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Sentusidinium spinosum
Sentusidinium spinosum sp. nov., Pearce, M. A., 2018, p. 82
Holotype: Pearce, M. A., 2018, Pl. 5, figs. 1–6.
Type locality and horizon: Upper Chalk Formation, St. Margaret’s Chalk Member, Sternotaxis plana Zone
Stratigraphic range: Middle Turonian to Middle Coniacian
Original description: Pearce, M. A., 2018:
Diagnosis:
A species of Sentusidinium with an even covering of relatively long, flexuous and acuminate spines.
Description:
A medium-sized proximate dinoflagellate cyst with a sub-rounded body.
Wall: composed of a micro-reticulate autophragm that possesses relatively long (4–16 μm), evenly distributed, hollow spines with simple acuminate tips.
No expression of the cingulum or sulcus is present.
Archaeopyle: apical, Type tA, with a zig-zag margin and clear accessory sutures.
Operculum: may be attached but more usually detached.
Dimensions:
Holotype, central body w/ l = 61 × 48 μm, maximum process length = 11 μm.
Range, central body w/ l = 46(56)72 × 30(46)56 μm, maximum processes length = 4(6)16 μm.
Twenty specimens measured.
Affinities/Comparison:
Sentusidinium aptiense (Burger, 1980a) Burger, 1980b also possesses hollow spines but which differ from S. spinosum sp. nov. in their relatively shorter length of 3–4 μm. These species also have mutually exclusive ranges, being Callovian to Aptian for S. aptiense (Wood et al., 2015) and Turonian for S. spinosum sp. nov. Sentusidinium densicomatum (Maier, 1959) Sarjeant, 1983 differs in possessing more densely distributed hair-like projections. The processes are also much more numerous on S. Pilosum (Ehrenberg, 1854) Sarjeant and Stover, 1978 and which also have variable tips. Spine length is comparable on S. sahii (Khanna and Singh, 1981) Wood et al., 2016 and S. seperatum (McIntyre and Brideaux, 1980) Lentin and Williams, 1981 but which also have variable tips in the former and bifid and branched tips in the latter.
Holotype: Pearce, M. A., 2018, Pl. 5, figs. 1–6.
Type locality and horizon: Upper Chalk Formation, St. Margaret’s Chalk Member, Sternotaxis plana Zone
Stratigraphic range: Middle Turonian to Middle Coniacian
Original description: Pearce, M. A., 2018:
Diagnosis:
A species of Sentusidinium with an even covering of relatively long, flexuous and acuminate spines.
Description:
A medium-sized proximate dinoflagellate cyst with a sub-rounded body.
Wall: composed of a micro-reticulate autophragm that possesses relatively long (4–16 μm), evenly distributed, hollow spines with simple acuminate tips.
No expression of the cingulum or sulcus is present.
Archaeopyle: apical, Type tA, with a zig-zag margin and clear accessory sutures.
Operculum: may be attached but more usually detached.
Dimensions:
Holotype, central body w/ l = 61 × 48 μm, maximum process length = 11 μm.
Range, central body w/ l = 46(56)72 × 30(46)56 μm, maximum processes length = 4(6)16 μm.
Twenty specimens measured.
Affinities/Comparison:
Sentusidinium aptiense (Burger, 1980a) Burger, 1980b also possesses hollow spines but which differ from S. spinosum sp. nov. in their relatively shorter length of 3–4 μm. These species also have mutually exclusive ranges, being Callovian to Aptian for S. aptiense (Wood et al., 2015) and Turonian for S. spinosum sp. nov. Sentusidinium densicomatum (Maier, 1959) Sarjeant, 1983 differs in possessing more densely distributed hair-like projections. The processes are also much more numerous on S. Pilosum (Ehrenberg, 1854) Sarjeant and Stover, 1978 and which also have variable tips. Spine length is comparable on S. sahii (Khanna and Singh, 1981) Wood et al., 2016 and S. seperatum (McIntyre and Brideaux, 1980) Lentin and Williams, 1981 but which also have variable tips in the former and bifid and branched tips in the latter.