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Cleistosphaeridium palmatum
From Fensome et al., 2019:
Fensome et al., 2016b, p.37, pl.4, figs.13–16. Holotype: Fensome et al., 2016b, pl.4, figs.13–14. Age:
last occurrence is Early Eocene.
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Original description Fensome et al., 2016b:
Holotype. Plate 4, figs 13, 14 from a cuttings sample at 2450–2460 m in Roberval K-92: GSC type collection no. 137897, sample P17706, slide 01, co-ordinates 6.9 × 100.6, England Finder G30/0‒2. Maximum overall diameter 87 μm, maximum diameter of central body 50 μm, maximum length of processes 25 μm. The age determined for the sample from which the holotype was recovered is early Ypresian.
Etymology. The epithet is from the Latin palmatus, meaning marked or shaped like the palm of the hand, in reference to the shape of the distal terminations of the processes.
Diagnosis. A species of Cleistosphaeridium in which the solid processes are of irregular width, varying from 1–7 μm and distally slender to splayed, with some adjacent processes interconnected distally, commonly so that they form arches.
Description. The processes are of irregular width, distally slender to splayed, with some adjacent processes interconnected distally. They are predominantly dolobrate, but some are bifid. The wall of the central body is generally less than 1 μm thick. Archaeopyle apical, with formula A(1–4´), operculum attached or free. Other aspects of the tabulation cannot be determined, as specimens possess more than one process per plate, sometimes in complexes. Where present, the complexes appear to occur on the precingular, postcingular and antapical plates.
Size. Maximum diameter of central body 48 μm, length of processes 10–25 μm, four specimens measured.
Age. LO: late Ypresian.
Remarks. The processes of specimens belonging to this species show similarities to those found in Adnatosphaeridium, Enneadocysta, Licracysta and other species of Cleistosphaeridium. Although the distal branches of processes can sometimes be interconnected, the general absence of trabecula uniting processes precludes assignment of the species to Adnatosphaeridium. Cleistosphaeridium palmatum differs from species of Enneadocysta because the number of processes per plate (where discernible as being related to tabulation) invariably exceeds one, and distally processes are dolobrate rather than licrate or clypeate. Moreover, the antapex of Cleistosphaeridium palmatum is not characterised by two processes (see Fensome et al. 2007, p. 394). Cleistosphaeridium diversispinosum differs in not having branched processes in which the branches often meet along their length or distally and in not having spatulate endings. Specimens of the species Cleistosphaeridium polypetellum are slender and are not spatulate or branched distally; species of Licracysta have proximal and ventral surfaces on which processes are absent or reduced.
Fensome et al., 2016b, p.37, pl.4, figs.13–16. Holotype: Fensome et al., 2016b, pl.4, figs.13–14. Age:
last occurrence is Early Eocene.
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Original description Fensome et al., 2016b:
Holotype. Plate 4, figs 13, 14 from a cuttings sample at 2450–2460 m in Roberval K-92: GSC type collection no. 137897, sample P17706, slide 01, co-ordinates 6.9 × 100.6, England Finder G30/0‒2. Maximum overall diameter 87 μm, maximum diameter of central body 50 μm, maximum length of processes 25 μm. The age determined for the sample from which the holotype was recovered is early Ypresian.
Etymology. The epithet is from the Latin palmatus, meaning marked or shaped like the palm of the hand, in reference to the shape of the distal terminations of the processes.
Diagnosis. A species of Cleistosphaeridium in which the solid processes are of irregular width, varying from 1–7 μm and distally slender to splayed, with some adjacent processes interconnected distally, commonly so that they form arches.
Description. The processes are of irregular width, distally slender to splayed, with some adjacent processes interconnected distally. They are predominantly dolobrate, but some are bifid. The wall of the central body is generally less than 1 μm thick. Archaeopyle apical, with formula A(1–4´), operculum attached or free. Other aspects of the tabulation cannot be determined, as specimens possess more than one process per plate, sometimes in complexes. Where present, the complexes appear to occur on the precingular, postcingular and antapical plates.
Size. Maximum diameter of central body 48 μm, length of processes 10–25 μm, four specimens measured.
Age. LO: late Ypresian.
Remarks. The processes of specimens belonging to this species show similarities to those found in Adnatosphaeridium, Enneadocysta, Licracysta and other species of Cleistosphaeridium. Although the distal branches of processes can sometimes be interconnected, the general absence of trabecula uniting processes precludes assignment of the species to Adnatosphaeridium. Cleistosphaeridium palmatum differs from species of Enneadocysta because the number of processes per plate (where discernible as being related to tabulation) invariably exceeds one, and distally processes are dolobrate rather than licrate or clypeate. Moreover, the antapex of Cleistosphaeridium palmatum is not characterised by two processes (see Fensome et al. 2007, p. 394). Cleistosphaeridium diversispinosum differs in not having branched processes in which the branches often meet along their length or distally and in not having spatulate endings. Specimens of the species Cleistosphaeridium polypetellum are slender and are not spatulate or branched distally; species of Licracysta have proximal and ventral surfaces on which processes are absent or reduced.