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Distatodinium biffii
Distatodinium biffii Brinkhuis et al., 1992, p.238,240, pl.3, figs.1-4; pl.6, fig.4; pl.9, fig.4.
Brinkhuis et al. (1992, p.238) considered Microsphaeridium ancistroides to be the possible taxonomic senior synonym of this species.
Holotype: Brinkhuis et al., 1992, pl.3, figs.1-4.
Locus typicus: Contessa Quarry Section, Marche Basin, Italy
Age: latest Oligocene.
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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.
Distatodinium biffii Brinkhuis et al., 1992, is characterized by the lack of processes in the medial area. Processes are tubiform, hollow, with extremely broad bases and wide or slender shafts: distally they are always complexly branched. The processes are restricted to the posterior and anterior parts of the cyst and are probably intratabular. As well as the apical and antapical paraplate series, the processes also occupy the posterior parts of the postcingular series and the anterior parts of the precingular series. The holotype has seven processes around the archeopyle margin. Four processes are on the hypocyst, possibly reflecting the antapical, 4"’, posterior intercalary and posterior sulcal paraplates. Surface ornament smooth to faintly granulate. Size: length 68-121 µm, width, 35-63 µm.
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Original diagnosis: Brinkhuis et al., 1992, p.238
A species of Distatodinium that is characterized by the absence of processes in the medial area. Processes are tubiform, hollow, with extremely broad bases and wide or slender shafts; distally they are always complexly branched. The processes are restricted to the posterior and anterior parts of the cyst body and adopt probable intratabular positions. As well as the apical and antapical paraplate series, the processes also occupy the posterior parts of the postcingular series and the anterior parts of the precingular series. The holotype exhibits seven processes around the archeopyle margin (Plate 3, figs. 1-4), possibly representing the precingular paraplates and one sulcal paraplate. Four processes are present on the hypocyst possibly reflecting the antapical, posterior intercalary and posterior sulcal paraplates. The surface ornament is smooth to faintly granulate, rarely showing signs of a punctate nature.
Dimensions. Central body length: 68-121 Ám (holotype, 95 Ám); width: 35-63 Ám (holotype, 52 Ám). Process length: 28-65 Ám (holotype, 45-55 Ám).
Affinities:
Brinkhuis et al., 1992, p.240
Morphotypes similar to Distatodinium biffii co-occur with D. biffii in Oligocene sediments from the North- and Norwegian Sea basins (pers. obs., present authors). These differ from D. biffii in possessing isolated processes within the broad medial zone, and they may constitute at least one species distinct from D. biffii.
Although Biffi and Manum (1988) observed this taxon in their material, they did not establish a new species because there was an insufficient number of specimens available to them. Instead, they referred to this dinoflagellate cyst as "Distatodinium paradoxum (Brosius 1963) Eaton 1976 sensu Gocht 1969". On this basis, it could be argued that D. biffii represents an end member within the specific variation of D. paradoxum. However, we consider that the very distinctive wide medial area and the extremely large size of D. biffii are sufficiently consistent characteristics for it to be used as a criterion for specific differentiation.
The processes of D. biffii are similar to those of the holotype of the monotypic genus Microsphaeridium Benedek 1972. Although Stover and Evitt (1978, p. 295) considered Microsphaeridium to be an acritarch genus, Benedek and Sarjeant (1981, p. 344, 346) were confident that the type material represents the detached opercula of skolochorate dinoflagellate cysts. On this basis, Benedek and Sarjeant (1981, p. 347) argued that if "... the holotype represents the operculum of an undescribed species, then it is likely to retain its validity [and] since the morphology of the complete cyst from which this operculum was derived is not known ... we recommend that, for the moment, usage of this species name be restricted to the holotype". Benedek and Sarjeant (1981) also realized that the type material consists of the opercula of two or three different species. From the available illustrations it seems plausible that the holotype of Microsphaeridium ancistroides Benedek 1972 is in fact an operculum of a species referable to the genus Distatodinium, and possibly D. biffii as inferred by Head and Norris (1989, p. 529, for Distatodinium paradoxum [Brosius] Eaton sensu Gocht, 1969). On the same basis, paratype 771/ 152, as illustrated by Benedek and Sarjeant (1981, fig. 2.5), could possibly be the operculum of Distatodinium paradoxum (Brosius 1963) Eaton 1976. However, Benedek (1972) neither described nor illustrated a complete specimen which could be assigned to the genus Distatodinium, although he did record D. paradoxum (as Tanyosphaeridium paradoxum). Because these relationships remain equivocal, we suggest that usage of Microsphaeridium should remain restricted to the type material. Head and Norris (1989) reached similar conclusions with regard to this genus.
