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Impagidinium strialatum
Impagidinium strialatum (Wall, 1967) Stover and Evitt, 1978
Originally Leptodinium, subsequently (and now) Impagidinium.
Holotype: Wall, 1967, pl.15, fig.9
Locus typicus: Core A254/330, depth 355, Yucatan Basin (19¦ 35" N, 84¦ 51" W)
Stratum typicum: Middle Miocene-Holocene
Original diagnosis: Wall, 1967, p. 107: Leptodinium strialatum
A small species of Leptodinium with relatively broad, weakly radially striate sutural septa reduced in the ventral area.
Original description: Wall, 1967, p. 107: Leptodinium strialatum
The test is ovoid with broadly rounded apices and smooth to weakly microgranular. It is ornamented by relatively broad sutural septa (equivalent to between one-fifth and a quarter of the equatorial diameter) with weak radial striations. These indicate a tabulation of 3-4", 0a, 6"", 6g, 5""", 1p, 1"""", whose basic pattern follows that of Leptodinium aculeatum and L. paradoxum, but in L. strialatum the septa are so reduced in several places that there are large, open compound areas on the test. These include two conspicuous longitudinal ventral areas where the cingular plates 6g and 1g are so reduced that the girdle is scarcely recognizable between the pre- and post-cingular series. The cingular areas on the dorsal surface also are reduced, only area 4g being complete and visible below the precingular archeopyle (3""). There is no longitudinal septum between the archeopyle and the fourth precingular area. The structure of the ventral region is not easily discernible but there appear to be one or two minute ventral apical plates (1" and 4"), a small anterior sulcal platelet, and a reduced sixth precingular plate-area. In this region the girdle appears to be displaced by its own width. The longitudinal furrow, too, is poorly defined; its left marginis very weakly developed in particular, but posteriorly there is a conspicuous posterior sulcal plate-area and a posterior intercalary area. Below these there is a square antapical area.
Affinities:
Wall, 1967, p. 108: Leptodinium strialatum
Pentadinium laticinctum Gerlach 1961 is similar in overall appearance but is considerably larger and different in details of tabulation.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 468, pl.21, fig.8,10: Impagidinium cf. strialatum
These forms resemble I. strialatum in the weak radial striation of the septa. The septa in the present forms are narrower and less distinct, however.
Originally Leptodinium, subsequently (and now) Impagidinium.
Holotype: Wall, 1967, pl.15, fig.9
Locus typicus: Core A254/330, depth 355, Yucatan Basin (19¦ 35" N, 84¦ 51" W)
Stratum typicum: Middle Miocene-Holocene
Original diagnosis: Wall, 1967, p. 107: Leptodinium strialatum
A small species of Leptodinium with relatively broad, weakly radially striate sutural septa reduced in the ventral area.
Original description: Wall, 1967, p. 107: Leptodinium strialatum
The test is ovoid with broadly rounded apices and smooth to weakly microgranular. It is ornamented by relatively broad sutural septa (equivalent to between one-fifth and a quarter of the equatorial diameter) with weak radial striations. These indicate a tabulation of 3-4", 0a, 6"", 6g, 5""", 1p, 1"""", whose basic pattern follows that of Leptodinium aculeatum and L. paradoxum, but in L. strialatum the septa are so reduced in several places that there are large, open compound areas on the test. These include two conspicuous longitudinal ventral areas where the cingular plates 6g and 1g are so reduced that the girdle is scarcely recognizable between the pre- and post-cingular series. The cingular areas on the dorsal surface also are reduced, only area 4g being complete and visible below the precingular archeopyle (3""). There is no longitudinal septum between the archeopyle and the fourth precingular area. The structure of the ventral region is not easily discernible but there appear to be one or two minute ventral apical plates (1" and 4"), a small anterior sulcal platelet, and a reduced sixth precingular plate-area. In this region the girdle appears to be displaced by its own width. The longitudinal furrow, too, is poorly defined; its left marginis very weakly developed in particular, but posteriorly there is a conspicuous posterior sulcal plate-area and a posterior intercalary area. Below these there is a square antapical area.
Affinities:
Wall, 1967, p. 108: Leptodinium strialatum
Pentadinium laticinctum Gerlach 1961 is similar in overall appearance but is considerably larger and different in details of tabulation.
Heilmann-Clausen in Heilmann-Clausen and Costa, 1989, p. 468, pl.21, fig.8,10: Impagidinium cf. strialatum
These forms resemble I. strialatum in the weak radial striation of the septa. The septa in the present forms are narrower and less distinct, however.