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Hadriana cinctum
Hadriana cinctum Riding and Helby, 2001f, p.155,157, figs.8A-I,9A-L. Holotype: Riding and Helby, 2001f, figs.8G-I.
The epithet is avowedly based on the Latin noun cinctum (girdle or zone) and thus should be cited as "cinctum", not "cincta" as indicated in Riding and Helby. N.I.A. Age: Kimmeridgian-Tithonian.
Original description Riding and Helby 2001f
1978 Adnatosphaeridum sp.; Chen, p. 78, fig. 55-431
Previous Australian usage: MP 528 - Helby,
?Ridaugella sp. A - Parker (1986, pl. 22, figs 1,2).
Description. A species of Hadriana which is slightly dorsoventrally flattened and flat to slightly indented at the parasulcus. It has an ellipsoidal cyst body, which is consistently wider than long. The autophragm is smooth to microscabrate and 1-1.5 µm thick. The prominent perforate to trabeculate ectophragm is also significantly wider than long, imparting a squat shape to many specimens; it is smooth and 0.5-1µm thick. For the most part the epicystal wall is generally not obviously layered. However, an ectocoel opens near the base of the precingular paraplate series and spreadsd, girdle-like, posteriorly from the paracingular region and generally leaving a wide polar opening. The ectophragm is connected to the cyst body by short postcingular and paracingular processes, which may be intratabula in location. The processes are solid and expand proximally. They also expand distally where they are subsumed into the ectophragm. There is a characteristic gap, which is widest in the interprocess areas, between the top of the ectophragm and the cyst body in polar view. The trabecular girdle is widest close to the base of the autophragm, naroowing marginally antapically. The antapical hole in the ectophragm is large and ellipsoidal in shape; it is located well below the antapex of the autocyst. The margin is interrupted by five distinctive polygonal areas of ectophragm which are relaively free of perforations, or have small (<1µm in diameter) lacunae from 1 to 8 µm in diameter. Alternatively, many specimens are largely trabeculate with a network of anastomosing solid, slender, ribbon-like elements. These elements are normally between 1.5 and 4 µm, but occasionally may attain 10µm in width. Rarely, individuals are partially perforate and partially trabeculate.
Dimensions (µm; n=40): Min. (Mean) Max.
Length of ectocyst (excl. operculum): 84 (106) 140
Length of autocyst (excl. operculum): 46 (61) 79
Dorsoventral width of ectocyst: 114 (141) 181
Dorsoventral width of autocyst: 57 (72) 93
Lateral width of ectocyst: 101 (112) 145
Lateral width of autocyst: 58 (65) 75
Width of ectocoel at antapex: 12 (36) 76
Width of ectocoel in the postcingular series: 30 (45) 73
Height of postcingular processes: 7 (14) 22
The measured specimens are from a ditch cuttings sample in Hadrian-1 well between 3285.00m and 3300.00m and a sidewall core sample at 3087.00m from Cockell-1 well.
Comments.
Most of the material studied are loisthocysts. The longitudonal flattening of the cyst body is consistent and is a good recognitional criterion in poorly preserved material. The most characteristic feature of this species is the prominent and variable girdle-like ectophragm, which emerges close to the base of the precingular paraplate series. This ectophragm overlies the hypocystal autophragm and is open antapically. The antapical margin of the ectophragm in dorsoventral view is characteristically interrupted due to the occurence of the postcingular 'nodes'. The paracingular and postcingular processes are variable. The majority are solid; but a few appear to be funnel-like. There is a tendency for the solid processes to break. The processes are best observed in polar view.
Comparison.
Hadriana cincta is broadly similar to Belowia baltea Riding and Helby 2001f in size and overall morphology. However. B. baltea is generally compressed in polar view, has a paracingular protuberance and commonly a solid antapical girdle. It is distinguished from large chorate cysts with apical archaeopyles in lacking large intratabular processes and process complexes. Because of the general morphologicla similarities in Belowia, Hadriana and Rigaudella, which then evolved into the Kimmeridgian genus Hadrian, which gave rise to Belowia in the Tithonian (Riding and Helby, 2001f).
Derivation of name. From the Latin cinctum meaning girdle, or zone, and referring to the characteristic, extensive, skirt-like development of ectophragm which emerges on the epicyst and extends beyond the antapex of the cyst body.
Holotype and type locality. Figs 8G-I, CPC 35687, Hadrian-1 well, ditch cuttings between 3285.00m and 3300.00m.
Stratigraphical distribution.
Hadriana cincta has been recorded from the Kimmeridgian Dingodinium swanense Zone (6aiia) to the Tithonian Cribroperidinium perforans Zone (5d) in Australia and Papua New Guinea (Foster, this volume; Helby and Partridge, in prep). It is recorded as Adnatosphaeridium sp. from Late Jurassic ditch cuttings in the Ankamotra-1 well in western Madagascar (Chen, 1978). It is also recorded as Thalassiphora sp. from the Sembar Fomation of Pakistan (Beju, 1979, pl. 32, figs 4-6; 1980).
