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Dinopterygium dimorphum
Dinopterygium dimorphum (Ioannides et al., 1977) emend. Drugg, 1978
Now Glossodinium. Originally (and now) Glossodinium, subsequently Dinopterygium.
Courtinat in Courtinat and Gaillard, 1980, retained this species in Glossodinium Ioannides et al., 1977. Courtinat, 1989, agreed with Drugg, 1978.
Poulsen, 1992, agreed with Courtinat in Courtinat and Gaillard, 1980.
Holotype: Ioannides et al., 1977, pl.2, figs13-14
Locus typicus: Clavel"s Hard, Dorset, England
Stratum typicum: Kimmeridgian
Translation Courtinat, 1989: LPP
Original description: Ioannides et al., 1977, p. 453: Glossodinium dimorphum
Diagnosis (that of the genus, Ioannides et al., 1977, p. 452): Cyst two-layered; in dorsal or ventral view subrhombohedral in outline; in apical or antapical view more or less circular. Epitract and hypotract of approximately equal size. Periphragm thin, finely folded, often in pseudoreticulate fashion. Periphragm ending in stout apical horn; distally, developing into complex prominence composed of a number of digitations of variable size. Cingulum well developed, bordered by membranous crests bearing radial striations (folds). In apical or antapical view, cingular crests appear invaginated toward sulcal zone, thereby indicating position of sulcus. Inner body large, normally closely appressed to periphragm except for apical and, rarely antapical regions. Tabulation not observed. Precingular archaeopyle occasionally occurs.
Description (annotated): Cyst two-layered; circular to slightly compressed dorsoventrally, more or less circular in apical or antapical orientation. Epitract terminates in a rounded to truncate stout horn, sometimes irregular in shape. Periphragm thin and transparent invariably folded giving rise to fine linear striations, in places or on entire surface, often assuming pseudoreticulate pattern. Periphragm distally developing into complex antapical structure composed of 2-6, but usually 3-4 digitations. In apical or antapical view, cingular crests encircle cyst except at sulcal region for about 12 Ám, where crests invaginate toward sulcal borders; in same view cingular crests show parallel-edged appearance. Inner body large, thin-walled, in close contact with periphragm, completely filling pericoel except in apical and rarely in antapical regions. Endophragm occasionally forming short apical protuberance but antapex, when observed, is rounded. Tabulation apperently absent but in rare cases some plates may be simulated by arrangements of folds. Precingular archaeopyle occasionally occurs, corresponding to position of plate 3"". Dimensions: Range: overall length 94-135 Ám, breadth 90-117 Ám; capsule length 69-97 Ám; cingular crests 8-17 Ám high; length of antapical prominence 17-30 Ám.
Emended description: Drugg, 1978, p. 67
Cyst biconical in shape with an epicystal archeopyle. The wall is thin and two-layered. The endophragm is smooth but the periphragm is ornamented. The epicyst is conical with the periphragm extending upward to form a short, broad, blunt apical horn. On some specimens the endophragm takes parts in the horn formation but in others it is rounded apically thus giving rise to a small apical
pericoel. The endophragm of the hypocyst is more or less bluntly rounded antapically but the periphragm extends downward to form 2 to 6 broadly flattened and pointed projections. The cross section of the cyst at the paracingulum is circular to slightly elliptical. A parasulcal depression or concavity is present and the paracingulum is absent here. The paracingulum is prominent and consists of ledges about 4 to 12 Ám in width. Both wall layers take part in the formation with a smooth endophragm and a radially folded or ridged periphragm. The ridges are usually spaced from 3 to 4 Ám apart and are quite prominent. The outer edges of the two layers do not always exactly coincide. The parasutural crests on the hypocyst are from 4 to 21 Ám high and may be either smooth or exhibit occasional radial folds or striae. The average height is about 12 Ám. The outer edges of the hypocyst parasutural crests are often lobate in the manner of a cockscomb. These crests become higher toward the antapex. The flanges bordering the parasulcus on the hypocyst are particularly high and prominent, The parasutural crests on the epicyst are less prominent and are often duplicate or double. They are about 2 to 5 Ám high. The periphragm of the paraplate areas between the parasutures is often ornamented with small circular tubercles about 1Ám in diameter. They consist of a raised circu]ar rim surrounding a small pit. They are usually spaced about 1 to 2,um apart. Strips adjacent to the parasutures are often, but not always, devoid of such ornamentation. Some specimens apparently lack the ornamentation of tubercles and instead are ornamented by low and crude ridges approaching a reticulate pattern. The epicystal archeopyle is formed by a separation through the paracingulum. As a result paracingular flanges are present on both epicyst and hypocyst. Paratabulation is present but is difficult to determine because of the ornamentation and the relatively thin walls of the cyst. It is probably 1 pr., 4", 6", Xc, 6""", 1p, 1"""", The paratabulation pattern is of the pyrodinioid type as opposed to gonyaulacid. The total cyst length ranges from 65 to 110 Ám with most being about 100 Ám.
