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Senoniasphaera protrusa subsp. congrensa
Senoniasphaera protrusa subsp. congrensa Prince et al., 2008, p.90, pl.2, figs.1–3.
Holotype: Prince et al., 2008, pl.2, figs.1–2.
Age: middle Santonian–early Campanian.
Original description (Prince et al., 2008):
Senoniasphaera protrusa Clarke et Verdier, 1967 emend Prince et al., 1999 congrensa Prince, Jarvis, Pearce et Tocher subsp. nov. ( Plate II, 1–3)
1990 Senoniasphaera rotundata Clarke et Verdier, 1967; Harker et al.; pl. 11, their Figs. 10, 13? only (Campanian; Western Interior, North America).
Holotype: Slide PRC2762.2, sample FNP 7(2), E/F ref. U15/2.
Repository: Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Wales, UK.
Type locality: Foreness Point, east Kent, England.
Stratigraphic horizon: Uppermost upper Santonian, collected 1 m below the top of the Marsupites Zone.
Etymology: Latin, congrens, symmetrical, with reference to the symmetrical inner body.
Diagnosis: An elongate subspecies of Senoniasphaera protrusa in which the inner body is oval with a slight antapical protuberance on the centre line so that the inner body is vertically symmetrical.
Dimensions: Holotype: inner body 40 µm wide × 52 µm long, outer body 54 µm wide × 62 µm long. Range of 43 measured specimens: inner body 20–59 µm (average 41 µm) wide × 34–62 µm (average 47 µm) long; outer body 36–80 µm (average 60 µm) wide × 26–108 µm (average 64 µm) long.
Description: Inner body round to oval with a slight antapical protuberance at the antapex so that the inner body is vertically symmetrical. The inner body is connected to the outer body by a small number of pillars that narrow towards their mid-point and broaden towards their distal extremity. Between the pillars, a few rounded cavities exist.
The outer body has two antapical horns of unequal size, the left usually being the larger, although in some cases only one horn is visible. The outer body has an ornament ranging from finely to coarsely reticulate whereas the inner is smooth to finely reticulate. Paratabulation is indicated by bands of concentrated ornament on the dorsal surface only, where three pre- and three postcingular plates are usually visible. In some cases, where the cyst is finely reticulate all over, the parasutural bands are more difficult to see. In all cases, the cyst outline appears smooth and wavy. The archaeopyle is apical, type tA, usually detached with a well developed zigzag margin and offset sulcul notch.
Comparison: Differs from all other forms of Senoniasphaera by the vertically symmetrical shape of the inner body. The two most similar species are S. protrusa and Senoniasphaera macroreticulata. Senoniasphaera protrusa has an inner body that has two antapical horns of unequal size, giving the inner body an asymmetrical shape. Senoniasphaera macroreticulata ( Plate I, 7–11) has distinctive pillars that are elongate, slender or broad, perforate and fibrous. The cavities between these pillars have an irregular shape.
Stratigraphic range: Middle Santonian (upper M. coranguinum Zone) to section top (lower Campanian, O. pilula Zone).
Holotype: Prince et al., 2008, pl.2, figs.1–2.
Age: middle Santonian–early Campanian.
Original description (Prince et al., 2008):
Senoniasphaera protrusa Clarke et Verdier, 1967 emend Prince et al., 1999 congrensa Prince, Jarvis, Pearce et Tocher subsp. nov. ( Plate II, 1–3)
1990 Senoniasphaera rotundata Clarke et Verdier, 1967; Harker et al.; pl. 11, their Figs. 10, 13? only (Campanian; Western Interior, North America).
Holotype: Slide PRC2762.2, sample FNP 7(2), E/F ref. U15/2.
Repository: Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, Wales, UK.
Type locality: Foreness Point, east Kent, England.
Stratigraphic horizon: Uppermost upper Santonian, collected 1 m below the top of the Marsupites Zone.
Etymology: Latin, congrens, symmetrical, with reference to the symmetrical inner body.
Diagnosis: An elongate subspecies of Senoniasphaera protrusa in which the inner body is oval with a slight antapical protuberance on the centre line so that the inner body is vertically symmetrical.
Dimensions: Holotype: inner body 40 µm wide × 52 µm long, outer body 54 µm wide × 62 µm long. Range of 43 measured specimens: inner body 20–59 µm (average 41 µm) wide × 34–62 µm (average 47 µm) long; outer body 36–80 µm (average 60 µm) wide × 26–108 µm (average 64 µm) long.
Description: Inner body round to oval with a slight antapical protuberance at the antapex so that the inner body is vertically symmetrical. The inner body is connected to the outer body by a small number of pillars that narrow towards their mid-point and broaden towards their distal extremity. Between the pillars, a few rounded cavities exist.
The outer body has two antapical horns of unequal size, the left usually being the larger, although in some cases only one horn is visible. The outer body has an ornament ranging from finely to coarsely reticulate whereas the inner is smooth to finely reticulate. Paratabulation is indicated by bands of concentrated ornament on the dorsal surface only, where three pre- and three postcingular plates are usually visible. In some cases, where the cyst is finely reticulate all over, the parasutural bands are more difficult to see. In all cases, the cyst outline appears smooth and wavy. The archaeopyle is apical, type tA, usually detached with a well developed zigzag margin and offset sulcul notch.
Comparison: Differs from all other forms of Senoniasphaera by the vertically symmetrical shape of the inner body. The two most similar species are S. protrusa and Senoniasphaera macroreticulata. Senoniasphaera protrusa has an inner body that has two antapical horns of unequal size, giving the inner body an asymmetrical shape. Senoniasphaera macroreticulata ( Plate I, 7–11) has distinctive pillars that are elongate, slender or broad, perforate and fibrous. The cavities between these pillars have an irregular shape.
Stratigraphic range: Middle Santonian (upper M. coranguinum Zone) to section top (lower Campanian, O. pilula Zone).