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Leptodinium pilum
Leptodinium? pilum (Gocht, 1959, p.56–57, pl.6, fig.14; pl.8, fig.8 ex Sarjeant, 1967b, p.254) Sarjeant, 1969, p.13.
Originally Palaeoperidinium, subsequently Gonyaulacysta, thirdly (and now) Leptodinium?.
At the time of the transfer, Sarjeant, 1969, questionably included this species in Leptodinium.
Stover and Evitt, 1978, considered this to be a problematical species of Leptodinium, as did Jan du Chêne et al., 1986, who also recommended that the name be restricted to the holotype.
The name Palaeoperidinium pilum was not validly published in Gocht (1959) since the generic name Palaeoperidinium was not validly published until 1967. Williams et al. (1998, p.372) accepted Sarjeant's (1967b) indirect reference to Gocht (1959) as indication of a type (I.C.N. Article 40.3). Jan du Chêne et al. (1986a, p.211) recommended that this name be restricted to the holotype.
Holotype: Gocht, 1959, pl.6, fig.14; Jan du Chêne et al., 1986, pl.73, figs.7-8
Age: Valanginian
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Original description: [Gocht, 1959] (translated from German):
Type: The specimen shown and preserved in preparation No. 88.
Locus typicus: Rühlertwist 3 borehole (Emsland).
Stratum typicalum: Obervalendis 2 (middle dichotomous layers).
Diagnosis: Carapace elongated, pentagonal. Epitheca almost straight-edged, tapered; hypotheca somewhat asymmetrical, angled obliquely at the antapex. Not a true girdle; the sulcus is rather indicated by an equatorial ridge, reinforced by a dermal rim but not entirely surrounding the carapace. The lateral margin is bordered by dermal ridges, as is a rounded-triangular antapecal field. Another marginal ridge runs medially on the "back" of the carapace from the apex almost to the antapecal field. Membrane not very strong, finely granulated. Notes: The only specimen of the species is the largest dinoflagellate in my material. Its shape differs so markedly from all known forms that it should be considered a separate species. The main criteria are size and outline, since not all armor elements could be identified due to compression. Despite the clearly defined antapic "plate," in my opinion, this cannot be described as a true tabulation. Rather, the edges delimit approximately six simple fields, which, with the exception of the antapic field, are quite large. The absence of a belt also suggests a "closed" armor, not composed of plates. Until the detailed relationships are clarified, it seems appropriate to assign the species to the collective genus Palaeoperidinium, even though no paneling is present. A second specimen with a broad, spindle-shaped outline is somewhat similar to our species, but unfortunately, it has been heavily folded. Here, too, there are lateral marginal edges and a longitudinal edge running between the pointed poles, as well as a transverse ridge. One pole field is missing. The "epitheca" has an opening. Dimensions: Typical length 195 µ, greatest width (at the level of the crossbar) 93 µ. The spindle-shaped piece measures 97 x 78 µ. Material: 1 specimen from sample 4.
Originally Palaeoperidinium, subsequently Gonyaulacysta, thirdly (and now) Leptodinium?.
At the time of the transfer, Sarjeant, 1969, questionably included this species in Leptodinium.
Stover and Evitt, 1978, considered this to be a problematical species of Leptodinium, as did Jan du Chêne et al., 1986, who also recommended that the name be restricted to the holotype.
The name Palaeoperidinium pilum was not validly published in Gocht (1959) since the generic name Palaeoperidinium was not validly published until 1967. Williams et al. (1998, p.372) accepted Sarjeant's (1967b) indirect reference to Gocht (1959) as indication of a type (I.C.N. Article 40.3). Jan du Chêne et al. (1986a, p.211) recommended that this name be restricted to the holotype.
Holotype: Gocht, 1959, pl.6, fig.14; Jan du Chêne et al., 1986, pl.73, figs.7-8
Age: Valanginian
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Original description: [Gocht, 1959] (translated from German):
Type: The specimen shown and preserved in preparation No. 88.
Locus typicus: Rühlertwist 3 borehole (Emsland).
Stratum typicalum: Obervalendis 2 (middle dichotomous layers).
Diagnosis: Carapace elongated, pentagonal. Epitheca almost straight-edged, tapered; hypotheca somewhat asymmetrical, angled obliquely at the antapex. Not a true girdle; the sulcus is rather indicated by an equatorial ridge, reinforced by a dermal rim but not entirely surrounding the carapace. The lateral margin is bordered by dermal ridges, as is a rounded-triangular antapecal field. Another marginal ridge runs medially on the "back" of the carapace from the apex almost to the antapecal field. Membrane not very strong, finely granulated. Notes: The only specimen of the species is the largest dinoflagellate in my material. Its shape differs so markedly from all known forms that it should be considered a separate species. The main criteria are size and outline, since not all armor elements could be identified due to compression. Despite the clearly defined antapic "plate," in my opinion, this cannot be described as a true tabulation. Rather, the edges delimit approximately six simple fields, which, with the exception of the antapic field, are quite large. The absence of a belt also suggests a "closed" armor, not composed of plates. Until the detailed relationships are clarified, it seems appropriate to assign the species to the collective genus Palaeoperidinium, even though no paneling is present. A second specimen with a broad, spindle-shaped outline is somewhat similar to our species, but unfortunately, it has been heavily folded. Here, too, there are lateral marginal edges and a longitudinal edge running between the pointed poles, as well as a transverse ridge. One pole field is missing. The "epitheca" has an opening. Dimensions: Typical length 195 µ, greatest width (at the level of the crossbar) 93 µ. The spindle-shaped piece measures 97 x 78 µ. Material: 1 specimen from sample 4.