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Leptodinium pustulatum
Leptodinium pustulatum Crouch et al., 2014, p.64–65, pl.1, figs.1–12.
Questionable assignment: Crouch et al. (2014, p.64).
Holotype: Crouch et al., 2014, pl.1, figs.1–3.
Age: middle Paleocene–earliest Eocene.
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Original description (Crouch et al., 2014):
Leptodinium? pustulatum Crouch et al., sp. nov. Plate I
Holotype: Sample U24/f1026 (Slide SM4836), England Finder coordinate H36/1; Plate I, 1–3.
Paratype: Sample U24/f1029 (Slide 1), England Finder co-ordinate M49/ 0; Plate I, 4–6.
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: With reference to the presence of pustules on the autophragm.
Previous illustrations: 2001, Acanthaulax? sp. A, Crouch, p. 43, Plate I, 1–2.
Description: A proximate cyst of small to intermediate size consisting of an autophragm. The surface of the autophragm has low ridges that form a parasutural ornamentation. The parasutural ridges are discernible by complete to incomplete single rows of almost connected low pustules. The ridges can be up to ~3 μm in height and the distal margins of the ridges are crenulate. Intratabular ornamentation consists of pustules or tubercles, which can sometimes be aligned or almost connected into secondary ridges. The cyst wall is smooth to finely granular where the surface is not ornamented. The paracingulum is generally discernible and the parasulcal region is visible, although identifying all individual paraplates is difficult. Ornamentation is sparse but present within the paracingulum and parasulcus. The cyst has an L-type ventral organisation, and appears to have neutral to very slight dextral torsion (position of the boundary between the postcingular 4‴/5‴ plates relative to the boundary between the precingular 3″/4″ plates). Apical and antapical horns or protrusions are absent. The archeopyle is a singleplate precingular, type P(3), and the operculum is free in most observed specimens. Paratabulation is expressed by parasutural ornamentation, but can be difficult to ascertain. Inferred paratabulation is: 3 to 4′, 5 to 6″, 6c, 1ps, ?s, 5 to 6‴, 1p, 1⁗.
Dimensions: Holotype - Range (number of specimens measured: 14)
Overall length: 56 µm - 49 (56) 66 µm
Overall width: 58 µm - 44 (52) 62 µm
Stratigraphic occurrence: Middle Paleocene (late Teurian)–earliest Eocene (early Waipawan). The LO of Leptodinium? pustulatum sp. nov. is in NZDP6 and calcareous nannofossil Zone NP5, based on observations at mid-Waipara River and ODP Site 1121. The LO is stratigraphically below the HO of Isabelidinium cingulatum. The HO of Leptodinium? pustulatum sp. nov. is very close to the Paleocene–Eocene boundary. Currently, the only observation is in Tawanui section where the HO is at 0.08 m (U24/f1081) above the P–E boundary (Crouch, 2001). Observed in mid-Waipara River, Tawanui, Toi-Flat-1 core, Angora Road, ODP Site 1121, and Moeraki–Hampden in North Otago (Crouch, 2001). Rare to common in sections examined.
Remarks: When first recorded, Leptodinium? pustulatum sp. nov. was tentatively placed in the genus Acanthaulax (Sarjeant, 1968) Brenner 1988, based on the character of the parasutural ridges, the presence of intratabular ornamentation and the lack of dextral torsion (Crouch, 2001). Poulsen (1996) considered Acanthaulax to be a taxonomic junior synonym of the genus Cribroperidinium (Neale and Sarjeant, 1962) Helenes, 1984. However, Leptodinium? pustulatum sp. nov. lacks distinctive Cribroperidinium characteristics such as marked dextral torsion, parallel accessory septa (‘growth bands’) and an apical protrusion. The species is tentatively included in the genus Leptodinium, based on the presence of an L-type ventral organisation, neutral torsion, and lack of apical protrusion; however, species of Leptodinium only possess parasutural septa and intratabular ornamentation is not present. Leptodinium? pustulatum sp. nov. is distinguished from the genus Corrudinium Stover and Evitt, 1978 by having an L-type ventral organisation, rather than a S-type organisation. Species of Corrudinium, however, do possess accessory ridges or septa. Leptodinium? pustulatum sp. nov. differs from species of Impagidinium Stover and Evitt, 1978 in possessing an L-type ventral organisation and accessory ridges. The cyst is generally seen in lateral view, rather than dorsal-ventral view.
