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Pyxidinopsis nuda
From Fensome et al., 2019:
Pyxidinopsis ?nuda (Nagy, 1969, p.291, pl.1, fig.1) Williams et al., 1998, p.520–521. Holotype: Nagy, 1969, pl.1, fig.1. Originally Palaeoperidinium nudum Nagy, subsequently Palaeoperidinium pannonium (name illegitimate), thirdly Phthanoperidinium pannonium (name illegitimate), fourthly Gonyaulacysta? nuda, fifthly Tectatodinium? nudum, sixthly Tectatodinium pannonium (name illegitimate), seventhly Pyxidinopsis? pannonia (name illegitimate), eighthly (and now) Pyxidinopsis? nuda. Questionable assignment: Head (1994a, p.308), for Pyxidinopsis? pannonia. Nomenclatural junior synonym: Palaeoperidinium (subsequently Phthanoperidinium, Tectatodinium? and Pyxidinopsis?) pannonium, which has the same type. Lentin and Williams (1973, p.106) proposed the name Palaeoperidinium pannonium for Palaeoperidinium nudum Nagy in the belief that the latter was an illegitimate junior homonym of Palaeoperidinium nudum Downie. However, Williams et al. (1998, p.521) re-interpreted Palaeoperidinium nudum Downie to be an invalid name; thus, Palaeoperidinium nudum Nagy must be considered as a validly published and legitimate name. In light of this, Williams et al. (1998, p.520–521) proposed the combination Pyxidinopsis? nuda. Age: Late Miocene.
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Original description [Nagy, 1969]:
Palaeoperidinium nudum n. sp.
Plate I, Fig. 1
Holotype: Borehole H. 53, sample No 4, slide No 1, 33,7 X 169,1.
Locus typicus: Hidas.
Stratum typicum: Upper Pannonian, silty clay-marl, borehole H. 53, depth 132.5 to 134.8 m.
Diagnosis: A spheroidal theca of 65 by 54 μ size. The transverse band is about 5 μ wide, slightly helicoidal. There are a few meridional ridges, presumably vestiges of a tabulation. The apex bears a crack indicative of a large pylome. In the side view, the fossil is finely baculate. The bacula, 1 to 1.5 μ long, lend the test a reticulate relief. The surface bears spines about 2 μ big, spaced 10 to 12 μ apart. There are a few verruca-like prominences, some of which form the rudiments of one peak at the apex, two at the antapex. In the zone corresponding to the helicoidal ring there are two small verruca-like prominences.
Differential diagnosis: The fossil resembles Deflandre’s Palaeoperidinium nuciforme (1938, Pl. VIII, Figs. 5, 6). However, P. nuciforme is covered with spines that are longer than the bacula of the new species. The transversal ring of P. nuciforme is more pronounced, and the prominence at the apex is longer.
Remarks: Our material from the Pannonian of the Mecsek Mountains has yielded just a few specimens. Placing them into the genus established by Deflandre in 1934 is justified on the grounds that the thecae bear morphological features indicative of Peridinium, and that tabulation can at most be surmised on our fossils. As the sediment that has yielded these fossils is relatively recent and contains peridinia of better preservation, too, W. Wetzel’s attribution of the lack of tabulation to the digestive processes of plankton-eating organisms (1952, p. 407) seems plausible. However, lack of tabulation may be due to inorganic corrosion, too.
Pyxidinopsis ?nuda (Nagy, 1969, p.291, pl.1, fig.1) Williams et al., 1998, p.520–521. Holotype: Nagy, 1969, pl.1, fig.1. Originally Palaeoperidinium nudum Nagy, subsequently Palaeoperidinium pannonium (name illegitimate), thirdly Phthanoperidinium pannonium (name illegitimate), fourthly Gonyaulacysta? nuda, fifthly Tectatodinium? nudum, sixthly Tectatodinium pannonium (name illegitimate), seventhly Pyxidinopsis? pannonia (name illegitimate), eighthly (and now) Pyxidinopsis? nuda. Questionable assignment: Head (1994a, p.308), for Pyxidinopsis? pannonia. Nomenclatural junior synonym: Palaeoperidinium (subsequently Phthanoperidinium, Tectatodinium? and Pyxidinopsis?) pannonium, which has the same type. Lentin and Williams (1973, p.106) proposed the name Palaeoperidinium pannonium for Palaeoperidinium nudum Nagy in the belief that the latter was an illegitimate junior homonym of Palaeoperidinium nudum Downie. However, Williams et al. (1998, p.521) re-interpreted Palaeoperidinium nudum Downie to be an invalid name; thus, Palaeoperidinium nudum Nagy must be considered as a validly published and legitimate name. In light of this, Williams et al. (1998, p.520–521) proposed the combination Pyxidinopsis? nuda. Age: Late Miocene.
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Original description [Nagy, 1969]:
Palaeoperidinium nudum n. sp.
Plate I, Fig. 1
Holotype: Borehole H. 53, sample No 4, slide No 1, 33,7 X 169,1.
Locus typicus: Hidas.
Stratum typicum: Upper Pannonian, silty clay-marl, borehole H. 53, depth 132.5 to 134.8 m.
Diagnosis: A spheroidal theca of 65 by 54 μ size. The transverse band is about 5 μ wide, slightly helicoidal. There are a few meridional ridges, presumably vestiges of a tabulation. The apex bears a crack indicative of a large pylome. In the side view, the fossil is finely baculate. The bacula, 1 to 1.5 μ long, lend the test a reticulate relief. The surface bears spines about 2 μ big, spaced 10 to 12 μ apart. There are a few verruca-like prominences, some of which form the rudiments of one peak at the apex, two at the antapex. In the zone corresponding to the helicoidal ring there are two small verruca-like prominences.
Differential diagnosis: The fossil resembles Deflandre’s Palaeoperidinium nuciforme (1938, Pl. VIII, Figs. 5, 6). However, P. nuciforme is covered with spines that are longer than the bacula of the new species. The transversal ring of P. nuciforme is more pronounced, and the prominence at the apex is longer.
Remarks: Our material from the Pannonian of the Mecsek Mountains has yielded just a few specimens. Placing them into the genus established by Deflandre in 1934 is justified on the grounds that the thecae bear morphological features indicative of Peridinium, and that tabulation can at most be surmised on our fossils. As the sediment that has yielded these fossils is relatively recent and contains peridinia of better preservation, too, W. Wetzel’s attribution of the lack of tabulation to the digestive processes of plankton-eating organisms (1952, p. 407) seems plausible. However, lack of tabulation may be due to inorganic corrosion, too.