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Pilosidinium cactosum
Pilosidinium cactosum Quattrocchio and Sarjeant, 1992, p.91–92 (al. 2–243 — 2–244), pl.6, fig.2, pl.8, fig.6. Holotype: Quattrocchio and Sarjeant, 1992, pl.6, fig.2. Age: middle-late Tithonian.
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Original description: [Quattrocchio and Sarjeant, 1992]:
Pilosidinium cactosum Quattrocchio and Sarjeant, sp. nov.
(Plate 6, Fig. 2; Plate 8, Fig. 6)
1979 Sentusidinium sp. D- Fensome, p. 18-
19, pl. 2 fig. 3, text-fig. 7a.
Derivatio nominis. Gr., kaktos, a prickly plant: in reference to the array of spines.
Diagnosis. Cyst proximate, apteate, cryptotabulate. Ambitus subspherical, composed of autophragm only. Phragma psilate, bearing a great
variety of nontabular processes, densely and evenly distributed; these range from verrucae and tuberculae to spines with acuminate, capitate, buccinate, flared or briefly bifurcate distal endings. Archaeopyle apical. Principal archaeopyle suture zig-zag; short, longitudinal accessory sutures denote the anterior boundaries between six precingular and four apical paraplates; the paratabulation is otherwise not indicated.
Illustrated specimens. Holotype: 2969/4: 19,8/104,5 (Plate 7,Fig. 2); SEM specimen from horizon 2969 (Plate 9, Fig. 6).
Lodgement. Palynological Laboratory, Universidad Nacional del Sur, Bahia Blanca.
Dimensions. Holotype: overall length 34μm, breadth 32 μm. Range: overall length (with operculum) 33-34 μm (2 specimens measured),
(without operculum) 25-36 μm (16 specimens measured), breadth 25-32 u m, length of spines up to 2 μm.
Remarks. This morphotype was first reported by Fensome (1979) from the Upper Jurassic Hareelv Formation of Jameson Land, Kalaallit Nunaat (formerly Greenland). A specific name is given here because the occurrence of specimens of identical morphology in the Jurassic of the Neuquén Basin shows this to be a type widely distributed and of potential biostratigraphical importance. The Argentinian specimens are smaller than those from Kalaallit Nunaat (length including operculum 58 μm, length excluding operculum 41 μm, breadth 45 μm), but comparable in all
other respects. The size difference is not considered important, especially since it has been observed previously that Southern hemisphere forms of species known also from northwest Europe are frequently much larger.
This species resembles Pilosidinium fensomei Courtinat, 1989, in the density and length of its spines but differs in their much greater variety of form.
------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Quattrocchio and Sarjeant, 1992]:
Pilosidinium cactosum Quattrocchio and Sarjeant, sp. nov.
(Plate 6, Fig. 2; Plate 8, Fig. 6)
1979 Sentusidinium sp. D- Fensome, p. 18-
19, pl. 2 fig. 3, text-fig. 7a.
Derivatio nominis. Gr., kaktos, a prickly plant: in reference to the array of spines.
Diagnosis. Cyst proximate, apteate, cryptotabulate. Ambitus subspherical, composed of autophragm only. Phragma psilate, bearing a great
variety of nontabular processes, densely and evenly distributed; these range from verrucae and tuberculae to spines with acuminate, capitate, buccinate, flared or briefly bifurcate distal endings. Archaeopyle apical. Principal archaeopyle suture zig-zag; short, longitudinal accessory sutures denote the anterior boundaries between six precingular and four apical paraplates; the paratabulation is otherwise not indicated.
Illustrated specimens. Holotype: 2969/4: 19,8/104,5 (Plate 7,Fig. 2); SEM specimen from horizon 2969 (Plate 9, Fig. 6).
Lodgement. Palynological Laboratory, Universidad Nacional del Sur, Bahia Blanca.
Dimensions. Holotype: overall length 34μm, breadth 32 μm. Range: overall length (with operculum) 33-34 μm (2 specimens measured),
(without operculum) 25-36 μm (16 specimens measured), breadth 25-32 u m, length of spines up to 2 μm.
Remarks. This morphotype was first reported by Fensome (1979) from the Upper Jurassic Hareelv Formation of Jameson Land, Kalaallit Nunaat (formerly Greenland). A specific name is given here because the occurrence of specimens of identical morphology in the Jurassic of the Neuquén Basin shows this to be a type widely distributed and of potential biostratigraphical importance. The Argentinian specimens are smaller than those from Kalaallit Nunaat (length including operculum 58 μm, length excluding operculum 41 μm, breadth 45 μm), but comparable in all
other respects. The size difference is not considered important, especially since it has been observed previously that Southern hemisphere forms of species known also from northwest Europe are frequently much larger.
This species resembles Pilosidinium fensomei Courtinat, 1989, in the density and length of its spines but differs in their much greater variety of form.