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Impletosphaeridium prolatum
Impletosphaeridium prolatum Head et al., 1989
Holotype: Head et al., 1989, pl.6, fig.1
Holotype: Head et al., pl.6, fig.1
Locus typicus: Baffin Bay, North Atlantic
Stratum typicum: Middle? Miocene
Original diagnosis Head et al., 1989, p.491:
Central body is ovoidal, composed of two thin, closely appressed wall layers and possessing a smooth surface. Processes are narrow, nontapering, solid, unbranched, of equal length, and have expanded distal tips. Process distribution fairly regular and apparentlv nontabular.
Original description Head et al., 1989, p.491:
Periphragm usually appressed to endophragm but may be slightly wrinkled between process bases. Expanded process tips are about 1 Ám wide and form irregular, flattened platforms. An excystment aperture was not identified with certainty, but rupturing of the cyst body in the apical/subapical region was noted in a few specimen. A low rounded, thickened body, yellow in color and with a maximum length of 4 to 5 Ám, was seen in several specimens, including the holotype. It is unclear whether this feature is primary (as an omphalus) or preservational.
Dimensions: Holotype: central body length, 31 Ám; process leng 10 Ám. Range in central body length, 28 (33.4) 38 Ám. Range in process length, 5 (8.1) 12 Ám. Fourteen specimens were measured.
Remarks. This species appears somewhat similar to Impletosphaeridium ligospinosum (De Coninck) Islam, 1983 from the early Eocene ol Belgium. However, the latter has a somewhat smaller central body (20-25 Ám) and the precise nature of its processes cannot be determined from De Coninck"s illustrations. Impletosphaeridium insolitum Eaton, 1976 from the middle Eocene has a spherical to subspherical central body (15-24 Ám in diameter) and specimens typically possess both simple and bifurcate processes. Dioxya(?) pignerata Norris, 1986, recorded from the Paleogene of the Mackenzie Delta region of Canada (Norris, 1986; and as "Dinoflagellate sp. J-7" in Staplin, 1976) differs from I. prolatum in its larger size (body length = 45 to 83 Ám) and apparent presence of a combination AI archeopyle (Norris, 1986). A specimen figured by Dietrich et al., 1989 as Dioxya(?) pignerata, from the lower to middle Eocene of the western Beaufort Sea, is smaller (body length = 38 Ám, measured from the illustration) than the range recorded for D.(?) pignerata by Norris, 1986. This specimen, as far as can be judged from the illustration, might be conspecific with I. prolatum.
Holotype: Head et al., 1989, pl.6, fig.1
Holotype: Head et al., pl.6, fig.1
Locus typicus: Baffin Bay, North Atlantic
Stratum typicum: Middle? Miocene
Original diagnosis Head et al., 1989, p.491:
Central body is ovoidal, composed of two thin, closely appressed wall layers and possessing a smooth surface. Processes are narrow, nontapering, solid, unbranched, of equal length, and have expanded distal tips. Process distribution fairly regular and apparentlv nontabular.
Original description Head et al., 1989, p.491:
Periphragm usually appressed to endophragm but may be slightly wrinkled between process bases. Expanded process tips are about 1 Ám wide and form irregular, flattened platforms. An excystment aperture was not identified with certainty, but rupturing of the cyst body in the apical/subapical region was noted in a few specimen. A low rounded, thickened body, yellow in color and with a maximum length of 4 to 5 Ám, was seen in several specimens, including the holotype. It is unclear whether this feature is primary (as an omphalus) or preservational.
Dimensions: Holotype: central body length, 31 Ám; process leng 10 Ám. Range in central body length, 28 (33.4) 38 Ám. Range in process length, 5 (8.1) 12 Ám. Fourteen specimens were measured.
Remarks. This species appears somewhat similar to Impletosphaeridium ligospinosum (De Coninck) Islam, 1983 from the early Eocene ol Belgium. However, the latter has a somewhat smaller central body (20-25 Ám) and the precise nature of its processes cannot be determined from De Coninck"s illustrations. Impletosphaeridium insolitum Eaton, 1976 from the middle Eocene has a spherical to subspherical central body (15-24 Ám in diameter) and specimens typically possess both simple and bifurcate processes. Dioxya(?) pignerata Norris, 1986, recorded from the Paleogene of the Mackenzie Delta region of Canada (Norris, 1986; and as "Dinoflagellate sp. J-7" in Staplin, 1976) differs from I. prolatum in its larger size (body length = 45 to 83 Ám) and apparent presence of a combination AI archeopyle (Norris, 1986). A specimen figured by Dietrich et al., 1989 as Dioxya(?) pignerata, from the lower to middle Eocene of the western Beaufort Sea, is smaller (body length = 38 Ám, measured from the illustration) than the range recorded for D.(?) pignerata by Norris, 1986. This specimen, as far as can be judged from the illustration, might be conspecific with I. prolatum.