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Barssidinium
From Williams et al., 2017:
[Barssidinium, Lentin et al., 1994, p. 575, 577; Emendation: De Schepper et al., 2004, p. 634
Type species: Barssidinium wrennii, Lentin et al., 1994 (pl.2, figs.2,5)]
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Original description: [Lentin et al., 1994]:
Diagnosis:
Acavate to narrowly circumcavate, dorsoventrally compressed peridinialean cysts with the single or outer wall layer being laevigate to granulate. Processes typically tend to show a strong marginate concentration, but occasionally have a more uniform distribution.
Processes generally hollow, tubiform to tapering, sometimes with striae and annular thickenings (or septa) along their length; they are distally open or closed and furcate.
The archeopyle usually involves the middorsal intercalary alone, which is large hexa isodeltaform, posteriorly extending almost to the equator of the cyst.
Description:
Shape: 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 laevigate to scabrate to granulate. Processes generally hollow, tubiform or tapering, commonly expanded distally, with or without a subterminal constriction; they may be open with an aculeate rim (Fig. 3H) or closed with several small offshoots (Fig. 3G). Annular thickenings (or septa) may occur on or within processes, especially the closed furcate type. Longitudinal striations may occur on the surface of open aculeate processes. Processes are concentrated marginally but may also occur in dorsal or ventral regions in some specimens. Endophragm, where observed, thin and laevigate.
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.
Affinities:
Barssidinium differs from Sumatradinium in having a laevigate to granulate, rather than a reticulate to semireticulate, ornamentation on the central body. Multispinula Bradford, 1975, Selenopemphix Benedek, 1972, and Trinovantedinium Reid, 1977 superficially resemble Barssidinium in shape, in the presence of processes and in the development of an intercalary archeopyle. However, Multispinula and Selenopemphix are typically compressed apically-antapically and have processes that tend to be concentrated around the cingulum. Additionally, Selenopemphix has an offset intercalary archeopyle in contrast to the middorsal archeopyle usual for Sumatradinium. In Trinovantedinium Reid, 1977, the processes tend to be short and solid. They show a distinctly penitabulate arrangement and occur middorsally and midventrally. In contrast, the processes in Barssidinium are hollow, possess annulate thickenings or possibly septa, do not show a distinct penitabulate arrangement, and tend to have a strong, marginate concentration. Trinovantedinium usually has an apical horn, boss, or process complex (L. de Verteuil, pers. comm., 1993), none of which has been observed in Barssidinium. In addition, the operculum in Trinovantedinium is consistently detached, whereas the operculum in Barssidinium almost always remains attached, with the anterior suture being the last to separate. Xandarodinium Reid, 1977 also represents peridinialean cysts with processes. However, these are uniformly distributed and the archeopyle in that genus is problematic. Apectodinium (Costa and Downie, 1976) Lentin and Williams, 1977 has a similar shape but a uniform distribution of processes. Moreover, the archeopyle is much smaller than that of Barssidinium relative to overall cyst size; it is anteriorly located and apparently quadra rather than hexa isodeltaform as in Barssidinium. Trivalvadinium Islam, 1983 is similar to Barssidinium in overall shape and in its wall relationships; however, it differs in having an archeopyle involving the loss of three intercalary plates and processes that are more or less uniformly distributed. Although some specimens of Barssidinium appear to have accessory archeopyle sutures, a distinctive 3I archeopyle has not been observed. As in Sumatradinium, eastern Canadian specimens of Barssidinium rarely show distinctive primary pigmentation, although this may be a feature of specimens from some areas (M.J. Head, pers. comm., 1992).
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Emended descriptions:
De Schepper et al., 2004:
Diagnosis:
Dorsoventrally compressed protoperidinialean cysts with subcircular to rounded pentagonal ambitus. Central body brown in color; wall has two closely appressed layers. Wall surface smooth to granulate. Process distribution usually concentrated around ambitus; may reflect tabulation. Processes hollow, tubiform to tapering, usually with annular thickenings along length; distally open or closed. Faint and fine sutural lineations, incompletely reflecting tabulation, variably developed over surface.
Archeopyle 2a hexa or penta intercalary, rounded angles, occasional accessory sutures.
Operculum free or adherent.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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 Lentin et al., 1994, differs from Sumatradinium in having a laevigate to granulate, rather than a reticulate to semireticulate ornamentation on the body. Multispinula, Selenopemphix and Trinovantedinium superficially resemble Barssidinium in shape, presence of processes and intercalary archeopyle. However, Multispinula and Selenopemphix are typically compressed apically-antapically and their processes tend to be concentrated around the cingulum. Also the archeopyle is offset in Selenopemphix. In Trinovantedinium the processes tend to be short and solid. They show a distinctly penitabulate arrangement and occur middorsally and midventrally. Also, Trinovantedinium usually has an apical horn, boss or process complex. And the operculum is always detached. In Barssidinium the operculum remains attached with the anterior suture being the last to separate. Xandarodinium has processes uniformly distributed on the body and the archeopyle is problematic.
