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Vozzhennikovia netrona
Vozzhennikovia netrona Levy and Harwood, 2000, p.210,212, pl.11, figs.f–g. Emendation: Sluijs et al., 2009, p.49.
Holotype: Levy and Harwood, 2000, pl.11, figs.f–g.
Age: middle-late Eocene.
Original description (Levy and Harwood, 2000):
Vozzhennikovia netrona n. sp. Plate 11, figs. f and g
Vozzhennikovia apertura (Wilson) sensu Mohr, 1990, Plate 6, Figure 10.
Vozzhennikovia sp. a Crouch & Hollis, 1996, Plate 7, Figure 9.
Derivation of name. Greek, netron, spindle; with reference to the spindle-like shape.
Holotype. Plate 11, Figures f-g. UNSM PB99-09 Sample E 303(1), slide 4, middle to upper Eocene erratic, McMurdo Sound, Antarctica.
Description. Shape: Pericyst sub-polygonal with long apical and left antapical horns. The lateral margins of the epipericyst and hypopericyst are typically straighto slightly convex. Phragma: A smooth endophragm is closely appressed to the periphragm except in the apical and antapical regions. The surface of the periphragm is covered with short (2/a) capitate? spines which have a non-tabular distribution. Paratabulation: Peridinioid, indicated by the intercalary archeopyle. Paracingulum: Indicated by parasutural ridges that encircle the cyst in the adcingularegion. The distal margins of the parasutural ridges possess capitate spines. Non-tabular spines occur within the paracingulum. The paracingulum is laevorotatory, offset by Parasulcus: Indicated by a break in the paracingulum. Posterior of the paracingulum, a depression in the surface of the cyst delineates the parasulcus. This depression has reduced surface ornamentation. Archeopyle: Type I, hexa deltaform, formed by the complete removal of the 2a paraplate.
Dimensions. Observed range (six specimens)' pericyst length - 61 to 85 µ (mean 72 µ), pericyst width - 44 to 31 µ (mean 40 µ), apical horn length - 14 to 20 µ (mean 17 µ), antapical horn length - 12 to 20 µ (mean 16 µ).
Comments/comparison. Possession of long apical and left antapical horns and a polygonal pericystal outline characterize this taxon. Otherwise, the species is similar to Vozzhennikovia apertura. This species was illustrated by Crouch and Hollis (1996), however, no description was given. Mohr (1990) recovered this taxon from ODP Hole 696 but assigned it to Vozzhennikovia apertura.
Stratigraphic Range. The species occurs in the middle to upper Eocene of DSDP Leg 29, Site 281 (Crouch and Hollis, 1996) and the middle to upper Eocene of ODP Hole 696B (Mohr, 1990).
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Emendation (Sluijs et al. 2009):
Vozzhennikovia netrona Levy and Harwood, 2000, emend.
Holotype: Levy and Harwood, 2000, plate 11, f–g.
Diagnosis: A species of Vozzhennikovia with exceptionally long apical and left antapical horns.
Emended description: Cornucavate, proximate, ovoidal, dorso-ventrally compressed peridiniacean cysts with long apical and left antapical horns, which are approximately 1/3rd of the length of the central body. Pericyst bearing numerous uniformly distributed to proximosutural capitate spines, which may form intratabular clusters or are penitabular. The cingulum is indented and delineated by a row of spines. Sulcus indented, extending onto the epicyst but longer and wider on the hypocyst. The archeopyle is type I or 3I, with the operculum usually being detached.
Discussion: Vozzhennikovia netrona differs from other species of the genus by having long apical and left antapical horns, which are approximately 1/3rd of the length of the central body. Dimensions: Range: length 61(72)85 μm, breadth 31(40)44 μm, apical horn length 14(27)20 μm, left antapical horn length 12(16)20 μm, based on 6 specimens (Levy and Harwood, 2000). Stratigraphic occurrence: Mid to Late Eocene of the Southern Ocean (Plate VI).
Holotype: Levy and Harwood, 2000, pl.11, figs.f–g.
Age: middle-late Eocene.
Original description (Levy and Harwood, 2000):
Vozzhennikovia netrona n. sp. Plate 11, figs. f and g
Vozzhennikovia apertura (Wilson) sensu Mohr, 1990, Plate 6, Figure 10.
Vozzhennikovia sp. a Crouch & Hollis, 1996, Plate 7, Figure 9.
Derivation of name. Greek, netron, spindle; with reference to the spindle-like shape.
Holotype. Plate 11, Figures f-g. UNSM PB99-09 Sample E 303(1), slide 4, middle to upper Eocene erratic, McMurdo Sound, Antarctica.
Description. Shape: Pericyst sub-polygonal with long apical and left antapical horns. The lateral margins of the epipericyst and hypopericyst are typically straighto slightly convex. Phragma: A smooth endophragm is closely appressed to the periphragm except in the apical and antapical regions. The surface of the periphragm is covered with short (2/a) capitate? spines which have a non-tabular distribution. Paratabulation: Peridinioid, indicated by the intercalary archeopyle. Paracingulum: Indicated by parasutural ridges that encircle the cyst in the adcingularegion. The distal margins of the parasutural ridges possess capitate spines. Non-tabular spines occur within the paracingulum. The paracingulum is laevorotatory, offset by Parasulcus: Indicated by a break in the paracingulum. Posterior of the paracingulum, a depression in the surface of the cyst delineates the parasulcus. This depression has reduced surface ornamentation. Archeopyle: Type I, hexa deltaform, formed by the complete removal of the 2a paraplate.
Dimensions. Observed range (six specimens)' pericyst length - 61 to 85 µ (mean 72 µ), pericyst width - 44 to 31 µ (mean 40 µ), apical horn length - 14 to 20 µ (mean 17 µ), antapical horn length - 12 to 20 µ (mean 16 µ).
Comments/comparison. Possession of long apical and left antapical horns and a polygonal pericystal outline characterize this taxon. Otherwise, the species is similar to Vozzhennikovia apertura. This species was illustrated by Crouch and Hollis (1996), however, no description was given. Mohr (1990) recovered this taxon from ODP Hole 696 but assigned it to Vozzhennikovia apertura.
Stratigraphic Range. The species occurs in the middle to upper Eocene of DSDP Leg 29, Site 281 (Crouch and Hollis, 1996) and the middle to upper Eocene of ODP Hole 696B (Mohr, 1990).
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Emendation (Sluijs et al. 2009):
Vozzhennikovia netrona Levy and Harwood, 2000, emend.
Holotype: Levy and Harwood, 2000, plate 11, f–g.
Diagnosis: A species of Vozzhennikovia with exceptionally long apical and left antapical horns.
Emended description: Cornucavate, proximate, ovoidal, dorso-ventrally compressed peridiniacean cysts with long apical and left antapical horns, which are approximately 1/3rd of the length of the central body. Pericyst bearing numerous uniformly distributed to proximosutural capitate spines, which may form intratabular clusters or are penitabular. The cingulum is indented and delineated by a row of spines. Sulcus indented, extending onto the epicyst but longer and wider on the hypocyst. The archeopyle is type I or 3I, with the operculum usually being detached.
Discussion: Vozzhennikovia netrona differs from other species of the genus by having long apical and left antapical horns, which are approximately 1/3rd of the length of the central body. Dimensions: Range: length 61(72)85 μm, breadth 31(40)44 μm, apical horn length 14(27)20 μm, left antapical horn length 12(16)20 μm, based on 6 specimens (Levy and Harwood, 2000). Stratigraphic occurrence: Mid to Late Eocene of the Southern Ocean (Plate VI).