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Palaeocystodinium australinum
Palaeocystodinium australinum (Cookson, 1965b, p.140, pl.25, figs.1–4) Lentin and Williams, 1976, p.89. Emendation: Malloy, 1972, p.63, as Svalbardella australina.
Originally Svalbardella, subsequently (and now) Palaeocystodinium.
Holotype: Cookson, 1965, pl.25, fig.4
Locus typicus: Pebble Point Formation, SW. Victoria
Stratum typicum: Paleocene
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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.
Palaeocystodinium australinum (Cookson, 1965b) Lentin and Williams, 1976, emend. Malloy, 1972, emend. Wrenn and Hart, 1988. Emendation of Wrenn and Hart (1988, p.362): “ Fusiform, dorso-ventrally flattened, cavate dinocysts bearing one long tapering horn at each end of the central body. The apical horn may be distally acuminate, rounded or blunt. The antapical horn bears a short, posteriorly projecting accessory horn or spike along its length or almost distally (but not proximally). The accessory horn occurs on the dinocyst’s right side of the antapical horn. The structurally simple, spindle-shaped endocyst may or may not extend into the pericoels of the horns formed by the pericyst. The endophragm and the periphragm may be closely appressed in the central body area but are separated in the region of the horns. Wall relationship varies from cornucavate to circumcavate. The thin endophragm and periphragm may be smooth to slightly granular. The endophragm may be clear or dark brown in colour, whereas the periphragm is clear. The steno-deltaform intercalary archeopyle is of the I(2a) type and the operculum is free. Paratabulation is absent or poorly developed. Faint suggestions of the location of the parasulcus and paracingulum may be present. The cysts are large and may be more than 250 µm long. Size: length of pericyst 239-302 µm, width 40-61 µm.
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Original description: Cookson, 1965, p.140: Svalbardella australina
Shell fusiform, tapering gradually from an enlarged central portion with convex sides towards both apex and antapex. The left-hand wall of the antapical portion (when the shell is lying with the ventral surface uppermost) narrows suddenly at about 3/4 of its length, in such a way that a small spine-like projection is developed, and then slants towards the pointed apex. The apical portion which terminates in either a bluntish or pointed tip is usually slightly longer than the corresponding antapical portion. The central part of the shell is generally entirely filled with a thin-walled capsule which narrows to varying degrees towards both ends and sometimes extends into the bases of the narrow portions of the shell (Pl. 25, fig. 2). The archeopyle is small, intercalary and basically, though not always distinctly, hexagonal with alternating long and short sides (Pl. 25, fig. 4). A clearly defined tabulation has not been evident; in a few specimens faint indications of an equatorial girdle and faintly outlined areas are present on the dorsal surface (Pl. 25, fig. 1). A large clear area, frequently evident on the ventral surface (Pl. 25, fig. 2) may possibly be related to a longitudinal furrow.
Shell-membrane thin, c. 0.5 µm, smooth in optical section, faintly granular in surface view; wall of capsule finely and closely granular.
Dimensions: Holotype 270 µm long, 54 µm broad. Range 239-302 µm long, 40-61 µm broad.
Emended description: Malloy, 1972, p. 63: Svarbadella australina
Proposed emended description: Cyst fusiform in external outline, composed of a thin-walled outer cyst and an inner cyst whose wall may be thick and dark brown in color, or thin and nearly colorless. Externally, the apical and antapical horns narrow markedly over the ends of the oval inner cyst and display either acute or blunted tips. The apical is a single elongate horn, simple in structure, while the antapical horn may have a minute downward-pointing secondary projection tangential on its side or a thin short "spur" which projects from the periphragm near the horn's basal (proximal) contact. Lengths of the apical and antapical horns are equal to 1/2 to 1/3 that of the inner cyst. The structure of the apical and antapical portions of the inner cyst appears complex (Text-fig. 2 ), with an inner projection often filling the horn and tightly enclosed by the periphragm. This interior portion of the horn is attached basally at an area of thickening which forms a "boss" on the inner capsule.
The archeopyle is simple, hexagonal and intercalary with alternating long and short margins and a detached operculum. The surface of the periphragm is smooth and indications of tabulation are absent. Examination of several specimens using phase and Nomarski interference illumination gave no clear indications of tabulation or girdle or sulcal areas. The inner cyst wall is smooth to finely but irregularly granulose. A median transverse fold is often present on the cyst, expressed in both periphragm and endophragm, and may be the indirect reflection of a girdle.
