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Spiniferites ramosus ssp. aquilus
Spiniferites ramosus subsp. aquilus Pearce, 2010, p.56, pl.7, figs.7–12.
Pearce (2010, p.56) gave the heading for this taxon as "Spiniferites ramosus aquilus sp. nov." and began the diagnosis with "A species of Spiniferites ...". It is clear form the name, however, that he intended the taxon to be a subspecies, and so we consider the incorrect citation of rank as a typographic error and consider Spiniferites ramosus subsp. aquilus to be validly published in Pearce (2010).
Holotype: Pearce, 2010, pl.7, figs.7–12.
Type locality and horizon. Trunch borehole, Norfolk, UK; 415.9–416.0 m, Burnham–Flamborough Chalk (undifferentiated), high Micraster cortestudinarium Zone (high lower Coniacian).
Age: early Cenomanian–late Campanian.
Diagnosis. A species of Spiniferites possessing a densely and minutely reticulate periphragm imparting a distinctively dark aspect under transmitted light microscopy.
Description. Small to medium-sized spiniferate chorate dinoflagellate. The central body episome is prolate ellipsoid and the hyposome is roughly spherical to minorly oblate ellipsoid. Wall two-layered, comprised of a thin endophragm (~0.5 μm), which is very finely reticulate such that the wall appears blackish under transmitted light microscopy. The periphragm is thin (~0.5 μm) and smooth from where hollow (at least proximally) processes are developed. The processes are short (~10 μm long), gonal and trifurcate distally (3–4 μm in length) terminating in a minute (<1 μm long) bifurcation. The processes are united proximally by well-developed parasutural crests that are highest against the gonal processes and up to 4 μm in between; clearly delineating the standard gonyaulacacean paratabulation. The paracingulum is distinctly laevorotatory by over twice the width of the paracingulum; the parasulcus is straight and lacking clearly delineated paraplates other than the posterior sulcal paraplate. The sixth precingular paraplate is distinctly triangular with a rectilinear contact with the apical series. The archaeopyle is precingular (Type 1P, operculum detached) and formed by the loss of the third precingular paraplate (3").
Comparison. Differs from Spiniferites ramosus reticulatus (Davey & Williams 1966a: 38, pl. 1, figs 2–3) Lentin &Williams, 1973 by possessing a more finely reticulate endophragm that results in a distinctively darkened aspect and a paratabulation clearly demarcated by the smooth parasutural crests.
Pearce (2010, p.56) gave the heading for this taxon as "Spiniferites ramosus aquilus sp. nov." and began the diagnosis with "A species of Spiniferites ...". It is clear form the name, however, that he intended the taxon to be a subspecies, and so we consider the incorrect citation of rank as a typographic error and consider Spiniferites ramosus subsp. aquilus to be validly published in Pearce (2010).
Holotype: Pearce, 2010, pl.7, figs.7–12.
Type locality and horizon. Trunch borehole, Norfolk, UK; 415.9–416.0 m, Burnham–Flamborough Chalk (undifferentiated), high Micraster cortestudinarium Zone (high lower Coniacian).
Age: early Cenomanian–late Campanian.
Diagnosis. A species of Spiniferites possessing a densely and minutely reticulate periphragm imparting a distinctively dark aspect under transmitted light microscopy.
Description. Small to medium-sized spiniferate chorate dinoflagellate. The central body episome is prolate ellipsoid and the hyposome is roughly spherical to minorly oblate ellipsoid. Wall two-layered, comprised of a thin endophragm (~0.5 μm), which is very finely reticulate such that the wall appears blackish under transmitted light microscopy. The periphragm is thin (~0.5 μm) and smooth from where hollow (at least proximally) processes are developed. The processes are short (~10 μm long), gonal and trifurcate distally (3–4 μm in length) terminating in a minute (<1 μm long) bifurcation. The processes are united proximally by well-developed parasutural crests that are highest against the gonal processes and up to 4 μm in between; clearly delineating the standard gonyaulacacean paratabulation. The paracingulum is distinctly laevorotatory by over twice the width of the paracingulum; the parasulcus is straight and lacking clearly delineated paraplates other than the posterior sulcal paraplate. The sixth precingular paraplate is distinctly triangular with a rectilinear contact with the apical series. The archaeopyle is precingular (Type 1P, operculum detached) and formed by the loss of the third precingular paraplate (3").
Comparison. Differs from Spiniferites ramosus reticulatus (Davey & Williams 1966a: 38, pl. 1, figs 2–3) Lentin &Williams, 1973 by possessing a more finely reticulate endophragm that results in a distinctively darkened aspect and a paratabulation clearly demarcated by the smooth parasutural crests.