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Glossodinium dimorphum
Glossodinium dimorhpum Ioannides et al., 1977; emend. Courtinat in Courtinat and Gaillard, 1980
Originally (and now) Glossodinium, subsequently Dinopterygium.
Drugg, 1978, transferred this species to Dinopterygium Deflandre, 1935. Courtinat in Courtinat and Gaillard, 1980, retained it in Glossodinium. Courtinat, 1989, agreed with Drugg, 1978. Poulsen, 1992, agreed with Courtinat in Courtinat and Gaillard, 1980.
Holotype: Ioannides et al., 1977, pl. 2, fig. 13
Locus typicus: Clavel's Hard, Dorset, England
Stratum typicum: Kimmeridgian
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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.
Glossodinium dimorphum Ioannides et al., 1977, is divided by a cingular zone into epi- and hypocyst of approximately equal size. Epicyst terminates in a rounded to truncate apical horn. Periphragm folded showing pseudoreticulate pattern. Periphragm distally developed into complex antapical structure composed of 2-6, but usually 3-4 digitations. Cingulum bordered by thin membranous crests bearing thickenings (folds) more or less radially disposed. Size: overall length 94-135 µm, width 90-117 µm, capsule length 69-97 µm, cingular crests 8-17 µm high, length of antapical prominence 17-30 µm.
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Original description: Ioannides et al., 1977, p. 453
Diagnosis (that of the genus, Ioannides et al., 1977, p. 452): Cyst two-layered; in dorsal or ventral view subrhombohedral in outline; in apical or antapical view more or less circular. Epitract and hypotract of approximately equal size. Periphragm thin, finely folded, often in pseudoreticulate fashion. Periphragm ending in stout apical horn; distally, developing into complex prominence composed of a number of digitations of variable size. Cingulum well developed, bordered by membranous crests bearing radial striations (folds). In apical or antapical view, cingular crests appear invaginated toward sulcal zone, thereby indicating position of sulcus. Inner body large, normally closely appressed to periphragm except for apical and, rarely antapical regions. Tabulation not observed. Precingular archaeopyle occasionally occurs.
Description (annotated): Cyst two-layered; circular to slightly compressed dorsoventrally, more or less circular in apical or antapical orientation. Epitract terminates in a rounded to truncate stout horn, sometimes irregular in shape. Periphragm thin and transparent invariably folded giving rise to fine linear striations, in places or on entire surface, often assuming pseudoreticulate pattern. Periphragm distally developing into complex antapical structure composed of 2-6, but usually 3-4 digitations. In apical or antapical view, cingular crests encircle cyst except at sulcal region for about 12 Ám, where crests invaginate toward sulcal borders; in same view cingular crests show parallel-edged appearance. Inner body large, thin-walled, in close contact with periphragm, completely filling pericoel except in apical and rarely in antapical regions. Endophragm occasionally forming short apical protuberance but antapex, when observed, is rounded. Tabulation apperently absent but in rare cases some plates may be simulated by arrangements of folds. Precingular archaeopyle occasionally occurs, corresponding to position of plate 3''. Dimensions: Range: overall length 94-135 Ám, breadth 90-117 Ám; capsule length 69-97 Ám; cingular crests 8-17 Ám high; length of antapical prominence 17-30 Ám (36 specimens measured).
Emended diagnosis: Courtinat in Courtinat and Gaillard, 1980, p. 32
Cyst bicavate, circular to slightly dorsoventrally compressed, more or less circular in polar view. Outline subrhomboedrical in ventral or dorsal view. Paracingulum dividing the cyst into epiphragma and hypophragma of approximately equal size. Epiperiphragm, thin and transparent, abundantly folded, terminates in an apical protruberance. Hypoperiphragm producing digitations in the antapical region. Paracingulum very strongly indicated by membranous crests. Endophragm large with thin wall, closely connected to the periphragm by means of pillars. Tabulation formula 4', 6'', 5''', 1p, 1''''. Combination archaeopyle, type (tA(a))+3P.
