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Impagidinium aculeatum
Impagidinium aculeatum (Wall, 1967) Lentin and Williams, 1981
Originally Leptodinium, subsequently (and now) Impagidinium.
Holotype: Wall, 1967, pl.14, fig.18; Jan du Chêne et al., 1986, pl.53, figs.1-3
Locus typicus: Core 254/327, Yucatan Basin (20¦ 45" N, 83¦ 00" W)
Stratum typicum: Pleistocene-Holocene
Original diagnosis: Wall, 1967, p. 104: Leptodinium aculeatum
A relatively small, ovoid species with a relatively wide girdle zone and extensive ventral area; test hyaline with sutural septa most strongly developed in the posterior intercalary area; precingular plate-area 6"" very narrow.
Dimensions. Test only 28-38 µm long; septa up to 95 µm high. Over 100 specimens.
Original description: Wall, 1967, p. 104-105: Leptodinium aculeatum
The test is ovoid and divided into more or less equal epithecal and hypothecal regions by a relatively wide, weakly descending girdle, displaced by its own width ventrallv. It is ornamented by hyaline, sutural septa whose maximum elevation (equivalent to one-quarter of the diameter) is found at the corners of plate-areas and along the left margin of the ventral area, especially near the posterior intercalary area; in between the septa are lower. At the equator the septa are inclined so that the girdle plate-areas widen distally. The tabulation is 3-4", 0a, 6"", 6g, 5""", 1p, 1"""". There are two pentagonal dorsal apical plate-areas (2", 3") and two minute median ventral areas (1",4"). Precingular areas 1"" to 5"" are subrectangular, the sixth is linear and narrow; plate-area 3"" forms a trapezoidal archeopyle. There are five subrectangular postcingular areas, 1""" and 5""" being smaller than the others; the adjacent posterior intercalary plate-area is small and the outer test wall may be completely separated from the inner at this point. There is a single small, subquadrangular antapical area. The longitudinal furrow occupies almost the entire length of the ventral area, extending well into the epitheca. It occupies approximately one-third of the equatorial diameter and widens slightly posteriorly.
Originally Leptodinium, subsequently (and now) Impagidinium.
Holotype: Wall, 1967, pl.14, fig.18; Jan du Chêne et al., 1986, pl.53, figs.1-3
Locus typicus: Core 254/327, Yucatan Basin (20¦ 45" N, 83¦ 00" W)
Stratum typicum: Pleistocene-Holocene
Original diagnosis: Wall, 1967, p. 104: Leptodinium aculeatum
A relatively small, ovoid species with a relatively wide girdle zone and extensive ventral area; test hyaline with sutural septa most strongly developed in the posterior intercalary area; precingular plate-area 6"" very narrow.
Dimensions. Test only 28-38 µm long; septa up to 95 µm high. Over 100 specimens.
Original description: Wall, 1967, p. 104-105: Leptodinium aculeatum
The test is ovoid and divided into more or less equal epithecal and hypothecal regions by a relatively wide, weakly descending girdle, displaced by its own width ventrallv. It is ornamented by hyaline, sutural septa whose maximum elevation (equivalent to one-quarter of the diameter) is found at the corners of plate-areas and along the left margin of the ventral area, especially near the posterior intercalary area; in between the septa are lower. At the equator the septa are inclined so that the girdle plate-areas widen distally. The tabulation is 3-4", 0a, 6"", 6g, 5""", 1p, 1"""". There are two pentagonal dorsal apical plate-areas (2", 3") and two minute median ventral areas (1",4"). Precingular areas 1"" to 5"" are subrectangular, the sixth is linear and narrow; plate-area 3"" forms a trapezoidal archeopyle. There are five subrectangular postcingular areas, 1""" and 5""" being smaller than the others; the adjacent posterior intercalary plate-area is small and the outer test wall may be completely separated from the inner at this point. There is a single small, subquadrangular antapical area. The longitudinal furrow occupies almost the entire length of the ventral area, extending well into the epitheca. It occupies approximately one-third of the equatorial diameter and widens slightly posteriorly.