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Sumatradinium soucouyantae
Sumatradinium soucouyantae de Verteuil and Norris, 1992
Holotype: de Verteuil and Norris, 1992, pl.8, figs.1-2
Locus typicus: Randle Cliff, Chesapeake Bay, Calvert County, Maryland, U.S.A.
Stratum typicum: Middle Miocene
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Sumatradinium soucouyantiae de Verteuil and Norris, 1992. According to de Verteuil and Norris (1992, p.402), Sumatradinium soucouyantiae is dorso-ventrally compressed with a rounded subcircular outline and with numerous intratabular to nontabular hollow processes. The processes are usually between 10% and 20% of equatorial diameter in length and are typically evexate or bulbous. Usually one to four processes per specimen are branched at about two-thirds of their length. Processes are distributed throughout the cyst but tend to be concentrated on the ambitus. The processes are 6-20 µm long. Size: mid-body length without processes 65-90 µm, equatorial diameter 64-85 µm, process length 6-15 µm.
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Original diagnosis: de Verteuil and Norris, 1992, p. 402, 404
A species of Sumatradinium that is dorsoventrally compressed with a rounded, sub
circular outline and characterized by its many intratabular to nontabular, hollow processes. These are predominantly between 10% and 20% of equatorial diameter in length and are typically evexate or bulbous. Usually, one to four processes per specimen are branched at about two thirds of their length in a symmetrical bifurcation that has closed distal terminations. Processes are distributed throughout the cyst surface but appear concentrated about the ambitus of compressed specimens. The archeopyle is 2a intercalary, latideltaform, operculum free. Cingulum and sulcus are usually obscure.
Original description: de Verteuil and Norris, 1992, p. 404
The cyst is dorsoventrally compressed and rounded-pentagonal to circular in outline; it is widest above the cingulum, between the anterior and posterior margins or the archeopyle. The cingulum is therefore suppressed and in most specimens cannot be determined. The epicyst is convex with a gently rounded apex and is larger than the hypocyst.
The wall is made up of two layers: a fenestrate endophragm and a reticulate periphragm, of which the sheath-like processes are a part. The nanno-fenestrations in the endophragm (which is approximately 0.5 µm thick and otherwise psilate) are 0.2-0.5 µm in diameter and form a reticulate pattern that directly underlies the positive elements of the periphragmal reticulum. Larger fenestrations, approximately 2 µm in diameter, occur in the endophragm directly beneath each process base. These holes are surrounded by a ring of about 10 smaller holes that are 0.2-0.5 µm in diameter. The periphragm, excluding the processes, consists of a thin wall in contact with a fused, irregular, network reticulum of round, elongate strands with a cross-sectional diameter of 0.2 µm and an uneven nannopustulose surface. The lumina are between 1 µm and 2 µm wide and irregular in shape. The overall coarseness of the reticulum may vary a little among specimens but is fairly constant.
The processes are psilate, hollow, tapered or evexate sheaths. They are proximally open and arise from the reticulate periphragm; being surrounded by radially elongate lumina, they appear to exert the main control for the pattern of the reticulum. There is sometimes a distinctive apical process made up of two processes fused proximally and along most of their lengths. The processes and reticulum are negatively mirrored by the fenestrations of the endophragm. The two wall layers are connected by minute strands whose topologic relation to the holes in the endophragm is not clear (Plate 12, fig. 6). The hexa intercalary archeopyle gives the only indication of tabulation. The cyst wall has been observed both with and without pigmentation.
Dimensions. Mid-body length without processes, 65(79)90 µm; holotype, 87 µm. Equatorial diameter, 64(74)85 µm; holotype 75 µm. Processes, 6-15 µm. Fifteen specimens measured.
Affinities:
de Verteuil and Norris, 1992, p. 404: The new species is most similar to Sumatradinium hispidum (Drugg 1970) Lentin & Williams 1976 from which it differs in having consistently longer processes. In addition, specimens of S. hispidum, including the holotype, commonly develop pericoels between the endocyst and pericyst (Judith Lentin, oral commun. to LV, 1989).
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. Specimens of S. soucouyantae are common in the Middle-Late Miocene samples from Evangeline H-98 well. The Scotian Shelf specimens show some differences from the type material as described by de Verteuil and Norris (1992). The surface ornamentation varies from a complete or incomplete irregular reticulum to, locally, an irregular granulation; the latter may be an artifact of preservation. The specimens reported by de Verteuil and Norris have processes 6-15 µm in length; the Scotian Shelf specimens have processes up to 20 µm in length.
