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Sumatradinium pustulosum
Sumatradinium pustulosum Lentin et al., 1994
Holotype: Lentin et al., 1994, pl.1, fig.12
Locus typicus: Evangeline H-98 well, Scotian Shelf, offshore eastern Canada
Stratum typicum: Late Miocene (Tortonian)
Original diagnosis: A species of Sumatradinium with uniformly distributed, smooth, round pustules.
Description:
Shape: Cyst weakly to strongly dorsoventrally compressed, ambitus subcircular, suboval, rounded pentagonal to peridinioid. Apex rounded; antapex rounded to weakly bilobate and symmetrical or asymmetrical. Epicyst and hypocyst appear to be more or less equal in size.
Wall relationships: Usually acavate with autophragm only or with endophragm and periphragm appressed; rarely circumcavate, with periphragm and endophragm narrowly separated.
Wall features: Surface ornamentation comprises a complete to incomplete reticulum or, locally, a granulation, in addition to nontabulate, uniformly distributed, smooth, solid or hollow pustules, 2-5 µm in diameter and 1-3 µm high. Pustules rounded to elongate in plan view. Mode of excystment: Archeopyle usually involves the loss of a large hexa sodeltaform middorsal intercalary paraplate, presumably 2a, posteriorly extending almost to the equator of the cyst. The operculum is usually free but may be adnate anteriorly. Rarely, accessory archeopyle sutures develop between paraplates adjacent to 2a and a second intercalary paraplate may be dislodged. When two wall layers are observed, they appear fused on the operculum.
Paratabulation: Generally indicated by archeopyle only and assumed to be peridinialean; occasionally the alignment of processes suggests a paracingulum and possibly other parasutures. Parasulcus not identified.
Size: Holotype: body length 81 µm, body width 83 µm. Range: body length 74(80)84 µm (3 specimens), body width 73(80)84 µm (5 specimens).
Affinities:
Lentin et al., 1994, p.574: The genus Sumatradinium includes four species: S. hispidum (Drugg, 1970) Lentin and Williams, 1976 (the type), S. druggii sp.nov., S. pustulosum sp.nov., and S. soucouyantiae de Verteuil and Norris, 1992. The species can be readily separated by the nature of the processes.
Sumatradinium hispidum has short (up to 5 µm), closed, spine-like processes, which are acuminate distally and commonly penitabulate or possibly sutural. Sumatradinium soucouyantiae has processes 6--20 µm in length, which are usually hollow and distally acuminate to rounded or clavate, not furcate, and always closed. Sumatradinium druggii has processes of variable length and morphology, which usually have annular thickenings and closed furcate terminations. In some processes the "annular thickenings" may be septa but this is impossible to prove under the light microscope. Sumatradinium pustulosum has a low, pustulate ornamentation.
Holotype: Lentin et al., 1994, pl.1, fig.12
Locus typicus: Evangeline H-98 well, Scotian Shelf, offshore eastern Canada
Stratum typicum: Late Miocene (Tortonian)
Original diagnosis: A species of Sumatradinium with uniformly distributed, smooth, round pustules.
Description:
Shape: Cyst weakly to strongly dorsoventrally compressed, ambitus subcircular, suboval, rounded pentagonal to peridinioid. Apex rounded; antapex rounded to weakly bilobate and symmetrical or asymmetrical. Epicyst and hypocyst appear to be more or less equal in size.
Wall relationships: Usually acavate with autophragm only or with endophragm and periphragm appressed; rarely circumcavate, with periphragm and endophragm narrowly separated.
Wall features: Surface ornamentation comprises a complete to incomplete reticulum or, locally, a granulation, in addition to nontabulate, uniformly distributed, smooth, solid or hollow pustules, 2-5 µm in diameter and 1-3 µm high. Pustules rounded to elongate in plan view. Mode of excystment: Archeopyle usually involves the loss of a large hexa sodeltaform middorsal intercalary paraplate, presumably 2a, posteriorly extending almost to the equator of the cyst. The operculum is usually free but may be adnate anteriorly. Rarely, accessory archeopyle sutures develop between paraplates adjacent to 2a and a second intercalary paraplate may be dislodged. When two wall layers are observed, they appear fused on the operculum.
Paratabulation: Generally indicated by archeopyle only and assumed to be peridinialean; occasionally the alignment of processes suggests a paracingulum and possibly other parasutures. Parasulcus not identified.
Size: Holotype: body length 81 µm, body width 83 µm. Range: body length 74(80)84 µm (3 specimens), body width 73(80)84 µm (5 specimens).
Affinities:
Lentin et al., 1994, p.574: The genus Sumatradinium includes four species: S. hispidum (Drugg, 1970) Lentin and Williams, 1976 (the type), S. druggii sp.nov., S. pustulosum sp.nov., and S. soucouyantiae de Verteuil and Norris, 1992. The species can be readily separated by the nature of the processes.
Sumatradinium hispidum has short (up to 5 µm), closed, spine-like processes, which are acuminate distally and commonly penitabulate or possibly sutural. Sumatradinium soucouyantiae has processes 6--20 µm in length, which are usually hollow and distally acuminate to rounded or clavate, not furcate, and always closed. Sumatradinium druggii has processes of variable length and morphology, which usually have annular thickenings and closed furcate terminations. In some processes the "annular thickenings" may be septa but this is impossible to prove under the light microscope. Sumatradinium pustulosum has a low, pustulate ornamentation.