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Cristadinium headii
Cristadinium headii Willumsen et al., 2014, p.276–277, pl.1, figs.1–10.
Holotype: Willumsen et al., pl.1, figs.1–4.
Age: Aquitanian.
Original description (Willumsen et al., 2014)
Diagnosis. Large, dorso-ventrally compressed brown cyst with a pentagonal to subcircular peridinioid outline having one reduced apical and two antapical horns. The cingulum is planar to weakly helicoidal. Discontinuous unevenly serrated crests surmounted with elongated processes with acicular and bifid tips are present in the cingular and antapical areas. The apical and antapical tips have low (0.5–1 μm) crests or thickenings of the cyst walls. In dorsal-ventral view the apical horn is thickened and has a saw-tooth shape. The archaeopyle is isodeltaform hexa-intercalary in shape and involves paraplate 2a only. The operculum is most often in place and an archaeopyle outline is only recorded in one specimen.
Description. Large to small sparsely scattered solid processes with acicular to bifid tips, which occur on the cingulum and antapical part of the hypocyst. The thickening of the two antapical horns and the saw-tooth-shaped thickening of the apical horn in dorsal-ventral view is a diagnostic feature of this large protoperidinioid cyst. Lengths of the epicyst and hypocyst are approximately equal and the epicyst is conical with straight sides. Paratabulation indicated by discontinuous unevenly serrated crests which are surmounted with complex 3–14-μm-high processes with acicular or bifid tips. Crests are very unevenly serrated or surmounted by processes with acicular to bifid tips on the hypocyst, and low crests with a few solid spines are present on the apex. Processes are most prominent in the paracingular area close to the parasulcus and on the distal part of the antapical horns. The parasulcus is marked by continuous folds with low crests with ornament with a variation of acicular to bifid processes. The paracingular area is slightly inflated. Processes also occur in the precingular area and around the parasulcus, without any prominent developments of crests. Wall surface is smooth to finely granulate. The archaeopyle is isodeltaform hexa-intercalary, involving paraplate 2a only. (Plate 1 Figure 2).
Etymology. Named after palynologist Martin J. Head.
Types. Holotype. Plate 1, figures 1–4. sample 8, slide 8, EF U37/3. Paratype 1. Plate 1, figures 5–6 Borehole 8, sample 7, slide 08, EF N22. Paratype 2. Plate 1, figures 7–9, Borehole 8, sample 8, slide 07, EF H53/3, Borehole 1, at 1142 m depth, slide 07, 20um, EF R57/3.
Stratigraphical range. Reported from two Early Miocene (Aquitanian) samples, 7 and 8, in Borehole 8, offshore Angola. This new species has also been recorded in another Angolan borehole, no. 1, in a sample at 1142 m depth, where it co-occurs with Sumatradinium hamulatum (see Figure 2).
Dimensions. Holotype: width × length: 92 × 88 μm; four specimens measured; length 88 (82) 73 μm; width 92 (87) 73 μm; 10 processes measured: length of processes 3 (7) 14 μm.
Discussion. Cristadinium headii differs from the type species C. cristatoserratum (Head et al., 1989a) by having both ornaments developed as crests and individual elongated processes with acicular and bifid tips in the cingular and antapical areas. The distinct processes on C. headii sp. nov. differentiate it from the two other species in the genus Cristadinium, C. diminutivum and C. cristatoserratum (Head et al. 1989a, 1989b).
Holotype: Willumsen et al., pl.1, figs.1–4.
Age: Aquitanian.
Original description (Willumsen et al., 2014)
Diagnosis. Large, dorso-ventrally compressed brown cyst with a pentagonal to subcircular peridinioid outline having one reduced apical and two antapical horns. The cingulum is planar to weakly helicoidal. Discontinuous unevenly serrated crests surmounted with elongated processes with acicular and bifid tips are present in the cingular and antapical areas. The apical and antapical tips have low (0.5–1 μm) crests or thickenings of the cyst walls. In dorsal-ventral view the apical horn is thickened and has a saw-tooth shape. The archaeopyle is isodeltaform hexa-intercalary in shape and involves paraplate 2a only. The operculum is most often in place and an archaeopyle outline is only recorded in one specimen.
Description. Large to small sparsely scattered solid processes with acicular to bifid tips, which occur on the cingulum and antapical part of the hypocyst. The thickening of the two antapical horns and the saw-tooth-shaped thickening of the apical horn in dorsal-ventral view is a diagnostic feature of this large protoperidinioid cyst. Lengths of the epicyst and hypocyst are approximately equal and the epicyst is conical with straight sides. Paratabulation indicated by discontinuous unevenly serrated crests which are surmounted with complex 3–14-μm-high processes with acicular or bifid tips. Crests are very unevenly serrated or surmounted by processes with acicular to bifid tips on the hypocyst, and low crests with a few solid spines are present on the apex. Processes are most prominent in the paracingular area close to the parasulcus and on the distal part of the antapical horns. The parasulcus is marked by continuous folds with low crests with ornament with a variation of acicular to bifid processes. The paracingular area is slightly inflated. Processes also occur in the precingular area and around the parasulcus, without any prominent developments of crests. Wall surface is smooth to finely granulate. The archaeopyle is isodeltaform hexa-intercalary, involving paraplate 2a only. (Plate 1 Figure 2).
Etymology. Named after palynologist Martin J. Head.
Types. Holotype. Plate 1, figures 1–4. sample 8, slide 8, EF U37/3. Paratype 1. Plate 1, figures 5–6 Borehole 8, sample 7, slide 08, EF N22. Paratype 2. Plate 1, figures 7–9, Borehole 8, sample 8, slide 07, EF H53/3, Borehole 1, at 1142 m depth, slide 07, 20um, EF R57/3.
Stratigraphical range. Reported from two Early Miocene (Aquitanian) samples, 7 and 8, in Borehole 8, offshore Angola. This new species has also been recorded in another Angolan borehole, no. 1, in a sample at 1142 m depth, where it co-occurs with Sumatradinium hamulatum (see Figure 2).
Dimensions. Holotype: width × length: 92 × 88 μm; four specimens measured; length 88 (82) 73 μm; width 92 (87) 73 μm; 10 processes measured: length of processes 3 (7) 14 μm.
Discussion. Cristadinium headii differs from the type species C. cristatoserratum (Head et al., 1989a) by having both ornaments developed as crests and individual elongated processes with acicular and bifid tips in the cingular and antapical areas. The distinct processes on C. headii sp. nov. differentiate it from the two other species in the genus Cristadinium, C. diminutivum and C. cristatoserratum (Head et al. 1989a, 1989b).