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Vozzhennikovia tawanuiensis
From Fensome et al., 2019:
Vozzhennikovia tawanuiensis Crouch et al., 2014, p.65,71,73, pl.3, figs.1–12.
Holotype: Crouch et al., 2014, pl.3, figs.1–2.
Age: late Paleocene.
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Original description (Crouch et al., 2014):
Vozzhennikovia tawanuiensis Crouch et al., sp. nov. Plate III
Holotype: Sample U24/f960 (Slide SM4839), England Finder co-ordinate L36/0; Plate III, 1–2.
Paratype: Sample U24/f960 (Slide SM4840), England Finder co-ordinate H36/0; Plate III, 3.
Repository: The palynological type collection, GNS Science, Lower Hutt, New Zealand.
Type locality: Wanstead Formation; Tawanui section, Akitio River, southern Hawkes Bay, New Zealand; grid reference NZMS 260-U24/ 967 863.
Derivation of name: After Tawanui farm, where the type section is located.
Description: A proximate cyst of intermediate size, with a broad rounded apex and two very low antapical protrusions that taper into short horns. The left antapical horn can be slightly more developed than the right, although both antapical horns are short (up to 9 μm in specimens recorded). The apex lacks protrusion and horn. The cyst is cornucavate and the cavation is generally most obvious in the hypocyst near the base of the antapical horns. The epicyst and hypocyst are approximately the same size. The periphragm and endophragm are both thin and rounded to pentagonal in outline in dorso-ventral view. The periphragm is ornamented with short (up to 5 μm in specimens recorded), rod-like capitate processes that are closed distally. The processes are not densely arranged and ornamentation is non-tabular. The processes tend to be more common in the anterior and posterior regions, and also on the margins. The endophragm is difficult to delineate in most specimens. The archeopyle is an intercalary, Type I (2a paraplate), that can be obscure. The operculum is free but remains in position in some specimens.
Dimensions (in µm): Holotype - Range
Overall length: 58 - 52 (58) 71
Overall width: 61 - 50 (58) 70
Endocyst length: 51 - 47 (52) 65
Endocyst width: 56 - 46 (52) 64
Number of specimens measured: 12.
Stratigraphic occurrence: Late Paleocene (late Teurian). The LO of Vozzhennikovia tawanuiensis sp. nov. is in the lower part of NZDP8 and calcareous nannofossil Zone NP8, based on observations at Tawanui section. The LO is stratigraphically above the LO of Manumiella rotunda. Vozzhennikovia tawanuiensis sp. nov. has not been recorded in sediments younger than latest Paleocene and it appears to have a HO close to the Paleocene–Eocene boundary. At Tawanui, the HO is at 0.45 m (U24/f1023) below the P–E boundary (Crouch, 2001). Observed in mid-Waipara River, Tawanui, and Toi-Flat-1 core, along with Moeraki-Hampden and Measly Beach core in North Otago (Crouch, 2001). Rare to common in sections examined.
Remarks: Vozzhennikovia tawanuiensis sp. nov. is placed in the genus Vozzhennikovia Lentin and Williams, 1976, following discussion by Sluijs et al. (2009). They “retain Vozzhennikovia for peridiniacean dinocysts with an isodeltaform to isothetaform 2a, an archeopyle that can result from the loss of the 2a only or all three intercalary plates and a more or less uniform covering of spines of coni on the cyst that may or may not reflect tabulation”. Vozzhennikovia tawanuiensis sp. nov. differs from Vozzhennikovia angulata Wilson, 1988 in lacking a periphragm that is sharply angular in outline, in not having densely arranged processes, and in lacking an easily discernible paracingulum. It differs from Vozzhennikovia rotunda (Wilson, 1967) Lentin and Williams, 1976 in lacking development of an apical and left antapical horn, in having a less globular shape, and in lacking spinules in the paracingulum area. Vozzhennikovia tawanuiensis sp. nov. is distinguished from Spinidinium densispinatum Stanley, 1965 by lacking a distinct paracingulum, by having no evidence of sutural spines and by lacking a well-developed left antapical horn and apical horn. Some specimens of Vozzhennikovia tawanuiensis sp. nov. resemble rounded forms of Apectodinium homomorphum (Deflandre and Cookson, 1955) Lentin and Williams, 1977; however, the short rod-like capitate processes are distinctive for V. tawanuiensis sp. nov. and, furthermore, A. homomorphum has a more uniform distribution of processes and evidence of intratabular ornamentation.
