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Sentusidinium fibrillosum
Sentusidinium? fibrillosum Backhouse, 1988
Backhouse, 1988 questionably included this species in Sentusidinium.
Holotype: Backhouse, 1988, pl.41, figs.4a-b
Locus typicus: Perth Basin, Western Australia
Stratum typicum: Late Valanginian-Hauterivian
Original description: Backhouse, 1988, p.107
Small, ovoid, proximochorate cysts, without a preferred orientation. Small, offset antapical horn on some specimens. Autopragm less than 1 µm thick, composed of numerous fine interlocking fibres, bearing numerous fine, fibrous, truncate processes up to 3 µm high. Fibres of processes continuous with fibres of cyst wall. Paracingulum 4 to 6 µm wide, offset approximately 5 µm, expressed by transverse ridges, not subdivided. Other parasutural features absent. Archeopyle apical, type [tA], operculum free. Six precingular paraplates delineated by primary archeopyle suture and accessory sutures.
Dimensions: Length of holotype without operculum 39 µm, width 46 µm. Range of Length without operculum (10 specimens) 29(35)39 µm, width 29(39)46 µm. Total Iength of 2 specimens 46 and 47 µm.
Affinities:
Backhouse, 1988, p.107: Because it is a subspherical cyst bearing evenly distributed nontabular processes this species is provisionally assigned to Sentusidinium, although the development of paracingular ridges strictly excludes it from this genus. Other species of Sentusidinium do not possess a fibrous autophragm, or fibrous spines: this suggests that fibrilloslon belongs in a different cyst lineage from other cysts currently included in Sentusidinium.
Backhouse, 1988 questionably included this species in Sentusidinium.
Holotype: Backhouse, 1988, pl.41, figs.4a-b
Locus typicus: Perth Basin, Western Australia
Stratum typicum: Late Valanginian-Hauterivian
Original description: Backhouse, 1988, p.107
Small, ovoid, proximochorate cysts, without a preferred orientation. Small, offset antapical horn on some specimens. Autopragm less than 1 µm thick, composed of numerous fine interlocking fibres, bearing numerous fine, fibrous, truncate processes up to 3 µm high. Fibres of processes continuous with fibres of cyst wall. Paracingulum 4 to 6 µm wide, offset approximately 5 µm, expressed by transverse ridges, not subdivided. Other parasutural features absent. Archeopyle apical, type [tA], operculum free. Six precingular paraplates delineated by primary archeopyle suture and accessory sutures.
Dimensions: Length of holotype without operculum 39 µm, width 46 µm. Range of Length without operculum (10 specimens) 29(35)39 µm, width 29(39)46 µm. Total Iength of 2 specimens 46 and 47 µm.
Affinities:
Backhouse, 1988, p.107: Because it is a subspherical cyst bearing evenly distributed nontabular processes this species is provisionally assigned to Sentusidinium, although the development of paracingular ridges strictly excludes it from this genus. Other species of Sentusidinium do not possess a fibrous autophragm, or fibrous spines: this suggests that fibrilloslon belongs in a different cyst lineage from other cysts currently included in Sentusidinium.