Remark: Courtinat, 1989, p.219-220
Courtinat (in Courtinat and Gaillard), 1980, emended the genus Glossodinium to include the archaeopyle type then defined as (tA 3P). The transfer by Drugg (1978) had been rejected because the paratabulation of G. dimorphum did not correspond to that of Dinopterygium. That paratabulation does correspond to that of Dinopterygium; the paratabulation formula given in 1980 was incorrect. The
archaeopyle type is very variable. Some forms present a 3P(2""+3""+4"") or a 2P(2""+3"") type archaeopyle. In spite of the variability of the archaeopyle type, Drugg"s transfer is justified. Consequently, Glossodinium is a junioir synonym of Dinoptrerygium. Glossodinium reallocated a second species, G. bicuneatum, which was later transferred to Dinopterygium by Lentin and Williams (1982). This species does not belong in Dinopterygium. the holotype has been examined; is does not possess a visible archaeopyle, the cyst is not cavate and is composed of an autophragm only. The wall is not ornamented and the epicyst and hypocyst are conical. The paracingulum divides the cyst into two equal parts. The only genus corresponding to these characteristics is Cornudinium, although to Stover and Evitt (1978) it is not certain if Cornudinium is a cyst. Thus it is proposed to transfer D. bicuneatum to this genus and to use the name only for the type specimen.
Now Glossodinium. Originally (and now) Glossodinium, subsequently Dinopterygium.
Courtinat in Courtinat and Gaillard, 1980, retained this species in Glossodinium Ioannides et al., 1977. Courtinat, 1989, agreed with Drugg, 1978.
Poulsen, 1992, agreed with Courtinat in Courtinat and Gaillard, 1980.
Holotype: Ioannides et al., 1977, pl.2, figs13-14
Locus typicus: Clavel"s Hard, Dorset, England
Stratum typicum: Kimmeridgian
Translation Courtinat, 1989: LPP
Original description: Ioannides et al., 1977, p. 453: Glossodinium dimorphum
Diagnosis (that of the genus, Ioannides et al., 1977, p. 452): Cyst two-layered; in dorsal or ventral view subrhombohedral in outline; in apical or antapical view more or less circular. Epitract and hypotract of approximately equal size. Periphragm thin, finely folded, often in pseudoreticulate fashion. Periphragm ending in stout apical horn; distally, developing into complex prominence composed of a number of digitations of variable size. Cingulum well developed, bordered by membranous crests bearing radial striations (folds). In apical or antapical view, cingular crests appear invaginated toward sulcal zone, thereby indicating position of sulcus. Inner body large, normally closely appressed to periphragm except for apical and, rarely antapical regions. Tabulation not observed. Precingular archaeopyle occasionally occurs.
Description (annotated): Cyst two-layered; circular to slightly compressed dorsoventrally, more or less circular in apical or antapical orientation. Epitract terminates in a rounded to truncate stout horn, sometimes irregular in shape. Periphragm thin and transparent invariably folded giving rise to fine linear striations, in places or on entire surface, often assuming pseudoreticulate pattern. Periphragm distally developing into complex antapical structure composed of 2-6, but usually 3-4 digitations. In apical or antapical view, cingular crests encircle cyst except at sulcal region for about 12 Ám, where crests invaginate toward sulcal borders; in same view cingular crests show parallel-edged appearance. Inner body large, thin-walled, in close contact with periphragm, completely filling pericoel except in apical and rarely in antapical regions. Endophragm occasionally forming short apical protuberance but antapex, when observed, is rounded. Tabulation apperently absent but in rare cases some plates may be simulated by arrangements of folds. Precingular archaeopyle occasionally occurs, corresponding to position of plate 3"". Dimensions: Range: overall length 94-135 Ám, breadth 90-117 Ám; capsule length 69-97 Ám; cingular crests 8-17 Ám high; length of antapical prominence 17-30 Ám.
