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Belodinium dysculum
Belodinium dysculum, Cookson and Eisenack, 1960
Stover and Helby, 1987, provided a revised description for this species.
Holotype: Cookson and Eisenack, 1960, pl.37, fig.10
Locus typicus: Canning Basin, W Australia
Stratum typicum: probably Tithonian
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Original description: [Cookson and Eisenack, 1960, p. 250]:
Description:
Shell elongate, 2,5-4 times longer than broad, divided unequally by a conspicuous girdle into larger epitheca and shorter hypotheca. The surfaces of the main body or capsule is divided by delicate, relatively high, sometimes undulate ledges into five yo six nearly rectangular or trapezoid fields in the epitheca and into an unascertained number of +/- isodiametric fields in the hypotheca; the ledges are supported by small spinules arranged in rows which arise from the surface of the capsule. The membrane which forms the ledges extends apically as a short, hollow, bluntly pointed horn and antapically as a hollow, rounded expansion which, in one example, appears to open terminally. A circle of rather strong spine-like processes is developed at the apical and antapical ends of the capsule. The shell apparently opens by the complete detachment of the apical part including the extreme anterior portion of the capsule.
Dimensions:
type- 97µm long, 42µm broad, capsule 60-32µm.
Range - length 76-108µm, breadth 24-42µm, capsule 48-57µm x20-32µm.
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Revised description:
Stover and Helby, 1987, p. 275:
Description:
Cysts proximate, elongate ellipsoidal, with a short apical horn and generally two, short, rounded or pointed, antapical horns, which may be equal in length, or the right horn may be shorter than the left horn, or absent. Cyst wall punctogranulate and variable in thickness from about 1.5 µm to slightly more than 2 µm.
Archeopyle apical, with principal suture much nearer the apex on the dorsal surface than on the ventral surface. Midventrally, archeopyle margin delimiting parasulcal notch. Small, usually gabled paraplate (Fig. 11A,B) to the left and slightly anterior to the notch, with lateral limits indicated by accessory sutures, with anterior edge marking an inflection along the left ventral archeopyle margin. Corresponding inflection not present along the right ventral margin, where, however, a slight convexity may occur. Operculum free.
Indications of paracingulum or of paratabulation, other than the archeopyle, absent. Anterior extent of a parasulcus inferred solely by parasulcal notch.
Dimensions:
Size range: length 83-108 µm; width 28-51 µm; specimens without opercula 18-27 µm shorter than complete specimens.
Affinities:
In the absence of features clearly denoting paratabulation we cannot confidently identify within the kofoidian system the small paraplate along the left archeopyle margin. Nevertheless, its presence imparts a characteristic asymmetry to the archeopyle margin. This asymmetry is also evident on some specimens of other species assigned to Batioladinium: for example, B. jaegeri (Alberti) Brideaux 1975 (see Brideaux, 1975, fig.3) and of B. longicornutum (Alberti) Brideaux 1975 (see Alberti, 1961, pl.5, fig.21). Brideaux (1975, p. 1241) indicated that the cysts of Batioladinium are somewhat flattened dorsoventrally. This does not appear to be a persistent character of B. micropodum.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Belodinium dysculum Cookson and Eisenack, 1960b, emend. Stover and Helby, 1987d, differs from B.obsoletum and B.asaphum in not having parasutural ornamentation, the latter two species were transferred to Clathroctenocystis by Stover and Helby (1987d) because of this feature. However, Dodekova (1990) retained obsoletum in Belodinium.
Size of Belodinium dysculum: overall without operculum 56-72 µm long, 39-42 µm wide, with operculum specimens are 20-36 µm longer. Processes 3-7 µm long, about 1 µm wide.
Stover and Helby, 1987, provided a revised description for this species.
Holotype: Cookson and Eisenack, 1960, pl.37, fig.10
Locus typicus: Canning Basin, W Australia
Stratum typicum: probably Tithonian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1960, p. 250]:
Description:
Shell elongate, 2,5-4 times longer than broad, divided unequally by a conspicuous girdle into larger epitheca and shorter hypotheca. The surfaces of the main body or capsule is divided by delicate, relatively high, sometimes undulate ledges into five yo six nearly rectangular or trapezoid fields in the epitheca and into an unascertained number of +/- isodiametric fields in the hypotheca; the ledges are supported by small spinules arranged in rows which arise from the surface of the capsule. The membrane which forms the ledges extends apically as a short, hollow, bluntly pointed horn and antapically as a hollow, rounded expansion which, in one example, appears to open terminally. A circle of rather strong spine-like processes is developed at the apical and antapical ends of the capsule. The shell apparently opens by the complete detachment of the apical part including the extreme anterior portion of the capsule.
Dimensions:
type- 97µm long, 42µm broad, capsule 60-32µm.
Range - length 76-108µm, breadth 24-42µm, capsule 48-57µm x20-32µm.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised description:
Stover and Helby, 1987, p. 275:
Description:
Cysts proximate, elongate ellipsoidal, with a short apical horn and generally two, short, rounded or pointed, antapical horns, which may be equal in length, or the right horn may be shorter than the left horn, or absent. Cyst wall punctogranulate and variable in thickness from about 1.5 µm to slightly more than 2 µm.
Archeopyle apical, with principal suture much nearer the apex on the dorsal surface than on the ventral surface. Midventrally, archeopyle margin delimiting parasulcal notch. Small, usually gabled paraplate (Fig. 11A,B) to the left and slightly anterior to the notch, with lateral limits indicated by accessory sutures, with anterior edge marking an inflection along the left ventral archeopyle margin. Corresponding inflection not present along the right ventral margin, where, however, a slight convexity may occur. Operculum free.
Indications of paracingulum or of paratabulation, other than the archeopyle, absent. Anterior extent of a parasulcus inferred solely by parasulcal notch.
Dimensions:
Size range: length 83-108 µm; width 28-51 µm; specimens without opercula 18-27 µm shorter than complete specimens.
Affinities:
In the absence of features clearly denoting paratabulation we cannot confidently identify within the kofoidian system the small paraplate along the left archeopyle margin. Nevertheless, its presence imparts a characteristic asymmetry to the archeopyle margin. This asymmetry is also evident on some specimens of other species assigned to Batioladinium: for example, B. jaegeri (Alberti) Brideaux 1975 (see Brideaux, 1975, fig.3) and of B. longicornutum (Alberti) Brideaux 1975 (see Alberti, 1961, pl.5, fig.21). Brideaux (1975, p. 1241) indicated that the cysts of Batioladinium are somewhat flattened dorsoventrally. This does not appear to be a persistent character of B. micropodum.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Belodinium dysculum Cookson and Eisenack, 1960b, emend. Stover and Helby, 1987d, differs from B.obsoletum and B.asaphum in not having parasutural ornamentation, the latter two species were transferred to Clathroctenocystis by Stover and Helby (1987d) because of this feature. However, Dodekova (1990) retained obsoletum in Belodinium.
Size of Belodinium dysculum: overall without operculum 56-72 µm long, 39-42 µm wide, with operculum specimens are 20-36 µm longer. Processes 3-7 µm long, about 1 µm wide.