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Sahulidinium ottii
Shaluhidinium ottii Stover and Helby, 1987
Holotype: Stover and Helby, 1987, fig.13I-J
Paratypes: Stover and Helby, 1987
Locus typicus: Bonaparte Basin, Australia
Stratum typicum: Anisian-Ladinian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Sahulidinium ottii Stover and Helby, 1987a. S.ottii has the tabulation formula 7', 6a, 7". The autophragm is ornamented with coni, granules and or spinules up to 2.5 µm in length. Ornamentation usually nontabular but may indicate parasutural rows. Archeopyle apical and with short accessory sutures between some anterior intercalary paraplates. Opercula commonly attached. Paracingulum when indicated is much nearer the antapical end.The six anterior intercalary plates are large, and are longitudinally elongate, bigeniculate. The precingulars are camerate except for the planate 1". Size: length 80-112 µm, width 32-50 µm.
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Original description: Stover and Helby, 1987, p.113-114
Cysts proximate, elongate ellipsoidal in dorsoventral view and arcuate-reniform in lateral view. Autophragm thin (less than 1 µm), and ornamented with coni, granules and/or spinules up to 2.5 µm in length (generally less than 1.5 µm) and 1 µm or less in diameter. Ornamentation features solid, mainly nontabular, but some arranged in short, usually discontinuous parasutural rows. Archeopyle apical, type [tA], the principal suture zigzag (Fig.12A,B) and usually with short accessory sutures between some anterior intercalary paraplates. Opercula commonly attached. Paratabulation expressed incompletely by the archeopyle and additionally on some specimens by discontinuous parasutural features, 6 - ?7', 6a, 7'', Xc for the epicyst (Fig.12A,B). Paratabulation of the hypocyst not determined. Paracingulum, when indicated, much nearer antapical than apical end; epicyst significantly larger than the hypocyst. Paracingulum undivided, helicoidal, with ends offset by a distance equal to the width of the paracingulum and indicated by transverse parasutural features and/or by a reduction in size or the absence of ornamentation. Except for vague indications on the midventral surface of the hypocyst, the parasulcus not expressed. Specimens 80 (93) 112 µm in length, 32 (41) 50 µm in width.
Paratabulation. On Sahulidinium ottii, indications of paratabulation are at best vague, discontinuous, and inconsistent. On some specimens, there is essentially no evidence of paratabulation; on others convincing evidence, albeit incomplete, is discernible. We interpreted the paratabulation (Fig. 12A,B) on about 25 specimens, of which about half are incomplete. Indications of paratabulation include primary and accessory archeopyle sutures, occasional parasutural alignment of the ornamentation and faint linear markings usually in the subequatorial region. The last was especially helpful in determining the configuration of precingular paraplates. The apical series consists of 6 or 7 paraplates. Those labelled 2' through 6' in Fig.12A,B are reasonably well documented. However, we were unable to ascertain whether one or two paraplates are present on the ventral surface. Dashed lines on the anterior ventral surface (Fig.12A) mark more speculative interpretations. Also, parasutural features delimiting apical paraplates laterally die out anteriorly, hence, arrangement of the apical series at and immediately adjacent to the apex is unknown. The 6 anterior intercalary paraplates are large, relative to others on the epicyst, and are longitudinally elongate, 6-sided, bigeniculate, and similar in size. Of the 7 precingular paraplates, all are relatively small, 5-sided and gabled anteriorly, except for 1'', which appears to be rectangular. Paraplate 7" is about as wide as it is high, whereas others in the precingular series are wider than they are high. Indications of paratabulation on the hypocyst are faint, and no definitive pattern was determined. On 2 specimens, an ill-defined, shallow, midventral depression, whose outline is depicted by dashed lines on the hypocyst (Fig. 12A) may represent a posterior sulcal paraplate. Even though the paratabulation of S. ottii is not known completely, enough is evident to indicate some similarity between its epicystal paratabulation and that on Rhaetogonyaulax. It would appear that the socalled rhaetogonyaulaceaen style is present in the Middle Triassic.
