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Parvocysta nasuta
Parvocysta nasuta Bjaerke, 1980, p.65–66, pl.1, figs.11–12; text-fig.3A. Emendation: Below, 1987a, p.139, as Reutlingia nasuta.
Originally (and now) Parvocysta, subsequently Reutlingia. Below, 1987 transferred this species to Reutlingia Drugg, 1978; however, Lentin and Williams, 1989 retained it in Parvocysta. At the time of the transfer to Reutlingia, Below, 1987 emended the diagnosis of this species.
Holotype: Bjµrke, 1980, pl.1, figs.11,12
Locus typicus: Knorringfjellet, Spitsbergen
Stratum typicum: Toarcian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Below (1987a, p139) emended diagnosis:
Arrangement of plates on the dinoflagellate amphiesma cop, pop, cap, 5', 3a, 7"-6", 7c, 5"’, 2"”, as, y, z, ps: 1"” and 2"” located symmetrically on either side of the dorsoventral plane; large ps omegaform. Cyst form proximate, acavate to finicavate, elongate peridinioid, epicyst with pointed coniform extension into apical horn and large, wing-like projections at the cingulum, cingulum deeply constricted towards the epicyst, fused with the hypocyst in the region of the postcingular series to form a hyperboloid unit, sulcus broad, antapex rounded, equatorial cross-section oval to reniform; size small; composed of pedium and luxuria, luxuria only occasionally spreading as a tectum over 1"”, pedium smooth, folded into carinate, distally smooth ribs along longitudinally oriented fines and those bounding the antapical areae and along the anterior margin of the cingulum, so that the areation is indicated, but exact contours of areae are usually not discernible. Fastigiate 2a. Cingulum weakly helicoidal laevorotatory without posterior boundaries, pseudoareate; archeopyle anterior intercalary, 2a; operculum monoareate, adnate to precingulars, opercular formula 2a. Size length 31-43 µm, width 20-28 µm.
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Original diagnosis: Bjµrke, 1980, p. 65
Dinoflagellate cysts of the genus Parvocysta with an elongated pentagonal outline. Epicyst narrowing into a prominent blunt apical horn, antapical area slightly concave to convex. Cyst wall smooth. Paracingulum indicated by a shallow to relatively deep constriction separating the cyst into an elongated epicyst and a short hypocyst.
Size: 31-43 µm long, 20-28 µm wide.
Original description: Bjµrke, 1980, p. 66
Small dinoflagellate cysts with an elongated pentagonal outline. Epicyst narrowing into a prominent apical horn, antapical area slightly concave to convex.
Cyst wall: single layered, smooth. Longitudinal folds common.
Paratabulation: except for archeopyle not observed.
Archeopyle: intercalary, outline hexagonal with posterior and anterior angulations (geniculate), formed by one mid-dorsal intercalary paraplate.
Paracingulum: indicated by a shallow to deep depression.
Affinities: Bjµrke, 1980, p. 66:
P. nasuta is similar to P. bullula, P. contracta, and P. barbata but differs from these by the smooth surface and the prominent apical horn.
Remarks: Poulsen 1996, p. 85:
In the type material, this species was described as being elongate pentagonal. The Danish specimens vary in shape from elongate pentagonal to pentagonal and subspherical/subpentagonal. All specimens, however, have a psilate surface.
Recorded occurrence: Denmark: Parvocysta nasuta Subzone, Mancodinium semitabulatum Zone.
Originally (and now) Parvocysta, subsequently Reutlingia. Below, 1987 transferred this species to Reutlingia Drugg, 1978; however, Lentin and Williams, 1989 retained it in Parvocysta. At the time of the transfer to Reutlingia, Below, 1987 emended the diagnosis of this species.
Holotype: Bjµrke, 1980, pl.1, figs.11,12
Locus typicus: Knorringfjellet, Spitsbergen
Stratum typicum: Toarcian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Below (1987a, p139) emended diagnosis:
Arrangement of plates on the dinoflagellate amphiesma cop, pop, cap, 5', 3a, 7"-6", 7c, 5"’, 2"”, as, y, z, ps: 1"” and 2"” located symmetrically on either side of the dorsoventral plane; large ps omegaform. Cyst form proximate, acavate to finicavate, elongate peridinioid, epicyst with pointed coniform extension into apical horn and large, wing-like projections at the cingulum, cingulum deeply constricted towards the epicyst, fused with the hypocyst in the region of the postcingular series to form a hyperboloid unit, sulcus broad, antapex rounded, equatorial cross-section oval to reniform; size small; composed of pedium and luxuria, luxuria only occasionally spreading as a tectum over 1"”, pedium smooth, folded into carinate, distally smooth ribs along longitudinally oriented fines and those bounding the antapical areae and along the anterior margin of the cingulum, so that the areation is indicated, but exact contours of areae are usually not discernible. Fastigiate 2a. Cingulum weakly helicoidal laevorotatory without posterior boundaries, pseudoareate; archeopyle anterior intercalary, 2a; operculum monoareate, adnate to precingulars, opercular formula 2a. Size length 31-43 µm, width 20-28 µm.
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Original diagnosis: Bjµrke, 1980, p. 65
Dinoflagellate cysts of the genus Parvocysta with an elongated pentagonal outline. Epicyst narrowing into a prominent blunt apical horn, antapical area slightly concave to convex. Cyst wall smooth. Paracingulum indicated by a shallow to relatively deep constriction separating the cyst into an elongated epicyst and a short hypocyst.
Size: 31-43 µm long, 20-28 µm wide.
Original description: Bjµrke, 1980, p. 66
Small dinoflagellate cysts with an elongated pentagonal outline. Epicyst narrowing into a prominent apical horn, antapical area slightly concave to convex.
Cyst wall: single layered, smooth. Longitudinal folds common.
Paratabulation: except for archeopyle not observed.
Archeopyle: intercalary, outline hexagonal with posterior and anterior angulations (geniculate), formed by one mid-dorsal intercalary paraplate.
Paracingulum: indicated by a shallow to deep depression.
Affinities: Bjµrke, 1980, p. 66:
P. nasuta is similar to P. bullula, P. contracta, and P. barbata but differs from these by the smooth surface and the prominent apical horn.
Remarks: Poulsen 1996, p. 85:
In the type material, this species was described as being elongate pentagonal. The Danish specimens vary in shape from elongate pentagonal to pentagonal and subspherical/subpentagonal. All specimens, however, have a psilate surface.
Recorded occurrence: Denmark: Parvocysta nasuta Subzone, Mancodinium semitabulatum Zone.