[Barssidinium, Lentin et al., 1994, p. 575, 577; Emendation: De Schepper et al., 2004, p. 634
Type species: Barssidinium wrennii, Lentin et al., 1994 (pl.2, figs.2,5)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Lentin et al., 1994]:
Diagnosis:
Acavate to narrowly circumcavate, dorsoventrally compressed peridinialean cysts with the single or outer wall layer being laevigate to granulate. Processes typically tend to show a strong marginate concentration, but occasionally have a more uniform distribution.
Processes generally hollow, tubiform to tapering, sometimes with striae and annular thickenings (or septa) along their length; they are distally open or closed and furcate.
The archeopyle usually involves the middorsal intercalary alone, which is large hexa isodeltaform, posteriorly extending almost to the equator of the cyst.
Description:
Shape: 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 laevigate to scabrate to granulate. Processes generally hollow, tubiform or tapering, commonly expanded distally, with or without a subterminal constriction; they may be open with an aculeate rim (Fig. 3H) or closed with several small offshoots (Fig. 3G). Annular thickenings (or septa) may occur on or within processes, especially the closed furcate type. Longitudinal striations may occur on the surface of open aculeate processes. Processes are concentrated marginally but may also occur in dorsal or ventral regions in some specimens. Endophragm, where observed, thin and laevigate.
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.
Affinities:
Barssidinium differs from Sumatradinium in having a laevigate to granulate, rather than a reticulate to semireticulate, ornamentation on the central body. Multispinula Bradford, 1975, Selenopemphix Benedek, 1972, and Trinovantedinium Reid, 1977 superficially resemble Barssidinium in shape, in the presence of processes and in the development of an intercalary archeopyle. However, Multispinula and Selenopemphix are typically compressed apically-antapically and have processes that tend to be concentrated around the cingulum. Additionally, Selenopemphix has an offset intercalary archeopyle in contrast to the middorsal archeopyle usual for Sumatradinium. In Trinovantedinium Reid, 1977, the processes tend to be short and solid. They show a distinctly penitabulate arrangement and occur middorsally and midventrally. In contrast, the processes in Barssidinium are hollow, possess annulate thickenings or possibly septa, do not show a distinct penitabulate arrangement, and tend to have a strong, marginate concentration. Trinovantedinium usually has an apical horn, boss, or process complex (L. de Verteuil, pers. comm., 1993), none of which has been observed in Barssidinium. In addition, the operculum in Trinovantedinium is consistently detached, whereas the operculum in Barssidinium almost always remains attached, with the anterior suture being the last to separate. Xandarodinium Reid, 1977 also represents peridinialean cysts with processes. However, these are uniformly distributed and the archeopyle in that genus is problematic. Apectodinium (Costa and Downie, 1976) Lentin and Williams, 1977 has a similar shape but a uniform distribution of processes. Moreover, the archeopyle is much smaller than that of Barssidinium relative to overall cyst size; it is anteriorly located and apparently quadra rather than hexa isodeltaform as in Barssidinium. Trivalvadinium Islam, 1983 is similar to Barssidinium in overall shape and in its wall relationships; however, it differs in having an archeopyle involving the loss of three intercalary plates and processes that are more or less uniformly distributed. Although some specimens of Barssidinium appear to have accessory archeopyle sutures, a distinctive 3I archeopyle has not been observed. As in Sumatradinium, eastern Canadian specimens of Barssidinium rarely show distinctive primary pigmentation, although this may be a feature of specimens from some areas (M.J. Head, pers. comm., 1992).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
De Schepper et al., 2004:
Diagnosis:
Dorsoventrally compressed protoperidinialean cysts with subcircular to rounded pentagonal ambitus. Central body brown in color; wall has two closely appressed layers. Wall surface smooth to granulate. Process distribution usually concentrated around ambitus; may reflect tabulation. Processes hollow, tubiform to tapering, usually with annular thickenings along length; distally open or closed. Faint and fine sutural lineations, incompletely reflecting tabulation, variably developed over surface.
Archeopyle 2a hexa or penta intercalary, rounded angles, occasional accessory sutures.
Operculum free or adherent.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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 Lentin et al., 1994, differs from Sumatradinium in having a laevigate to granulate, rather than a reticulate to semireticulate ornamentation on the body. Multispinula, Selenopemphix and Trinovantedinium superficially resemble Barssidinium in shape, presence of processes and intercalary archeopyle. However, Multispinula and Selenopemphix are typically compressed apically-antapically and their processes tend to be concentrated around the cingulum. Also the archeopyle is offset in Selenopemphix. In Trinovantedinium the processes tend to be short and solid. They show a distinctly penitabulate arrangement and occur middorsally and midventrally. Also, Trinovantedinium usually has an apical horn, boss or process complex. And the operculum is always detached. In Barssidinium the operculum remains attached with the anterior suture being the last to separate. Xandarodinium has processes uniformly distributed on the body and the archeopyle is problematic.