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Renidinium gracile
Renidinium gracile Hultberg and Malmgren, 1985
Hultberg, 1985 gave the citation "Renidinium gracile sp.nov." and designated as the holotype the specimen illustrated in his pl.9, fig.G. This is the same specimen as the one illustrated by Hultberg and Malmgren, 1985, figs. 11H-I and likewise designated as the holotype of Renidinium gracile by those authors.
Holotype: Hultberg and Malmgren, 1985, figs.11H-I
Locus typicus: Limhamn, Sweden
Stratum typicum: Maastrichtian-Danian
Original description: Hultberg and Malmgren, 1985, p. 49-50
The endophragm is lenticular with two antapically located, rounded potrusions. These are asymmetrically developed, the right protrusion being stronger developed than the left. The endophragm is ovoidal. The periphragm has a rounded apical protrusion and two antapical pericoels, which reach their maximum extension between the cyst margin and the parasulcus, and are thus ventrally dominant. The pericoels extend antapically on the ventral side, forming two asymetrical antapical protrusions. Endophragm and periphragm are in close contact on the dorsal surface.
The endophragm is hyaline to very finely granulate. The periphragm is hyaline, except at paraplate boundaries on the dorsal surface, and in some very well preserved specimens perforate in the sulcal region and on the antapical protrusions. The archeopyle is apical, type tA, mostly with a free operculum. Sulcal notch is located left of midventral position. Primary archeopyle suture zig-zag, indicating six precingular paraplates. Further paratabulation is weakly expressed by folds in the periphragm at paraplate boundaries on the dorsal surface, enabling the recognition of paraplates 3""", 4""", 5""", and 1"""". Total paratabulation formula unknown, but is presumed to be typically gpnyaulacacean.
Dimensions: 65-75 µm.
Supplemental description: Hultberg, 1985, p. 143
Cavate cyst, composed of endophragm and periphragm, separated by ventroantapical and apical pericoels. The surface of the endophragm is smooth. The surface of the periphragm is slightly granulate. The shape of the endophragm is ellipsoidal to ovoidal, with an antapical indentation. The periphragm is ellipsoidal, with one short apical protrusion, and two ventroantapical protrusions. Paratabulation is indicated by the archeopyle margin and denser granulation at the parasutures on the dorsal side of the periphragm. The archeopyle margin enables the recognition of paraplates 1" to 6". Granulation at parasutures enables the recognition of paraplates 3""",4""",5""", and 1"""". Total paratabulation formula unknown, but the paratabulation presumably follows the standard gonyaulacacean paratabulation formula. The archeopyle is apical, type tA. Operculum free.
Paracingulum is indicated by denser granulation at the paracingular margins.
Parasulcus generally not indicated. Size - 91-103 µm (length), 63-75 µm (breadth).
Affinities:
Hultberg and Malmgren, 1985, p. 50: Renidinium gracilis is distinguished from R. membraniferum Morgenroth (1968) by its thinner cyst walls and its more faint paratabulation, which is expressed rather by thin folds in the periphragm at paraplate boundaries than of strongly protruding subcircular folds in the periphragm that are present in Morgenroth"s specimen. It may be distinguished from R. vitilare by its total lack of ornamentation.
Hultberg, 1985, p. 143: Renidinium gracilis is distinguishable from other species of Renidinium by its paratabulation, expressed by denser granulation at paraplate boundaries.
Hultberg, 1985 gave the citation "Renidinium gracile sp.nov." and designated as the holotype the specimen illustrated in his pl.9, fig.G. This is the same specimen as the one illustrated by Hultberg and Malmgren, 1985, figs. 11H-I and likewise designated as the holotype of Renidinium gracile by those authors.
Holotype: Hultberg and Malmgren, 1985, figs.11H-I
Locus typicus: Limhamn, Sweden
Stratum typicum: Maastrichtian-Danian
Original description: Hultberg and Malmgren, 1985, p. 49-50
The endophragm is lenticular with two antapically located, rounded potrusions. These are asymmetrically developed, the right protrusion being stronger developed than the left. The endophragm is ovoidal. The periphragm has a rounded apical protrusion and two antapical pericoels, which reach their maximum extension between the cyst margin and the parasulcus, and are thus ventrally dominant. The pericoels extend antapically on the ventral side, forming two asymetrical antapical protrusions. Endophragm and periphragm are in close contact on the dorsal surface.
The endophragm is hyaline to very finely granulate. The periphragm is hyaline, except at paraplate boundaries on the dorsal surface, and in some very well preserved specimens perforate in the sulcal region and on the antapical protrusions. The archeopyle is apical, type tA, mostly with a free operculum. Sulcal notch is located left of midventral position. Primary archeopyle suture zig-zag, indicating six precingular paraplates. Further paratabulation is weakly expressed by folds in the periphragm at paraplate boundaries on the dorsal surface, enabling the recognition of paraplates 3""", 4""", 5""", and 1"""". Total paratabulation formula unknown, but is presumed to be typically gpnyaulacacean.
Dimensions: 65-75 µm.
Supplemental description: Hultberg, 1985, p. 143
Cavate cyst, composed of endophragm and periphragm, separated by ventroantapical and apical pericoels. The surface of the endophragm is smooth. The surface of the periphragm is slightly granulate. The shape of the endophragm is ellipsoidal to ovoidal, with an antapical indentation. The periphragm is ellipsoidal, with one short apical protrusion, and two ventroantapical protrusions. Paratabulation is indicated by the archeopyle margin and denser granulation at the parasutures on the dorsal side of the periphragm. The archeopyle margin enables the recognition of paraplates 1" to 6". Granulation at parasutures enables the recognition of paraplates 3""",4""",5""", and 1"""". Total paratabulation formula unknown, but the paratabulation presumably follows the standard gonyaulacacean paratabulation formula. The archeopyle is apical, type tA. Operculum free.
Paracingulum is indicated by denser granulation at the paracingular margins.
Parasulcus generally not indicated. Size - 91-103 µm (length), 63-75 µm (breadth).
Affinities:
Hultberg and Malmgren, 1985, p. 50: Renidinium gracilis is distinguished from R. membraniferum Morgenroth (1968) by its thinner cyst walls and its more faint paratabulation, which is expressed rather by thin folds in the periphragm at paraplate boundaries than of strongly protruding subcircular folds in the periphragm that are present in Morgenroth"s specimen. It may be distinguished from R. vitilare by its total lack of ornamentation.
Hultberg, 1985, p. 143: Renidinium gracilis is distinguishable from other species of Renidinium by its paratabulation, expressed by denser granulation at paraplate boundaries.