Brinkhuis et al. (1992, p.238) considered Microsphaeridium ancistroides to be the possible taxonomic senior synonym of this species.
Holotype: Brinkhuis et al., 1992, pl.3, figs.1-4.
Locus typicus: Contessa Quarry Section, Marche Basin, Italy
Age: latest Oligocene.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Distatodinium biffii Brinkhuis et al., 1992, is characterized by the lack of processes in the medial area. Processes are tubiform, hollow, with extremely broad bases and wide or slender shafts: distally they are always complexly branched. The processes are restricted to the posterior and anterior parts of the cyst and are probably intratabular. As well as the apical and antapical paraplate series, the processes also occupy the posterior parts of the postcingular series and the anterior parts of the precingular series. The holotype has seven processes around the archeopyle margin. Four processes are on the hypocyst, possibly reflecting the antapical, 4"’, posterior intercalary and posterior sulcal paraplates. Surface ornament smooth to faintly granulate. Size: length 68-121 µm, width, 35-63 µm.
--------------------------------------------------
Original diagnosis: Brinkhuis et al., 1992, p.238
A species of Distatodinium that is characterized by the absence of processes in the medial area. Processes are tubiform, hollow, with extremely broad bases and wide or slender shafts; distally they are always complexly branched. The processes are restricted to the posterior and anterior parts of the cyst body and adopt probable intratabular positions. As well as the apical and antapical paraplate series, the processes also occupy the posterior parts of the postcingular series and the anterior parts of the precingular series. The holotype exhibits seven processes around the archeopyle margin (Plate 3, figs. 1-4), possibly representing the precingular paraplates and one sulcal paraplate. Four processes are present on the hypocyst possibly reflecting the antapical, posterior intercalary and posterior sulcal paraplates. The surface ornament is smooth to faintly granulate, rarely showing signs of a punctate nature.
Dimensions. Central body length: 68-121 Ám (holotype, 95 Ám); width: 35-63 Ám (holotype, 52 Ám). Process length: 28-65 Ám (holotype, 45-55 Ám).
Affinities:
Brinkhuis et al., 1992, p.240
Morphotypes similar to Distatodinium biffii co-occur with D. biffii in Oligocene sediments from the North- and Norwegian Sea basins (pers. obs., present authors). These differ from D. biffii in possessing isolated processes within the broad medial zone, and they may constitute at least one species distinct from D. biffii.
Although Biffi and Manum (1988) observed this taxon in their material, they did not establish a new species because there was an insufficient number of specimens available to them. Instead, they referred to this dinoflagellate cyst as "Distatodinium paradoxum (Brosius 1963) Eaton 1976 sensu Gocht 1969". On this basis, it could be argued that D. biffii represents an end member within the specific variation of D. paradoxum. However, we consider that the very distinctive wide medial area and the extremely large size of D. biffii are sufficiently consistent characteristics for it to be used as a criterion for specific differentiation.
The processes of D. biffii are similar to those of the holotype of the monotypic genus Microsphaeridium Benedek 1972. Although Stover and Evitt (1978, p. 295) considered Microsphaeridium to be an acritarch genus, Benedek and Sarjeant (1981, p. 344, 346) were confident that the type material represents the detached opercula of skolochorate dinoflagellate cysts. On this basis, Benedek and Sarjeant (1981, p. 347) argued that if "... the holotype represents the operculum of an undescribed species, then it is likely to retain its validity [and] since the morphology of the complete cyst from which this operculum was derived is not known ... we recommend that, for the moment, usage of this species name be restricted to the holotype". Benedek and Sarjeant (1981) also realized that the type material consists of the opercula of two or three different species. From the available illustrations it seems plausible that the holotype of Microsphaeridium ancistroides Benedek 1972 is in fact an operculum of a species referable to the genus Distatodinium, and possibly D. biffii as inferred by Head and Norris (1989, p. 529, for Distatodinium paradoxum [Brosius] Eaton sensu Gocht, 1969). On the same basis, paratype 771/ 152, as illustrated by Benedek and Sarjeant (1981, fig. 2.5), could possibly be the operculum of Distatodinium paradoxum (Brosius 1963) Eaton 1976. However, Benedek (1972) neither described nor illustrated a complete specimen which could be assigned to the genus Distatodinium, although he did record D. paradoxum (as Tanyosphaeridium paradoxum). Because these relationships remain equivocal, we suggest that usage of Microsphaeridium should remain restricted to the type material. Head and Norris (1989) reached similar conclusions with regard to this genus.