Description: Form: see diagnosis. Special features: Parasutures indicated by thin and membranous crests. Plate 1'''' roughly pentagonal, possessing one or more large digitation at each of its corners. The parasutural crest bordering this paraplate is entirely digatated in the intergonal region. Latter digitations are small, of constant size and regularly spaced.
Paratabulation: Indicated by membranous parasutures and archaeopyle.
Paracingulum: Paracingular crest bordering the lower epiperiphragm to that bordering the hypoperiphragm. The crests invaginate in the parasulcal region.
Parasulcus: Long and straight, extending over the entire length of the cyst.
Dimensions: Total length 75-91 µm, total width 75-81 µm, length of enddophragm 50-68 µm, width of enddophragm 52-56 µm. 26 specimens measured.
Affinities: Ioannides et al., 1977, p. 453
The specimen figured by Downie (1957, pl. 20, fig. 2) as Palaeoperidinium bicuneatum Deflandre, 1938, was examined by the present authors, and the antapical, distally digitate, prominence was observed. This morphographical character renders Glossodinium dimorphum highly distinctive. In our opinion, the holotype ?Glossodinium bicuneatum Deflandre, 1938 (p. 180, pl. 8, fig. 7) (specimen in inverse orientation), is different from G. dimorphum. Deflandre's species was erected on the basis of single specimen which was in a poor state of preservation, and its detail structure has never been clarified. Nevertheless, it can be clearly seen that it lacks the digitate distal process, whereas the position ot its archaeopyle is unknown. The holotype of ?G. bicuneatum was subsequently examined by J.P. Verdier (personal communication) and a phase contrast photograph was seen by one of us (N.S. Ioannides). The difference between ?G. bicuneatum and G. dimorphum was thus confirmed. Consequently, it is here desireable to allocate Delfandre's species in the genus Glossodinium because of its similar gross morphography, but only tentatively because of its uncertain detail structure. All subsequently described forms bearing the digitate distal process are included in G. dimorphum.
Originally (and now) Glossodinium, subsequently Dinopterygium.
Drugg, 1978, transferred this species to Dinopterygium Deflandre, 1935. Courtinat in Courtinat and Gaillard, 1980, retained it in Glossodinium. Courtinat, 1989, agreed with Drugg, 1978. Poulsen, 1992, agreed with Courtinat in Courtinat and Gaillard, 1980.
Holotype: Ioannides et al., 1977, pl. 2, fig. 13
Locus typicus: Clavel's Hard, Dorset, England
Stratum typicum: Kimmeridgian
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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.
Glossodinium dimorphum Ioannides et al., 1977, is divided by a cingular zone into epi- and hypocyst of approximately equal size. Epicyst terminates in a rounded to truncate apical horn. Periphragm folded showing pseudoreticulate pattern. Periphragm distally developed into complex antapical structure composed of 2-6, but usually 3-4 digitations. Cingulum bordered by thin membranous crests bearing thickenings (folds) more or less radially disposed. Size: overall length 94-135 µm, width 90-117 µm, capsule length 69-97 µm, cingular crests 8-17 µm high, length of antapical prominence 17-30 µm.
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Original description: Ioannides et al., 1977, p. 453
Diagnosis (that of the genus, Ioannides et al., 1977, p. 452): Cyst two-layered; in dorsal or ventral view subrhombohedral in outline; in apical or antapical view more or less circular. Epitract and hypotract of approximately equal size. Periphragm thin, finely folded, often in pseudoreticulate fashion. Periphragm ending in stout apical horn; distally, developing into complex prominence composed of a number of digitations of variable size. Cingulum well developed, bordered by membranous crests bearing radial striations (folds). In apical or antapical view, cingular crests appear invaginated toward sulcal zone, thereby indicating position of sulcus. Inner body large, normally closely appressed to periphragm except for apical and, rarely antapical regions. Tabulation not observed. Precingular archaeopyle occasionally occurs.