Holotype: Stover and Helby, 1987, fig.13I-J
Paratypes: Stover and Helby, 1987
Locus typicus: Bonaparte Basin, Australia
Stratum typicum: Anisian-Ladinian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Sahulidinium ottii Stover and Helby, 1987a. S.ottii has the tabulation formula 7', 6a, 7". The autophragm is ornamented with coni, granules and or spinules up to 2.5 µm in length. Ornamentation usually nontabular but may indicate parasutural rows. Archeopyle apical and with short accessory sutures between some anterior intercalary paraplates. Opercula commonly attached. Paracingulum when indicated is much nearer the antapical end.The six anterior intercalary plates are large, and are longitudinally elongate, bigeniculate. The precingulars are camerate except for the planate 1". Size: length 80-112 µm, width 32-50 µm.
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Original description: Stover and Helby, 1987, p.113-114
Cysts proximate, elongate ellipsoidal in dorsoventral view and arcuate-reniform in lateral view. Autophragm thin (less than 1 µm), and ornamented with coni, granules and/or spinules up to 2.5 µm in length (generally less than 1.5 µm) and 1 µm or less in diameter. Ornamentation features solid, mainly nontabular, but some arranged in short, usually discontinuous parasutural rows. Archeopyle apical, type [tA], the principal suture zigzag (Fig.12A,B) and usually with short accessory sutures between some anterior intercalary paraplates. Opercula commonly attached. Paratabulation expressed incompletely by the archeopyle and additionally on some specimens by discontinuous parasutural features, 6 - ?7', 6a, 7'', Xc for the epicyst (Fig.12A,B). Paratabulation of the hypocyst not determined. Paracingulum, when indicated, much nearer antapical than apical end; epicyst significantly larger than the hypocyst. Paracingulum undivided, helicoidal, with ends offset by a distance equal to the width of the paracingulum and indicated by transverse parasutural features and/or by a reduction in size or the absence of ornamentation. Except for vague indications on the midventral surface of the hypocyst, the parasulcus not expressed. Specimens 80 (93) 112 µm in length, 32 (41) 50 µm in width.
Paratabulation. On Sahulidinium ottii, indications of paratabulation are at best vague, discontinuous, and inconsistent. On some specimens, there is essentially no evidence of paratabulation; on others convincing evidence, albeit incomplete, is discernible. We interpreted the paratabulation (Fig. 12A,B) on about 25 specimens, of which about half are incomplete. Indications of paratabulation include primary and accessory archeopyle sutures, occasional parasutural alignment of the ornamentation and faint linear markings usually in the subequatorial region. The last was especially helpful in determining the configuration of precingular paraplates. The apical series consists of 6 or 7 paraplates. Those labelled 2' through 6' in Fig.12A,B are reasonably well documented. However, we were unable to ascertain whether one or two paraplates are present on the ventral surface. Dashed lines on the anterior ventral surface (Fig.12A) mark more speculative interpretations. Also, parasutural features delimiting apical paraplates laterally die out anteriorly, hence, arrangement of the apical series at and immediately adjacent to the apex is unknown. The 6 anterior intercalary paraplates are large, relative to others on the epicyst, and are longitudinally elongate, 6-sided, bigeniculate, and similar in size. Of the 7 precingular paraplates, all are relatively small, 5-sided and gabled anteriorly, except for 1'', which appears to be rectangular. Paraplate 7" is about as wide as it is high, whereas others in the precingular series are wider than they are high. Indications of paratabulation on the hypocyst are faint, and no definitive pattern was determined. On 2 specimens, an ill-defined, shallow, midventral depression, whose outline is depicted by dashed lines on the hypocyst (Fig. 12A) may represent a posterior sulcal paraplate. Even though the paratabulation of S. ottii is not known completely, enough is evident to indicate some similarity between its epicystal paratabulation and that on Rhaetogonyaulax. It would appear that the socalled rhaetogonyaulaceaen style is present in the Middle Triassic.