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Questionable assignment: Crouch et al. (2014, p.64).
Holotype: Crouch et al., 2014, pl.1, figs.1–3.
Age: middle Paleocene–earliest Eocene.
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Original description (Crouch et al., 2014):
Leptodinium? pustulatum Crouch et al., sp. nov. Plate I
Holotype: Sample U24/f1026 (Slide SM4836), England Finder coordinate H36/1; Plate I, 1–3.
Paratype: Sample U24/f1029 (Slide 1), England Finder co-ordinate M49/ 0; Plate I, 4–6.
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: With reference to the presence of pustules on the autophragm.
Previous illustrations: 2001, Acanthaulax? sp. A, Crouch, p. 43, Plate I, 1–2.
Description: A proximate cyst of small to intermediate size consisting of an autophragm. The surface of the autophragm has low ridges that form a parasutural ornamentation. The parasutural ridges are discernible by complete to incomplete single rows of almost connected low pustules. The ridges can be up to ~3 μm in height and the distal margins of the ridges are crenulate. Intratabular ornamentation consists of pustules or tubercles, which can sometimes be aligned or almost connected into secondary ridges. The cyst wall is smooth to finely granular where the surface is not ornamented. The paracingulum is generally discernible and the parasulcal region is visible, although identifying all individual paraplates is difficult. Ornamentation is sparse but present within the paracingulum and parasulcus. The cyst has an L-type ventral organisation, and appears to have neutral to very slight dextral torsion (position of the boundary between the postcingular 4‴/5‴ plates relative to the boundary between the precingular 3″/4″ plates). Apical and antapical horns or protrusions are absent. The archeopyle is a singleplate precingular, type P(3), and the operculum is free in most observed specimens. Paratabulation is expressed by parasutural ornamentation, but can be difficult to ascertain. Inferred paratabulation is: 3 to 4′, 5 to 6″, 6c, 1ps, ?s, 5 to 6‴, 1p, 1⁗.
Dimensions: Holotype - Range (number of specimens measured: 14)
Overall length: 56 µm - 49 (56) 66 µm
Overall width: 58 µm - 44 (52) 62 µm
Stratigraphic occurrence: Middle Paleocene (late Teurian)–earliest Eocene (early Waipawan). The LO of Leptodinium? pustulatum sp. nov. is in NZDP6 and calcareous nannofossil Zone NP5, based on observations at mid-Waipara River and ODP Site 1121. The LO is stratigraphically below the HO of Isabelidinium cingulatum. The HO of Leptodinium? pustulatum sp. nov. is very close to the Paleocene–Eocene boundary. Currently, the only observation is in Tawanui section where the HO is at 0.08 m (U24/f1081) above the P–E boundary (Crouch, 2001). Observed in mid-Waipara River, Tawanui, Toi-Flat-1 core, Angora Road, ODP Site 1121, and Moeraki–Hampden in North Otago (Crouch, 2001). Rare to common in sections examined.
Remarks: When first recorded, Leptodinium? pustulatum sp. nov. was tentatively placed in the genus Acanthaulax (Sarjeant, 1968) Brenner 1988, based on the character of the parasutural ridges, the presence of intratabular ornamentation and the lack of dextral torsion (Crouch, 2001). Poulsen (1996) considered Acanthaulax to be a taxonomic junior synonym of the genus Cribroperidinium (Neale and Sarjeant, 1962) Helenes, 1984. However, Leptodinium? pustulatum sp. nov. lacks distinctive Cribroperidinium characteristics such as marked dextral torsion, parallel accessory septa (‘growth bands’) and an apical protrusion. The species is tentatively included in the genus Leptodinium, based on the presence of an L-type ventral organisation, neutral torsion, and lack of apical protrusion; however, species of Leptodinium only possess parasutural septa and intratabular ornamentation is not present. Leptodinium? pustulatum sp. nov. is distinguished from the genus Corrudinium Stover and Evitt, 1978 by having an L-type ventral organisation, rather than a S-type organisation. Species of Corrudinium, however, do possess accessory ridges or septa. Leptodinium? pustulatum sp. nov. differs from species of Impagidinium Stover and Evitt, 1978 in possessing an L-type ventral organisation and accessory ridges. The cyst is generally seen in lateral view, rather than dorsal-ventral view.
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