The epithet is avowedly based on the Latin noun cinctum (girdle or zone) and thus should be cited as "cinctum", not "cincta" as indicated in Riding and Helby. N.I.A. Age: Kimmeridgian-Tithonian.
Original description Riding and Helby 2001f
1978 Adnatosphaeridum sp.; Chen, p. 78, fig. 55-431
Previous Australian usage: MP 528 - Helby,
?Ridaugella sp. A - Parker (1986, pl. 22, figs 1,2).
Description. A species of Hadriana which is slightly dorsoventrally flattened and flat to slightly indented at the parasulcus. It has an ellipsoidal cyst body, which is consistently wider than long. The autophragm is smooth to microscabrate and 1-1.5 µm thick. The prominent perforate to trabeculate ectophragm is also significantly wider than long, imparting a squat shape to many specimens; it is smooth and 0.5-1µm thick. For the most part the epicystal wall is generally not obviously layered. However, an ectocoel opens near the base of the precingular paraplate series and spreadsd, girdle-like, posteriorly from the paracingular region and generally leaving a wide polar opening. The ectophragm is connected to the cyst body by short postcingular and paracingular processes, which may be intratabula in location. The processes are solid and expand proximally. They also expand distally where they are subsumed into the ectophragm. There is a characteristic gap, which is widest in the interprocess areas, between the top of the ectophragm and the cyst body in polar view. The trabecular girdle is widest close to the base of the autophragm, naroowing marginally antapically. The antapical hole in the ectophragm is large and ellipsoidal in shape; it is located well below the antapex of the autocyst. The margin is interrupted by five distinctive polygonal areas of ectophragm which are relaively free of perforations, or have small (<1µm in diameter) lacunae from 1 to 8 µm in diameter. Alternatively, many specimens are largely trabeculate with a network of anastomosing solid, slender, ribbon-like elements. These elements are normally between 1.5 and 4 µm, but occasionally may attain 10µm in width. Rarely, individuals are partially perforate and partially trabeculate.
Dimensions (µm; n=40): Min. (Mean) Max.
Length of ectocyst (excl. operculum): 84 (106) 140
Length of autocyst (excl. operculum): 46 (61) 79
Dorsoventral width of ectocyst: 114 (141) 181
Dorsoventral width of autocyst: 57 (72) 93
Lateral width of ectocyst: 101 (112) 145
Lateral width of autocyst: 58 (65) 75
Width of ectocoel at antapex: 12 (36) 76
Width of ectocoel in the postcingular series: 30 (45) 73
Height of postcingular processes: 7 (14) 22
The measured specimens are from a ditch cuttings sample in Hadrian-1 well between 3285.00m and 3300.00m and a sidewall core sample at 3087.00m from Cockell-1 well.
Comments.
Most of the material studied are loisthocysts. The longitudonal flattening of the cyst body is consistent and is a good recognitional criterion in poorly preserved material. The most characteristic feature of this species is the prominent and variable girdle-like ectophragm, which emerges close to the base of the precingular paraplate series. This ectophragm overlies the hypocystal autophragm and is open antapically. The antapical margin of the ectophragm in dorsoventral view is characteristically interrupted due to the occurence of the postcingular 'nodes'. The paracingular and postcingular processes are variable. The majority are solid; but a few appear to be funnel-like. There is a tendency for the solid processes to break. The processes are best observed in polar view.
Comparison.
Hadriana cincta is broadly similar to Belowia baltea Riding and Helby 2001f in size and overall morphology. However. B. baltea is generally compressed in polar view, has a paracingular protuberance and commonly a solid antapical girdle. It is distinguished from large chorate cysts with apical archaeopyles in lacking large intratabular processes and process complexes. Because of the general morphologicla similarities in Belowia, Hadriana and Rigaudella, which then evolved into the Kimmeridgian genus Hadrian, which gave rise to Belowia in the Tithonian (Riding and Helby, 2001f).
Derivation of name. From the Latin cinctum meaning girdle, or zone, and referring to the characteristic, extensive, skirt-like development of ectophragm which emerges on the epicyst and extends beyond the antapex of the cyst body.
Holotype and type locality. Figs 8G-I, CPC 35687, Hadrian-1 well, ditch cuttings between 3285.00m and 3300.00m.
Stratigraphical distribution.
Hadriana cincta has been recorded from the Kimmeridgian Dingodinium swanense Zone (6aiia) to the Tithonian Cribroperidinium perforans Zone (5d) in Australia and Papua New Guinea (Foster, this volume; Helby and Partridge, in prep). It is recorded as Adnatosphaeridium sp. from Late Jurassic ditch cuttings in the Ankamotra-1 well in western Madagascar (Chen, 1978). It is also recorded as Thalassiphora sp. from the Sembar Fomation of Pakistan (Beju, 1979, pl. 32, figs 4-6; 1980).