeopyle is apical on the few specimens where this feature can be observed, and though the tabulation pattern of the archeopyle suture is not entirely known, it appears to be (tA). An archeopyle is evident on approximately 10% of specimens and can be observed near the margin of compressed cysts. On rare specimens, such as the holotype, the archeopyle suture exhibits an obvious plate margin outline and short accessory sutures.
The operculum remains attached on about half of the specimens that display an archeopyle.
An apical horn is not developed on the autophragm, but a few specimens show a slightly raised ectophragm in the apical region. The ectophragm also bulges slightly in the cingular area of a few specimens as observed at the cyst margin. No other tabular features are developed, so that if the archeopyle is not formed, or partially formed, cysts cannot be orientated and have the appearance of a small, subspherical, body with a granular surface.
Dimensions (40 specimens):
Length of complete cysts: 25.5 μm (28.1 μm) 32.5 μm. On cysts where the operculum has been detached, the length ranges from 18.0 μm to 28.0 μm. Width of complete cysts: 24 μm (28.7 μm) 32.5 μm.
Holotype: Length of cyst with the operculum removed: 26.5 μm; width: 30.5 μm.
Paratype: Specimen complete; length: 28.0 μm; width: 31.5 μm.
Remarks:
This species is somewhat tentatively assigned to Chlamydophorella because the precise nature of the archeopyle is still uncertain, though all the available evidence suggests it is a normal type (tA). If the archeopyle is (tA), Chlamydophorella haigii sp. nov. conforms to the original generic diagnosis of Cookson and Eisenack (1958). Chlamydophorella haigii sp. nov. is considerably smaller than the type species, Chlamydophorella nyei, but possesses a similar structure with an autophragm bearing numerous fine spines, of equal length, supporting a thin ectophragm. As in Chlamydophorella nyei the ectophragm may bulge slightly at the cingulum, but unlike Chlamydophorella nyei, an apical protrusion of the autophragm is not developed. Chlamydophorella? urna is slightly larger, but it is more ovoid, slightly angular and normally exhibits a cingulum.Chlamydophorella haigii sp. nov. appears to have been overlooked in previous accounts of Aptian and Albian dinoflagellate cysts, probably because of its small size, nondescript appearance and ill-defined dinoflagellate cyst features. Nevertheless, it is abundant over an interval ranging from the uppermost Windalia Radiolarite to the lower Gearle Siltstone. It appears as a small, round, amorphous object at low power, and even at x1000 it may not present distinguishable in of flagellate cyst characters. Only in specimens with suitable orientation can dinoflagellate cyst affinities be observed, usually the archeopyle and occasionally short accessory archeopyle sutures.
Holotype: Backhouse, 2006, pl.1, figs.1–2.
Holotype: Backhouse, 2006, Plate 1, figs 1, 2,
Paratype: Backhouse, 2006, Plate 1, figs 5, 6,
Type stratum: Lower Gearle Siltstone, upper Lower to Middle Albian.
Stratigraphic range: in Southern Carnarvon Basin - appears in the uppermost part of the Diconodinium davidii Zone; in Boologooro-1 - top of the Canninginopsis denticulata Zone, not present above the Canninginopsis denticulata Zone in this study; although sparse, questionable specimens are present as high as the Dioxya armata Zone.
Age: early-middle Albian.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Blackhouse, 2006]:
Description:
A small cyst, originally subspherical in shape, usually compressed into a partly folded, subcircular shape.
The autophragm is smooth and < 0.5 μm thick, entirely covered by numerous fine, short, non-tabular processes 1 μm to 1.5 μm long, too closely spaced and narrow to have a measurable thickness. The processes number several hundred on an individual cyst and support an ectophragm significantly less than 0.5 μm thick. The spines may be expanded at the tips in order to support the ectophragm, but this feature is not observable because of the small size. The surface of the ectophragm is essentially smooth.
The archeopyle is apical on the few specimens where this feature can be observed, and though the tabulation pattern of the archeopyle suture is not entirely known, it appears to be (tA). An archeopyle is evident on approximately 10% of specimens and can be observed near the margin of compressed cysts. On rare specimens, such as the holotype, the archeopyle suture exhibits an obvious plate margin outline and short accessory sutures.
The operculum remains attached on about half of the specimens that display an archeopyle.
An apical horn is not developed on the autophragm, but a few specimens show a slightly raised ectophragm in the apical region. The ectophragm also bulges slightly in the cingular area of a few specimens as observed at the cyst margin. No other tabular features are developed, so that if the archeopyle is not formed, or partially formed, cysts cannot be orientated and have the appearance of a small, subspherical, body with a granular surface.
Dimensions (40 specimens):
Length of complete cysts: 25.5 μm (28.1 μm) 32.5 μm. On cysts where the operculum has been detached, the length ranges from 18.0 μm to 28.0 μm. Width of complete cysts: 24 μm (28.7 μm) 32.5 μm.
Holotype: Length of cyst with the operculum removed: 26.5 μm; width: 30.5 μm.
Paratype: Specimen complete; length: 28.0 μm; width: 31.5 μm.
Remarks:
This species is somewhat tentatively assigned to Chlamydophorella because the precise nature of the archeopyle is still uncertain, though all the available evidence suggests it is a normal type (tA). If the archeopyle is (tA), Chlamydophorella haigii sp. nov. conforms to the original generic diagnosis of Cookson and Eisenack (1958). Chlamydophorella haigii sp. nov. is considerably smaller than the type species, Chlamydophorella nyei, but possesses a similar structure with an autophragm bearing numerous fine spines, of equal length, supporting a thin ectophragm. As in Chlamydophorella nyei the ectophragm may bulge slightly at the cingulum, but unlike Chlamydophorella nyei, an apical protrusion of the autophragm is not developed. Chlamydophorella? urna is slightly larger, but it is more ovoid, slightly angular and normally exhibits a cingulum.Chlamydophorella haigii sp. nov. appears to have been overlooked in previous accounts of Aptian and Albian dinoflagellate cysts, probably because of its small size, nondescript appearance and ill-defined dinoflagellate cyst features. Nevertheless, it is abundant over an interval ranging from the uppermost Windalia Radiolarite to the lower Gearle Siltstone. It appears as a small, round, amorphous object at low power, and even at x1000 it may not present distinguishable in of flagellate cyst characters. Only in specimens with suitable orientation can dinoflagellate cyst affinities be observed, usually the archeopyle and occasionally short accessory archeopyle sutures.