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Barssidinium wrennii
Barssidinium wrennii, Lentin et al., 1994
Taxonomic senior synonym: Barssidinium pliocenicum, according to De Schepper et al. (2004, p.634).
Holotype: Lentin et al., 1994, pl.2, figs.2, 5
Paratypes: Lentin et al., 1994, pl.2, figs.4, 6
Locus typicus: Evangeline H-98 well, Scotian Shelf
Stratum typicum: Pliocene
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Original description: [Lentin et al., 1994, p. 578]:
Diagnosis:
A species of Barssidinium with processes that are hollow, thin, tapering, and generally closed and furcate distally. Process length about one sixth to one eighth of the length of the central body.
Description:
Shape: Cyst outline tends to be rounded pentagonal to peridinioid. Cyst weakly to strongly dorsoventrally compressed, ambitus subcircular, suboval, rounded pentagonal to peridinioid. Apex rounded; antapex rounded to weakly bilobate. Epicyst and hypocyst appear to be more or less equal in size.
Wall relationships: Usually acavate with autophragm only; rarely circumcavate, with periphragm and endophragm narrowly separated.
Wall features: Periphragm or autophragm smooth to granulate. Processes are concentrated marginally and may show alignment; they are hollow, thin, tapering, distally expanded, sometimes with a subterminal constriction, and generally closed and furcate. Processes occasionally bifurcate. Process length about one sixth to one eighth of the length of the central body and with a length-to-breadth ratio of about 6:1. Processes may have annular thickenings (or septa).
Mode of excystment: Usually involves the loss of a large hexa isodeltaform 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 between paraplates adjacent to 2a appear to develop 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 presumed to be peridinialean; occasional alignment of processes suggests a paracingulum and possibly other parasutures. Parasulcus not identified.
Dimensions/Size:
Holotype: body length 88 µm, body width 57 µm, maximum length of processes 17 µm.
Range: body length 66(87)114 µm (26 specimens), body width 56(75)96 µm (26 specimens), minimum length of processes 6(10)14 µm (20 specimens), maximum length of processes 9(14)22 µm (26 specimens).
Affinities:
Barssidinium wrennii, Barssidinium evangelineae, and Barssidinium graminosum are differentiated on the basis of the processes. Both B. wrennii and B. graminosum differ from B. evangelineae in having distally closed, furcate processes, in contrast to the distally open, aculeate processes of B. evangelineae. The length of the processes in B. wrennii and B. graminosum is different: in B. wrennii the process length is about one sixth to one eighth of the length of the central body; in B. graminosum, the process length is about one third to one fifth of the length of the central body. Although the process length in B. evangelineae is typically shorter than that in B. wrennii, there is some overlap.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Barssidinium wrennii Lentin et al., 1994, has hollow, thin, tapering processes that are generally closed and furcate distally. Process length about 1/6 to 1/8th of length of central body. Barssidinium graminosum has processes that are 1/5th to 1/3rd the length of the central body.
Size: body length 68-114 µm, width 56-96 µm. Minimum length of processes 6-14 µm, maximum length of processes 9-22 µm.
Taxonomic senior synonym: Barssidinium pliocenicum, according to De Schepper et al. (2004, p.634).
Holotype: Lentin et al., 1994, pl.2, figs.2, 5
Paratypes: Lentin et al., 1994, pl.2, figs.4, 6
Locus typicus: Evangeline H-98 well, Scotian Shelf
Stratum typicum: Pliocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Lentin et al., 1994, p. 578]:
Diagnosis:
A species of Barssidinium with processes that are hollow, thin, tapering, and generally closed and furcate distally. Process length about one sixth to one eighth of the length of the central body.
Description:
Shape: Cyst outline tends to be rounded pentagonal to peridinioid. Cyst weakly to strongly dorsoventrally compressed, ambitus subcircular, suboval, rounded pentagonal to peridinioid. Apex rounded; antapex rounded to weakly bilobate. Epicyst and hypocyst appear to be more or less equal in size.
Wall relationships: Usually acavate with autophragm only; rarely circumcavate, with periphragm and endophragm narrowly separated.
Wall features: Periphragm or autophragm smooth to granulate. Processes are concentrated marginally and may show alignment; they are hollow, thin, tapering, distally expanded, sometimes with a subterminal constriction, and generally closed and furcate. Processes occasionally bifurcate. Process length about one sixth to one eighth of the length of the central body and with a length-to-breadth ratio of about 6:1. Processes may have annular thickenings (or septa).
Mode of excystment: Usually involves the loss of a large hexa isodeltaform 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 between paraplates adjacent to 2a appear to develop 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 presumed to be peridinialean; occasional alignment of processes suggests a paracingulum and possibly other parasutures. Parasulcus not identified.
Dimensions/Size:
Holotype: body length 88 µm, body width 57 µm, maximum length of processes 17 µm.
Range: body length 66(87)114 µm (26 specimens), body width 56(75)96 µm (26 specimens), minimum length of processes 6(10)14 µm (20 specimens), maximum length of processes 9(14)22 µm (26 specimens).
Affinities:
Barssidinium wrennii, Barssidinium evangelineae, and Barssidinium graminosum are differentiated on the basis of the processes. Both B. wrennii and B. graminosum differ from B. evangelineae in having distally closed, furcate processes, in contrast to the distally open, aculeate processes of B. evangelineae. The length of the processes in B. wrennii and B. graminosum is different: in B. wrennii the process length is about one sixth to one eighth of the length of the central body; in B. graminosum, the process length is about one third to one fifth of the length of the central body. Although the process length in B. evangelineae is typically shorter than that in B. wrennii, there is some overlap.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Barssidinium wrennii Lentin et al., 1994, has hollow, thin, tapering processes that are generally closed and furcate distally. Process length about 1/6 to 1/8th of length of central body. Barssidinium graminosum has processes that are 1/5th to 1/3rd the length of the central body.
Size: body length 68-114 µm, width 56-96 µm. Minimum length of processes 6-14 µm, maximum length of processes 9-22 µm.