Description (annotated): Cyst two-layered; circular to slightly compressed dorsoventrally, more or less circular in apical or antapical orientation. Epitract terminates in a rounded to truncate stout horn, sometimes irregular in shape. Periphragm thin and transparent invariably folded giving rise to fine linear striations, in places or on entire surface, often assuming pseudoreticulate pattern. Periphragm distally developing into complex antapical structure composed of 2-6, but usually 3-4 digitations. In apical or antapical view, cingular crests encircle cyst except at sulcal region for about 12 Ám, where crests invaginate toward sulcal borders; in same view cingular crests show parallel-edged appearance. Inner body large, thin-walled, in close contact with periphragm, completely filling pericoel except in apical and rarely in antapical regions. Endophragm occasionally forming short apical protuberance but antapex, when observed, is rounded. Tabulation apperently absent but in rare cases some plates may be simulated by arrangements of folds. Precingular archaeopyle occasionally occurs, corresponding to position of plate 3''. Dimensions: Range: overall length 94-135 Ám, breadth 90-117 Ám; capsule length 69-97 Ám; cingular crests 8-17 Ám high; length of antapical prominence 17-30 Ám (36 specimens measured).
Emended diagnosis: Courtinat in Courtinat and Gaillard, 1980, p. 32
Cyst bicavate, circular to slightly dorsoventrally compressed, more or less circular in polar view. Outline subrhomboedrical in ventral or dorsal view. Paracingulum dividing the cyst into epiphragma and hypophragma of approximately equal size. Epiperiphragm, thin and transparent, abundantly folded, terminates in an apical protruberance. Hypoperiphragm producing digitations in the antapical region. Paracingulum very strongly indicated by membranous crests. Endophragm large with thin wall, closely connected to the periphragm by means of pillars. Tabulation formula 4', 6'', 5''', 1p, 1''''. Combination archaeopyle, type (tA(a))+3P.
Description: Form: see diagnosis. Special features: Parasutures indicated by thin and membranous crests. Plate 1'''' roughly pentagonal, possessing one or more large digitation at each of its corners. The parasutural crest bordering this paraplate is entirely digatated in the intergonal region. Latter digitations are small, of constant size and regularly spaced.
Paratabulation: Indicated by membranous parasutures and archaeopyle.
Paracingulum: Paracingular crest bordering the lower epiperiphragm to that bordering the hypoperiphragm. The crests invaginate in the parasulcal region.
Parasulcus: Long and straight, extending over the entire length of the cyst.
Dimensions: Total length 75-91 µm, total width 75-81 µm, length of enddophragm 50-68 µm, width of enddophragm 52-56 µm. 26 specimens measured.
Affinities: Ioannides et al., 1977, p. 453
The specimen figured by Downie (1957, pl. 20, fig. 2) as Palaeoperidinium bicuneatum Deflandre, 1938, was examined by the present authors, and the antapical, distally digitate, prominence was observed. This morphographical character renders Glossodinium dimorphum highly distinctive. In our opinion, the holotype ?Glossodinium bicuneatum Deflandre, 1938 (p. 180, pl. 8, fig. 7) (specimen in inverse orientation), is different from G. dimorphum. Deflandre's species was erected on the basis of single specimen which was in a poor state of preservation, and its detail structure has never been clarified. Nevertheless, it can be clearly seen that it lacks the digitate distal process, whereas the position ot its archaeopyle is unknown. The holotype of ?G. bicuneatum was subsequently examined by J.P. Verdier (personal communication) and a phase contrast photograph was seen by one of us (N.S. Ioannides). The difference between ?G. bicuneatum and G. dimorphum was thus confirmed. Consequently, it is here desireable to allocate Delfandre's species in the genus Glossodinium because of its similar gross morphography, but only tentatively because of its uncertain detail structure. All subsequently described forms bearing the digitate distal process are included in G. dimorphum.