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Pareodinia nuda
Pareodinia nuda Downie, 1957, p.424, pl.20, fig.11; text-fig.2e ex Sarjeant, 1967b, p.254.
Originally Palaeoperidinium, subsequently Pareodinia.
Tax. jr. synonym of Pareodinia ceratophora Deflandre, 1947, according to Wiggins, 1975 and Stover and Evitt, 1978. Sarjeant, 1976 and Lentin and Williams, 1989 retained Pareodinia nuda as a separate species; however, Kunz, 1990 agreed with Wiggins, 1975.
The name Palaeoperidinium nudum Downie was not validly published in Downie (1957) since the generic name Palaeoperidinium was not validly published until 1967. Williams et al. (1998, p.467) accepted Sarjeant's (1967b) indirect reference to Downie (1957) as indication of a type (I.C.N. Article 40.3).
Holotype: Downie, 1957, p.20, fig.11
Locus typicus: Dorset, England
Stratum typicum: Late Kimmeridgian
Original diagnosis: Downie, 1957, p.424: Palaeoperidinium nudum
The test is ellipsoidal with a strong polar horn about one-, third of the total length. The tip of the horn is solid and faint striations occur at the base. A deep spiral groove is often present at the tip. A spiral equatorial furrow may be clearly or faintly seen in an entral position. No plates or longitudinal furrow are visible.
Dimensions of holotype: Length 105 µm; breadth 45 µm; length of horn 41 µm.
Affinities:
Downie, 1957, p. 424: Palaeoperidinium nudum
This common species was associated with Gonyaulax, longicornis. In general appearance the species are much alike, the important difference being the absence of armour in P. nudum. Some individuals belonging to G. Iongicornis would, on a casual examination, have been grouped with P. nudum. It is possible that P. nudum is a postecdysial form of G. Iongicornis, but a separate species has been created because intermediate forms are rare and the absence of armour is a striking feature.
Originally Palaeoperidinium, subsequently Pareodinia.
Tax. jr. synonym of Pareodinia ceratophora Deflandre, 1947, according to Wiggins, 1975 and Stover and Evitt, 1978. Sarjeant, 1976 and Lentin and Williams, 1989 retained Pareodinia nuda as a separate species; however, Kunz, 1990 agreed with Wiggins, 1975.
The name Palaeoperidinium nudum Downie was not validly published in Downie (1957) since the generic name Palaeoperidinium was not validly published until 1967. Williams et al. (1998, p.467) accepted Sarjeant's (1967b) indirect reference to Downie (1957) as indication of a type (I.C.N. Article 40.3).
Holotype: Downie, 1957, p.20, fig.11
Locus typicus: Dorset, England
Stratum typicum: Late Kimmeridgian
Original diagnosis: Downie, 1957, p.424: Palaeoperidinium nudum
The test is ellipsoidal with a strong polar horn about one-, third of the total length. The tip of the horn is solid and faint striations occur at the base. A deep spiral groove is often present at the tip. A spiral equatorial furrow may be clearly or faintly seen in an entral position. No plates or longitudinal furrow are visible.
Dimensions of holotype: Length 105 µm; breadth 45 µm; length of horn 41 µm.
Affinities:
Downie, 1957, p. 424: Palaeoperidinium nudum
This common species was associated with Gonyaulax, longicornis. In general appearance the species are much alike, the important difference being the absence of armour in P. nudum. Some individuals belonging to G. Iongicornis would, on a casual examination, have been grouped with P. nudum. It is possible that P. nudum is a postecdysial form of G. Iongicornis, but a separate species has been created because intermediate forms are rare and the absence of armour is a striking feature.