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Impagidinium witmeri
Plate 1, figs. A–L
Synonym. “Impagidinium speciosum” Witmer, unpublished, PhD thesis 1987, Plate 11, figs. 1–8, p. 535.
Derivation of name. Named for Dr. Roger J. Witmer, in recognition of his achievements in marine palynology and organic geochemistry.
Diagnosis. An intermediate- to large-sized species of Impagidinium that is characterized by robust, suturocavate, denticulate, parasutural septa, of intermediate height, with the occasional development of rudimentary gonal processes.
Holotype. Plate 1, figs. A–C, SDB 204.84m B19.4.
Paratypes. Paratype 1, Plate 1, figs. D–E, CL 98.62m
K48.1. Paratype 2, Plate 1, figs. F–I, MCBR1 15.40m
E42. Paratype 3, Plate 1, figs. G–H, MCBR1 15.40m N38.
Paratype 4, Plate 1, figs. J–L, SDB 204.84m P39.
Material. South Dover Bridge (SDB) core, Talbot County, Maryland, USA.
Type locality and horizon. South Dover Bridge (SDB) core, latest Paleocene, 204.84 m.
Age. Latest Paleocene.
Description.
Shape: Spherical to ellipsoidal.
Wall relationships: Endophragm smooth (up to 2 μm thick), overlain by a faintly granulate periphragm (up to 1 μm thick). Periphragm closely appressed except for below the denticulate (para)sutural septa.
Wall features: oval cysts characterized by rather robust (para)sutural septa. The apical septa typically merge into a small apical horn-like protrusion.
Processes: the (para)sutural septa give rise to rudimentary processes at gonal junctions.
Paratabulation: indicated by (para)sutural septa, also clearly indicating an S-type (para)cingulum. (Para)cingular and sulcal plate sutures typically only faintly indicated.
Archeopyle: indicated by the loss of 300, operculum free.
Paracingulum: S-type (para)cingulum. (Para)cingular and sulcal plate sutures typically only faintly indicated.
Parasulcus: (Para)cingular and sulcal plate sutures typically only faintly indicated.
Dimensions. Holotype: endocyst 58 μm; pericyst 68 μm parasutural fold bases up to 9 μm across; parasutural fold heights up to 4 μm. Other types: Endocyst size 55–62 μm, pericyst size 61–73 μm, fold bases 5–10 μm and fold heights 3–5 μm (n D 6).
Stratigraphic range/occurrence. Latest Paleocene–earliest Eocene.
Remarks. This species differs from other Impagidinium species by its robust parasutural septa, with the tendency to develop suturocavation, akin to non-cavate species of Pentadinium. Roger Witmer first identified this taxon during his PhD studies (unpublished) (Witmer, 1987).
Synonym. “Impagidinium speciosum” Witmer, unpublished, PhD thesis 1987, Plate 11, figs. 1–8, p. 535.
Derivation of name. Named for Dr. Roger J. Witmer, in recognition of his achievements in marine palynology and organic geochemistry.
Diagnosis. An intermediate- to large-sized species of Impagidinium that is characterized by robust, suturocavate, denticulate, parasutural septa, of intermediate height, with the occasional development of rudimentary gonal processes.
Holotype. Plate 1, figs. A–C, SDB 204.84m B19.4.
Paratypes. Paratype 1, Plate 1, figs. D–E, CL 98.62m
K48.1. Paratype 2, Plate 1, figs. F–I, MCBR1 15.40m
E42. Paratype 3, Plate 1, figs. G–H, MCBR1 15.40m N38.
Paratype 4, Plate 1, figs. J–L, SDB 204.84m P39.
Material. South Dover Bridge (SDB) core, Talbot County, Maryland, USA.
Type locality and horizon. South Dover Bridge (SDB) core, latest Paleocene, 204.84 m.
Age. Latest Paleocene.
Description.
Shape: Spherical to ellipsoidal.
Wall relationships: Endophragm smooth (up to 2 μm thick), overlain by a faintly granulate periphragm (up to 1 μm thick). Periphragm closely appressed except for below the denticulate (para)sutural septa.
Wall features: oval cysts characterized by rather robust (para)sutural septa. The apical septa typically merge into a small apical horn-like protrusion.
Processes: the (para)sutural septa give rise to rudimentary processes at gonal junctions.
Paratabulation: indicated by (para)sutural septa, also clearly indicating an S-type (para)cingulum. (Para)cingular and sulcal plate sutures typically only faintly indicated.
Archeopyle: indicated by the loss of 300, operculum free.
Paracingulum: S-type (para)cingulum. (Para)cingular and sulcal plate sutures typically only faintly indicated.
Parasulcus: (Para)cingular and sulcal plate sutures typically only faintly indicated.
Dimensions. Holotype: endocyst 58 μm; pericyst 68 μm parasutural fold bases up to 9 μm across; parasutural fold heights up to 4 μm. Other types: Endocyst size 55–62 μm, pericyst size 61–73 μm, fold bases 5–10 μm and fold heights 3–5 μm (n D 6).
Stratigraphic range/occurrence. Latest Paleocene–earliest Eocene.
Remarks. This species differs from other Impagidinium species by its robust parasutural septa, with the tendency to develop suturocavation, akin to non-cavate species of Pentadinium. Roger Witmer first identified this taxon during his PhD studies (unpublished) (Witmer, 1987).