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Endoscrinium luridum
From Fensome et al., 2019:
Endoscrinium luridum (Deflandre, 1939a, p.166, pl.5, figs.4–6) Gocht, 1970b, p.144–146. Holotype: Deflandre, 1939a, pl.5,
figs.4–5; Jan du Chêne et al., 1986a, pl.109, figs.6–8. Originally Gymnodinium (Appendix B), subsequently
Scriniodinium, thirdly (and now) Endoscrinium, fourthly Tubotuberella. Lentin and Williams (1993, p.209) retained
this species in Endoscrinium. Taxonomic junior synonym: Endoscrinium asymmetricum, according to Courtinat
(2006, p.212). Age: early Oxfordian.
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Original description (Deflandre, 1939a) (translated from French):
Gymnodinium luridum n. sp.
Plate V, figs. 4 to 6.
Holotype: AM 44. Paratypes: AM 45, AM 59, AM 60.
The various specimens encountered so far appear encysted, like G. crystallinum, and are also generally quite flattened. The cyst is rounded, irregularly spheroidal, sometimes projecting slightly toward the apex, but this may be merely an accidental feature.
The outer membrane, very thin and fragile, forms a transverse groove that is very easily recognizable in places, but never distinct along its entire length. I have not seen a longitudinal groove. The part considered inferior roughly follows the shape of the cyst, but more irregularly; it is sometimes jagged or (secondarily) pleated. It is above all the epitheca that characterizes this organism, which is quite difficult to analyze due to the difficulty in separating aspects due to fossilization (folds, breaks) from those that appear to be original. The figures clearly show that the membrane, towards the apex, forms a sort of flattened truncated cone, whose sides widen and merge with the membrane, often reaching the transverse groove. In contrast to these kinds of folds, the membrane, at mid-height or higher, forms a sort of half-collar with both sides protruding. It is therefore easy to imagine that the organism is clearly asymmetrical, and this aspect is found very precisely on half a dozen specimens, which proves that it is not due to secondary folding. On the other hand, the indications giving the appearance of "plates" on certain figures are perhaps due either to breaks or to folds.
The cyst membrane, although thin, is always thicker than that of the cell itself. Both are, in their natural state, slightly brownish in color. I was able to stain them very well with aurantia, safranin, ruthenium red, and fuchsin. Carmine alum and Sudan III had no effect (on one specimen!).
The dimensions are as follows: cyst, 50/60 μ; cell. Holotype: length, 69 μ; width, 68 μ. Paratypes: lengths, 62, 67, 80 μ; widths, 70, 72, 87 μ.
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Remark: Courtinat, 1989, p.216
The transfer by Davies (1983) is not adopted. The outline of the Tubotuberella forms is not the same as that of the Endoscrinium forms. The antapical paraplate in Tubotuberella possesses an opisthopyle in posterior position, whilst in Endoscrinium it is in anterior position. E. luridum has an opisthopyle in anterior position. The other characteristics of E. luridum are a type P/C apical, a type 1u/1i ventral, and a type gamma paratabulation, and a symmetrical antapical paraplate.
The crests are spinous; this morphological characteristic has been observed on the holotype.
Supplemental description: Pocock, 1972, p.91
Theca comprises an irregularly spheroidal capsule enclosed in a thin outer wall; dorsoventrally flattened; outer wall carries a fairly prominent transverse furrow; longitudinal furrow and plating obscure; tabulation indeterminate; hypothecal extension of outer wall asymmetric; extending about 6.0 µm apically of the capsule; epithecal extensions double and of different sizes, extending about 3.0 µm and 5.0 µm apically of the capsule; archeopyle precingular; capsule about 1.0 µm thick; smooth to scabrate; outer wall less than 0.5 µm thick; smooth and transparent; color of capsule amber; length of theca 63.0 (72.3) 80.0 µµm; width of theca 55.0 (66.3) 74.0 µm; length of capsule 48.0 (57.0) 63.0 µm; width of capsule 40.0 (58.0) 62.0 µm.
Affinities:
Pocock, 1972, p.91: This species appears to correspond closely with Deflandre's original description and figures of G. Iuridum, and with Sarjeant's photographs of specimens assigned to the same species. The grains assigned to S. Iuridum by Klement (1960, pp.21-22, pl.1, figs.2--3) may represent a distinct species.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Endoscrinium luridum (Deflandre, 1938a) Gocht, 1970b, is similar to E.asymmetricum in having a winglike ventral area of the hypocyst, which projects over the antapical paraplate, which is ventral in position. However, in E.asymmetricum the lobes of the winglike hypocystal feature are markedly different in size, this disparity gives the distinctive asymmetrical dorso-ventral outline. E.asymmetricum is also more angular in outline and more elongate longitudinally than E.luridum. The only opening in the periphragm of E.luridum is the archeopyle. E.asymmetricum may also have one or two opisthopyles. Size: length of 107 µm, minimum of 49 µm. The holotype is 68 x 69 µm.