Emended description: Drugg, 1978, p. 67
Cyst biconical in shape with an epicystal archeopyle. The wall is thin and two-layered. The endophragm is smooth but the periphragm is ornamented. The epicyst is conical with the periphragm extending upward to form a short, broad, blunt apical horn. On some specimens the endophragm takes parts in the horn formation but in others it is rounded apically thus giving rise to a small apical
pericoel. The endophragm of the hypocyst is more or less bluntly rounded antapically but the periphragm extends downward to form 2 to 6 broadly flattened and pointed projections. The cross section of the cyst at the paracingulum is circular to slightly elliptical. A parasulcal depression or concavity is present and the paracingulum is absent here. The paracingulum is prominent and consists of ledges about 4 to 12 Ám in width. Both wall layers take part in the formation with a smooth endophragm and a radially folded or ridged periphragm. The ridges are usually spaced from 3 to 4 Ám apart and are quite prominent. The outer edges of the two layers do not always exactly coincide. The parasutural crests on the hypocyst are from 4 to 21 Ám high and may be either smooth or exhibit occasional radial folds or striae. The average height is about 12 Ám. The outer edges of the hypocyst parasutural crests are often lobate in the manner of a cockscomb. These crests become higher toward the antapex. The flanges bordering the parasulcus on the hypocyst are particularly high and prominent, The parasutural crests on the epicyst are less prominent and are often duplicate or double. They are about 2 to 5 Ám high. The periphragm of the paraplate areas between the parasutures is often ornamented with small circular tubercles about 1Ám in diameter. They consist of a raised circu]ar rim surrounding a small pit. They are usually spaced about 1 to 2,um apart. Strips adjacent to the parasutures are often, but not always, devoid of such ornamentation. Some specimens apparently lack the ornamentation of tubercles and instead are ornamented by low and crude ridges approaching a reticulate pattern. The epicystal archeopyle is formed by a separation through the paracingulum. As a result paracingular flanges are present on both epicyst and hypocyst. Paratabulation is present but is difficult to determine because of the ornamentation and the relatively thin walls of the cyst. It is probably 1 pr., 4", 6", Xc, 6""", 1p, 1"""", The paratabulation pattern is of the pyrodinioid type as opposed to gonyaulacid. The total cyst length ranges from 65 to 110 Ám with most being about 100 Ám.
Remark: Courtinat, 1989, p.219-220
Courtinat (in Courtinat and Gaillard), 1980, emended the genus Glossodinium to include the archaeopyle type then defined as (tA 3P). The transfer by Drugg (1978) had been rejected because the paratabulation of G. dimorphum did not correspond to that of Dinopterygium. That paratabulation does correspond to that of Dinopterygium; the paratabulation formula given in 1980 was incorrect. The
archaeopyle type is very variable. Some forms present a 3P(2""+3""+4"") or a 2P(2""+3"") type archaeopyle. In spite of the variability of the archaeopyle type, Drugg"s transfer is justified. Consequently, Glossodinium is a junioir synonym of Dinoptrerygium. Glossodinium reallocated a second species, G. bicuneatum, which was later transferred to Dinopterygium by Lentin and Williams (1982). This species does not belong in Dinopterygium. the holotype has been examined; is does not possess a visible archaeopyle, the cyst is not cavate and is composed of an autophragm only. The wall is not ornamented and the epicyst and hypocyst are conical. The paracingulum divides the cyst into two equal parts. The only genus corresponding to these characteristics is Cornudinium, although to Stover and Evitt (1978) it is not certain if Cornudinium is a cyst. Thus it is proposed to transfer D. bicuneatum to this genus and to use the name only for the type specimen.