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Pseudoceratium iehiense
From Fensome et al., 2019:
Pseudoceratium iehiense Helby and May in Helby, 1987, p.315–316, figs.16A–K,17.
Holotype: Helby, 1987, figs.16I–J; Fensome et al., 1996, figs.1–2 — p.2153; Fensome et al., 2019a, figs.19A–B. Fensome et al. (2019, p.520) unintentionally questioned the generic assignment in error.
Age: late Tithonian–early Berriasian.
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Original description: Helby and May in Helby, 1987, p. 315-316
Proximate cyst, compressed ceratioid with single apical, antapical and postcingular horns. Cyst wall 2-layered, comprised of autophragm and ectophragm with relatively closely spaced projections and short discontinuous ridges within the ectoceol. Autophragm smooth, less than µm thick. Ectophragm essentially continuous, surface expression variable including coarsely reticulate, granulate and smooth, 1-1.5µm thick. Ectophragm supported by irregularly disseminated projections and short ridges below most of the plate surface, but closely packed in parasutural regions, generally 0.5-1µm in length, but up to 5µm in length in parasutural regions. Paratabulation indicated mainly by principal accessory archeopyle sutures and faint parasutural ridging due to the greater height of the autophragm projections adjacent to the parasutures. Formula 4', 6'', Xc, 6''', 1p, 1'''' (Fig.17). Archeopyle apical, type [tA], principal archeopyle suture zigzag, parasulcal notch offset. Operculum normally free. Paracingulum indicated by low, transverse, linear markings across dorsal surface, by a slight equatorial bulge on the left side of the cyst and by a similar bulge at the anterior limit of the right lateral horn. Paracingulum not well defined on ventral surface but its ends are markedly offset against parasulcus (Fig.17). Parasulcus not well defined, but on occasional
specimens it is distinctly sinuous (Fig.l 6G) twisting from left ventral on the epicyst to midventral on the hypocyst. Measurements. Twenty-eight specimens from Zeewulf-l at 3085 m, in the P. iehiense Zone were measured as:--A, 83(96)114 µm; B, 71(78)94 µm; C, 128-161 µm (6 specimens).
Affinities:
Helby and May in Helby 1987, p. 316: Pseudoceratium iehiense resembles P. pelliferum but that species differs in not having a continuous ectophragm (Gocht, 1957, pl.18, figs 1,2; Wall & Evitt, 1975, pl.1, figs 12-17). There are however, some limited distal connections between the projections on the autophragm of P. pelliferum (Wall & Evitt, pl.1, fig. 17). Duxbury (in Thusu, 1978, pl.1, fig.4) assigned to P. pelliferum a specimen which appears to have a distinct ectophragm. This form differs from P. iehiense in possessing narrow, attenuated horns rather than the robust horns of the latter. Pseudoceratium weymouthense is larger and has substantially longer horns.
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Comments Fensome et al., 2019a:
Helby (1987, p. 315) noted that this distinctive species has a wall with closely spaced projections and short, discontinuous ridges between the endophragm and periphragm. The ectophragm is essentially continuous, with a coarsely reticulate, granulate or smooth surface. The ornament within the ectocoel is more closely packed and commonly higher in pandasutural regions. Helby (1987) stated that Pseudoceratium weymouthensis is larger and has “substantially longer horns”.
Stratigraphical occurrence. Helby (1987) described Pseudoceratium iehiense from the upper Tithonian to lower Berriasian of subsurface Papua New Guinea.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Pseudoceratium iehiense Helby and May in Helby, 1987. This species has projections supporting the essentially continuous ectophragm which is coarsely reticulate, granulate and smooth and single apical, cingular and antapical horns. It differs from P. pelliferum in having a continuous ectophragm. Size: loisthocyst length 83-14 µm, width 71-94 µm, overall length with horns 128-161 µm.
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Pseudoceratium iehiense Helby and May in Helby, 1987, p.315–316, figs.16A–K,17.
Holotype: Helby, 1987, figs.16I–J; Fensome et al., 1996, figs.1–2 — p.2153; Fensome et al., 2019a, figs.19A–B. Fensome et al. (2019, p.520) unintentionally questioned the generic assignment in error.
Age: late Tithonian–early Berriasian.
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Original description: Helby and May in Helby, 1987, p. 315-316
Proximate cyst, compressed ceratioid with single apical, antapical and postcingular horns. Cyst wall 2-layered, comprised of autophragm and ectophragm with relatively closely spaced projections and short discontinuous ridges within the ectoceol. Autophragm smooth, less than µm thick. Ectophragm essentially continuous, surface expression variable including coarsely reticulate, granulate and smooth, 1-1.5µm thick. Ectophragm supported by irregularly disseminated projections and short ridges below most of the plate surface, but closely packed in parasutural regions, generally 0.5-1µm in length, but up to 5µm in length in parasutural regions. Paratabulation indicated mainly by principal accessory archeopyle sutures and faint parasutural ridging due to the greater height of the autophragm projections adjacent to the parasutures. Formula 4', 6'', Xc, 6''', 1p, 1'''' (Fig.17). Archeopyle apical, type [tA], principal archeopyle suture zigzag, parasulcal notch offset. Operculum normally free. Paracingulum indicated by low, transverse, linear markings across dorsal surface, by a slight equatorial bulge on the left side of the cyst and by a similar bulge at the anterior limit of the right lateral horn. Paracingulum not well defined on ventral surface but its ends are markedly offset against parasulcus (Fig.17). Parasulcus not well defined, but on occasional
specimens it is distinctly sinuous (Fig.l 6G) twisting from left ventral on the epicyst to midventral on the hypocyst. Measurements. Twenty-eight specimens from Zeewulf-l at 3085 m, in the P. iehiense Zone were measured as:--A, 83(96)114 µm; B, 71(78)94 µm; C, 128-161 µm (6 specimens).
Affinities:
Helby and May in Helby 1987, p. 316: Pseudoceratium iehiense resembles P. pelliferum but that species differs in not having a continuous ectophragm (Gocht, 1957, pl.18, figs 1,2; Wall & Evitt, 1975, pl.1, figs 12-17). There are however, some limited distal connections between the projections on the autophragm of P. pelliferum (Wall & Evitt, pl.1, fig. 17). Duxbury (in Thusu, 1978, pl.1, fig.4) assigned to P. pelliferum a specimen which appears to have a distinct ectophragm. This form differs from P. iehiense in possessing narrow, attenuated horns rather than the robust horns of the latter. Pseudoceratium weymouthense is larger and has substantially longer horns.
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Comments Fensome et al., 2019a:
Helby (1987, p. 315) noted that this distinctive species has a wall with closely spaced projections and short, discontinuous ridges between the endophragm and periphragm. The ectophragm is essentially continuous, with a coarsely reticulate, granulate or smooth surface. The ornament within the ectocoel is more closely packed and commonly higher in pandasutural regions. Helby (1987) stated that Pseudoceratium weymouthensis is larger and has “substantially longer horns”.
Stratigraphical occurrence. Helby (1987) described Pseudoceratium iehiense from the upper Tithonian to lower Berriasian of subsurface Papua New Guinea.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Pseudoceratium iehiense Helby and May in Helby, 1987. This species has projections supporting the essentially continuous ectophragm which is coarsely reticulate, granulate and smooth and single apical, cingular and antapical horns. It differs from P. pelliferum in having a continuous ectophragm. Size: loisthocyst length 83-14 µm, width 71-94 µm, overall length with horns 128-161 µm.
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