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Endoscrinium luridum (Deflandre, 1939a, p.166, pl.5, figs.4–6) Gocht, 1970b, p.144–146. Holotype: Deflandre, 1939a, pl.5,
figs.4–5; Jan du Chêne et al., 1986a, pl.109, figs.6–8. Originally Gymnodinium (Appendix B), subsequently
Scriniodinium, thirdly (and now) Endoscrinium, fourthly Tubotuberella. Lentin and Williams (1993, p.209) retained
this species in Endoscrinium. Taxonomic junior synonym: Endoscrinium asymmetricum, according to Courtinat
(2006, p.212). Age: early Oxfordian.
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Original description (Deflandre, 1939a) (translated from French):
Gymnodinium luridum n. sp.
Plate V, figs. 4 to 6.
Holotype: AM 44. Paratypes: AM 45, AM 59, AM 60.
The various specimens encountered so far appear encysted, like G. crystallinum, and are also generally quite flattened. The cyst is rounded, irregularly spheroidal, sometimes projecting slightly toward the apex, but this may be merely an accidental feature.
The outer membrane, very thin and fragile, forms a transverse groove that is very easily recognizable in places, but never distinct along its entire length. I have not seen a longitudinal groove. The part considered inferior roughly follows the shape of the cyst, but more irregularly; it is sometimes jagged or (secondarily) pleated. It is above all the epitheca that characterizes this organism, which is quite difficult to analyze due to the difficulty in separating aspects due to fossilization (folds, breaks) from those that appear to be original. The figures clearly show that the membrane, towards the apex, forms a sort of flattened truncated cone, whose sides widen and merge with the membrane, often reaching the transverse groove. In contrast to these kinds of folds, the membrane, at mid-height or higher, forms a sort of half-collar with both sides protruding. It is therefore easy to imagine that the organism is clearly asymmetrical, and this aspect is found very precisely on half a dozen specimens, which proves that it is not due to secondary folding. On the other hand, the indications giving the appearance of "plates" on certain figures are perhaps due either to breaks or to folds.
The cyst membrane, although thin, is always thicker than that of the cell itself. Both are, in their natural state, slightly brownish in color. I was able to stain them very well with aurantia, safranin, ruthenium red, and fuchsin. Carmine alum and Sudan III had no effect (on one specimen!).
The dimensions are as follows: cyst, 50/60 μ; cell. Holotype: length, 69 μ; width, 68 μ. Paratypes: lengths, 62, 67, 80 μ; widths, 70, 72, 87 μ.
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Remark: Courtinat, 1989, p.216
The transfer by Davies (1983) is not adopted. The outline of the Tubotuberella forms is not the same as that of the Endoscrinium forms. The antapical paraplate in Tubotuberella possesses an opisthopyle in posterior position, whilst in Endoscrinium it is in anterior position. E. luridum has an opisthopyle in anterior position. The other characteristics of E. luridum are a type P/C apical, a type 1u/1i ventral, and a type gamma paratabulation, and a symmetrical antapical paraplate.
The crests are spinous; this morphological characteristic has been observed on the holotype.
Supplemental description: Pocock, 1972, p.91
Theca comprises an irregularly spheroidal capsule enclosed in a thin outer wall; dorsoventrally flattened; outer wall carries a fairly prominent transverse furrow; longitudinal furrow and plating obscure; tabulation indeterminate; hypothecal extension of outer wall asymmetric; extending about 6.0 µm apically of the capsule; epithecal extensions double and of different sizes, extending about 3.0 µm and 5.0 µm apically of the capsule; archeopyle precingular; capsule about 1.0 µm thick; smooth to scabrate; outer wall less than 0.5 µm thick; smooth and transparent; color of capsule amber; length of theca 63.0 (72.3) 80.0 µµm; width of theca 55.0 (66.3) 74.0 µm; length of capsule 48.0 (57.0) 63.0 µm; width of capsule 40.0 (58.0) 62.0 µm.
Affinities:
Pocock, 1972, p.91: This species appears to correspond closely with Deflandre's original description and figures of G. Iuridum, and with Sarjeant's photographs of specimens assigned to the same species. The grains assigned to S. Iuridum by Klement (1960, pp.21-22, pl.1, figs.2--3) may represent a distinct species.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Endoscrinium luridum (Deflandre, 1938a) Gocht, 1970b, is similar to E.asymmetricum in having a winglike ventral area of the hypocyst, which projects over the antapical paraplate, which is ventral in position. However, in E.asymmetricum the lobes of the winglike hypocystal feature are markedly different in size, this disparity gives the distinctive asymmetrical dorso-ventral outline. E.asymmetricum is also more angular in outline and more elongate longitudinally than E.luridum. The only opening in the periphragm of E.luridum is the archeopyle. E.asymmetricum may also have one or two opisthopyles. Size: length of 107 µm, minimum of 49 µm. The holotype is 68 x 69 µm.
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