Originally Svalbardella, subsequently (and now) Palaeocystodinium.
Holotype: Cookson, 1965, pl.25, fig.4
Locus typicus: Pebble Point Formation, SW. Victoria
Stratum typicum: Paleocene
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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.
Palaeocystodinium australinum (Cookson, 1965b) Lentin and Williams, 1976, emend. Malloy, 1972, emend. Wrenn and Hart, 1988. Emendation of Wrenn and Hart (1988, p.362): “ Fusiform, dorso-ventrally flattened, cavate dinocysts bearing one long tapering horn at each end of the central body. The apical horn may be distally acuminate, rounded or blunt. The antapical horn bears a short, posteriorly projecting accessory horn or spike along its length or almost distally (but not proximally). The accessory horn occurs on the dinocyst’s right side of the antapical horn. The structurally simple, spindle-shaped endocyst may or may not extend into the pericoels of the horns formed by the pericyst. The endophragm and the periphragm may be closely appressed in the central body area but are separated in the region of the horns. Wall relationship varies from cornucavate to circumcavate. The thin endophragm and periphragm may be smooth to slightly granular. The endophragm may be clear or dark brown in colour, whereas the periphragm is clear. The steno-deltaform intercalary archeopyle is of the I(2a) type and the operculum is free. Paratabulation is absent or poorly developed. Faint suggestions of the location of the parasulcus and paracingulum may be present. The cysts are large and may be more than 250 µm long. Size: length of pericyst 239-302 µm, width 40-61 µm.
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Original description: Cookson, 1965, p.140: Svalbardella australina
Shell fusiform, tapering gradually from an enlarged central portion with convex sides towards both apex and antapex. The left-hand wall of the antapical portion (when the shell is lying with the ventral surface uppermost) narrows suddenly at about 3/4 of its length, in such a way that a small spine-like projection is developed, and then slants towards the pointed apex. The apical portion which terminates in either a bluntish or pointed tip is usually slightly longer than the corresponding antapical portion. The central part of the shell is generally entirely filled with a thin-walled capsule which narrows to varying degrees towards both ends and sometimes extends into the bases of the narrow portions of the shell (Pl. 25, fig. 2). The archeopyle is small, intercalary and basically, though not always distinctly, hexagonal with alternating long and short sides (Pl. 25, fig. 4). A clearly defined tabulation has not been evident; in a few specimens faint indications of an equatorial girdle and faintly outlined areas are present on the dorsal surface (Pl. 25, fig. 1). A large clear area, frequently evident on the ventral surface (Pl. 25, fig. 2) may possibly be related to a longitudinal furrow.
Shell-membrane thin, c. 0.5 µm, smooth in optical section, faintly granular in surface view; wall of capsule finely and closely granular.
Dimensions: Holotype 270 µm long, 54 µm broad. Range 239-302 µm long, 40-61 µm broad.
Emended description: Malloy, 1972, p. 63: Svarbadella australina
Proposed emended description: Cyst fusiform in external outline, composed of a thin-walled outer cyst and an inner cyst whose wall may be thick and dark brown in color, or thin and nearly colorless. Externally, the apical and antapical horns narrow markedly over the ends of the oval inner cyst and display either acute or blunted tips. The apical is a single elongate horn, simple in structure, while the antapical horn may have a minute downward-pointing secondary projection tangential on its side or a thin short "spur" which projects from the periphragm near the horn's basal (proximal) contact. Lengths of the apical and antapical horns are equal to 1/2 to 1/3 that of the inner cyst. The structure of the apical and antapical portions of the inner cyst appears complex (Text-fig. 2 ), with an inner projection often filling the horn and tightly enclosed by the periphragm. This interior portion of the horn is attached basally at an area of thickening which forms a "boss" on the inner capsule.
The archeopyle is simple, hexagonal and intercalary with alternating long and short margins and a detached operculum. The surface of the periphragm is smooth and indications of tabulation are absent. Examination of several specimens using phase and Nomarski interference illumination gave no clear indications of tabulation or girdle or sulcal areas. The inner cyst wall is smooth to finely but irregularly granulose. A median transverse fold is often present on the cyst, expressed in both periphragm and endophragm, and may be the indirect reflection of a girdle.