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Ellipsodinium membraniferum
Ellipsodinium membraniferum Prince et al., 2008, p.92, pl.1, figs.4–6.
Holotype: Prince et al., 2008, pl.1, figs.4–6.
Age: late Santonian.
Original description (Prince et al., 2008):
Ellipsodinium membraniferum Prince, Jarvis, Pearce et Tocher, sp. nov. (Plate I, 4–6)
Holotype: Slide PRC 3964, WCI 117, E/F ref. W38/1, Whitecliff, Isle of Wight, England.
Paratype: Slide PRC 2761, FNP 6(2), E/F ref. P21/4, Foreness Point, east Kent, England.
Repository: Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Wales, UK.
Type locality: Whitecliff, Isle of Wight, England.
Stratigraphic horizon: Lower upper Santonian, upper U. socialis Zone.
Etymology: Membraniferum, with reference to the membranes that form the distinctive ridges.
Diagnosis: A round to slightly oval cyst which has longitudinal anastomosing ridges which are topped by membranes that have an irregular edge.
Description: Cyst round to slightly oval in shape, bearing longitudinal anastomosing ridges. The paracingulum is sometimes indicated by a single transverse ridge. All the ridges are topped by a membrane which forms a crest up to 6 µm high. This crest has a highly irregular edge and when viewed normal to the cyst surface gives the ridges a wavy appearance. The crests appear to be formed by the fusing of acicular spines which gives the crest a very irregular edge. The archaeopyle is precingular, type P. With the exception of the archaeopyle and the paracingulum (where present), no paratabulation is indicated.
Dimensions: Holotype: overall 24 µm wide × 36 µm long; crest height 4 µm. Range of 11 measured specimens: overall 24– 36 µm (average 29 µm) wide × 26–37 µm (average 34 µm) long; crest height 3–6 µm (average 4 µm).
Comparison: Differs from E. rugulosum by possessing ridges that are topped by membranes. Protoellipsodinium spinocristatum Davey et Verdier, 1971 is more elongate in shape and has small spines that arise from the ridges which are not fused together.
Range: Middle Coniacian (M. coranguinum Zone) — top upper Santonian (Marsupites Zone), east Kent. Middle Santonian (M. coranguinum Zone) — lower Campanian (O. pilula Zone), Whitecliff, Isle of Wight.
Heterosphaeridium cf. cordiforme Yun, 1981
Comparison: Differs from H. cordiforme by the thicker central body, generally of a slightly larger size, longer processes and a greater number of the complex interconnecting processes. Heterosphaeridium spinaconjunctum has a smaller number of the simple processes, and more of the complex, interconnecting processes. Heterosphaeridium verdieri has distinctive, isolated V-shaped processes which H. cf. verdieri lacks.
Dimensions: Range of 4 measured specimens: central body 54– 62 µm (average 59 µm) wide × 44–64 µm (average 52 µm) long; maximum process length 10–22 µm (average 15 µm).
Holotype: Prince et al., 2008, pl.1, figs.4–6.
Age: late Santonian.
Original description (Prince et al., 2008):
Ellipsodinium membraniferum Prince, Jarvis, Pearce et Tocher, sp. nov. (Plate I, 4–6)
Holotype: Slide PRC 3964, WCI 117, E/F ref. W38/1, Whitecliff, Isle of Wight, England.
Paratype: Slide PRC 2761, FNP 6(2), E/F ref. P21/4, Foreness Point, east Kent, England.
Repository: Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Wales, UK.
Type locality: Whitecliff, Isle of Wight, England.
Stratigraphic horizon: Lower upper Santonian, upper U. socialis Zone.
Etymology: Membraniferum, with reference to the membranes that form the distinctive ridges.
Diagnosis: A round to slightly oval cyst which has longitudinal anastomosing ridges which are topped by membranes that have an irregular edge.
Description: Cyst round to slightly oval in shape, bearing longitudinal anastomosing ridges. The paracingulum is sometimes indicated by a single transverse ridge. All the ridges are topped by a membrane which forms a crest up to 6 µm high. This crest has a highly irregular edge and when viewed normal to the cyst surface gives the ridges a wavy appearance. The crests appear to be formed by the fusing of acicular spines which gives the crest a very irregular edge. The archaeopyle is precingular, type P. With the exception of the archaeopyle and the paracingulum (where present), no paratabulation is indicated.
Dimensions: Holotype: overall 24 µm wide × 36 µm long; crest height 4 µm. Range of 11 measured specimens: overall 24– 36 µm (average 29 µm) wide × 26–37 µm (average 34 µm) long; crest height 3–6 µm (average 4 µm).
Comparison: Differs from E. rugulosum by possessing ridges that are topped by membranes. Protoellipsodinium spinocristatum Davey et Verdier, 1971 is more elongate in shape and has small spines that arise from the ridges which are not fused together.
Range: Middle Coniacian (M. coranguinum Zone) — top upper Santonian (Marsupites Zone), east Kent. Middle Santonian (M. coranguinum Zone) — lower Campanian (O. pilula Zone), Whitecliff, Isle of Wight.
Heterosphaeridium cf. cordiforme Yun, 1981
Comparison: Differs from H. cordiforme by the thicker central body, generally of a slightly larger size, longer processes and a greater number of the complex interconnecting processes. Heterosphaeridium spinaconjunctum has a smaller number of the simple processes, and more of the complex, interconnecting processes. Heterosphaeridium verdieri has distinctive, isolated V-shaped processes which H. cf. verdieri lacks.
Dimensions: Range of 4 measured specimens: central body 54– 62 µm (average 59 µm) wide × 44–64 µm (average 52 µm) long; maximum process length 10–22 µm (average 15 µm).