Vozzhennikovia tawanuiensis Crouch et al., 2014, p.65,71,73, pl.3, figs.1–12.
Holotype: Crouch et al., 2014, pl.3, figs.1–2.
Age: late Paleocene.
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Original description (Crouch et al., 2014):
Vozzhennikovia tawanuiensis Crouch et al., sp. nov. Plate III
Holotype: Sample U24/f960 (Slide SM4839), England Finder co-ordinate L36/0; Plate III, 1–2.
Paratype: Sample U24/f960 (Slide SM4840), England Finder co-ordinate H36/0; Plate III, 3.
Repository: The palynological type collection, GNS Science, Lower Hutt, New Zealand.
Type locality: Wanstead Formation; Tawanui section, Akitio River, southern Hawkes Bay, New Zealand; grid reference NZMS 260-U24/ 967 863.
Derivation of name: After Tawanui farm, where the type section is located.
Description: A proximate cyst of intermediate size, with a broad rounded apex and two very low antapical protrusions that taper into short horns. The left antapical horn can be slightly more developed than the right, although both antapical horns are short (up to 9 μm in specimens recorded). The apex lacks protrusion and horn. The cyst is cornucavate and the cavation is generally most obvious in the hypocyst near the base of the antapical horns. The epicyst and hypocyst are approximately the same size. The periphragm and endophragm are both thin and rounded to pentagonal in outline in dorso-ventral view. The periphragm is ornamented with short (up to 5 μm in specimens recorded), rod-like capitate processes that are closed distally. The processes are not densely arranged and ornamentation is non-tabular. The processes tend to be more common in the anterior and posterior regions, and also on the margins. The endophragm is difficult to delineate in most specimens. The archeopyle is an intercalary, Type I (2a paraplate), that can be obscure. The operculum is free but remains in position in some specimens.
Dimensions (in µm): Holotype - Range
Overall length: 58 - 52 (58) 71
Overall width: 61 - 50 (58) 70
Endocyst length: 51 - 47 (52) 65
Endocyst width: 56 - 46 (52) 64
Number of specimens measured: 12.
Stratigraphic occurrence: Late Paleocene (late Teurian). The LO of Vozzhennikovia tawanuiensis sp. nov. is in the lower part of NZDP8 and calcareous nannofossil Zone NP8, based on observations at Tawanui section. The LO is stratigraphically above the LO of Manumiella rotunda. Vozzhennikovia tawanuiensis sp. nov. has not been recorded in sediments younger than latest Paleocene and it appears to have a HO close to the Paleocene–Eocene boundary. At Tawanui, the HO is at 0.45 m (U24/f1023) below the P–E boundary (Crouch, 2001). Observed in mid-Waipara River, Tawanui, and Toi-Flat-1 core, along with Moeraki-Hampden and Measly Beach core in North Otago (Crouch, 2001). Rare to common in sections examined.
Remarks: Vozzhennikovia tawanuiensis sp. nov. is placed in the genus Vozzhennikovia Lentin and Williams, 1976, following discussion by Sluijs et al. (2009). They “retain Vozzhennikovia for peridiniacean dinocysts with an isodeltaform to isothetaform 2a, an archeopyle that can result from the loss of the 2a only or all three intercalary plates and a more or less uniform covering of spines of coni on the cyst that may or may not reflect tabulation”. Vozzhennikovia tawanuiensis sp. nov. differs from Vozzhennikovia angulata Wilson, 1988 in lacking a periphragm that is sharply angular in outline, in not having densely arranged processes, and in lacking an easily discernible paracingulum. It differs from Vozzhennikovia rotunda (Wilson, 1967) Lentin and Williams, 1976 in lacking development of an apical and left antapical horn, in having a less globular shape, and in lacking spinules in the paracingulum area. Vozzhennikovia tawanuiensis sp. nov. is distinguished from Spinidinium densispinatum Stanley, 1965 by lacking a distinct paracingulum, by having no evidence of sutural spines and by lacking a well-developed left antapical horn and apical horn. Some specimens of Vozzhennikovia tawanuiensis sp. nov. resemble rounded forms of Apectodinium homomorphum (Deflandre and Cookson, 1955) Lentin and Williams, 1977; however, the short rod-like capitate processes are distinctive for V. tawanuiensis sp. nov. and, furthermore, A. homomorphum has a more uniform distribution of processes and evidence of intratabular ornamentation.