Holotype: de Verteuil and Norris, 1992, pl.8, figs.1-2
Locus typicus: Randle Cliff, Chesapeake Bay, Calvert County, Maryland, U.S.A.
Stratum typicum: Middle Miocene
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Sumatradinium soucouyantiae de Verteuil and Norris, 1992. According to de Verteuil and Norris (1992, p.402), Sumatradinium soucouyantiae is dorso-ventrally compressed with a rounded subcircular outline and with numerous intratabular to nontabular hollow processes. The processes are usually between 10% and 20% of equatorial diameter in length and are typically evexate or bulbous. Usually one to four processes per specimen are branched at about two-thirds of their length. Processes are distributed throughout the cyst but tend to be concentrated on the ambitus. The processes are 6-20 µm long. Size: mid-body length without processes 65-90 µm, equatorial diameter 64-85 µm, process length 6-15 µm.
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Original diagnosis: de Verteuil and Norris, 1992, p. 402, 404
A species of Sumatradinium that is dorsoventrally compressed with a rounded, sub
circular outline and characterized by its many intratabular to nontabular, hollow processes. These are predominantly between 10% and 20% of equatorial diameter in length and are typically evexate or bulbous. Usually, one to four processes per specimen are branched at about two thirds of their length in a symmetrical bifurcation that has closed distal terminations. Processes are distributed throughout the cyst surface but appear concentrated about the ambitus of compressed specimens. The archeopyle is 2a intercalary, latideltaform, operculum free. Cingulum and sulcus are usually obscure.
Original description: de Verteuil and Norris, 1992, p. 404
The cyst is dorsoventrally compressed and rounded-pentagonal to circular in outline; it is widest above the cingulum, between the anterior and posterior margins or the archeopyle. The cingulum is therefore suppressed and in most specimens cannot be determined. The epicyst is convex with a gently rounded apex and is larger than the hypocyst.
The wall is made up of two layers: a fenestrate endophragm and a reticulate periphragm, of which the sheath-like processes are a part. The nanno-fenestrations in the endophragm (which is approximately 0.5 µm thick and otherwise psilate) are 0.2-0.5 µm in diameter and form a reticulate pattern that directly underlies the positive elements of the periphragmal reticulum. Larger fenestrations, approximately 2 µm in diameter, occur in the endophragm directly beneath each process base. These holes are surrounded by a ring of about 10 smaller holes that are 0.2-0.5 µm in diameter. The periphragm, excluding the processes, consists of a thin wall in contact with a fused, irregular, network reticulum of round, elongate strands with a cross-sectional diameter of 0.2 µm and an uneven nannopustulose surface. The lumina are between 1 µm and 2 µm wide and irregular in shape. The overall coarseness of the reticulum may vary a little among specimens but is fairly constant.
The processes are psilate, hollow, tapered or evexate sheaths. They are proximally open and arise from the reticulate periphragm; being surrounded by radially elongate lumina, they appear to exert the main control for the pattern of the reticulum. There is sometimes a distinctive apical process made up of two processes fused proximally and along most of their lengths. The processes and reticulum are negatively mirrored by the fenestrations of the endophragm. The two wall layers are connected by minute strands whose topologic relation to the holes in the endophragm is not clear (Plate 12, fig. 6). The hexa intercalary archeopyle gives the only indication of tabulation. The cyst wall has been observed both with and without pigmentation.
Dimensions. Mid-body length without processes, 65(79)90 µm; holotype, 87 µm. Equatorial diameter, 64(74)85 µm; holotype 75 µm. Processes, 6-15 µm. Fifteen specimens measured.
Affinities:
de Verteuil and Norris, 1992, p. 404: The new species is most similar to Sumatradinium hispidum (Drugg 1970) Lentin & Williams 1976 from which it differs in having consistently longer processes. In addition, specimens of S. hispidum, including the holotype, commonly develop pericoels between the endocyst and pericyst (Judith Lentin, oral commun. to LV, 1989).
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. Specimens of S. soucouyantae are common in the Middle-Late Miocene samples from Evangeline H-98 well. The Scotian Shelf specimens show some differences from the type material as described by de Verteuil and Norris (1992). The surface ornamentation varies from a complete or incomplete irregular reticulum to, locally, an irregular granulation; the latter may be an artifact of preservation. The specimens reported by de Verteuil and Norris have processes 6-15 µm in length; the Scotian Shelf specimens have processes up to 20 µm in length.