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Amiculosphaera umbracula
Amiculosphaera umbracula, Harland, 1979
Holotype: Harland, 1979, pl. 2, fig. 1-3
Locus typicus: Bay of Biscay
Stratum typicum: Late Miocene-Pleistocene
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Original description: [Harland, 1979, p. 535]:
Diagnosis:
Cavate cyst with an epitractal pericoel supported apically by a single flaring apical process. Wall layers on the hypotract closely adpressed, except towards the cingulum where separation is initiated. Endoblast spherical to ovoid sometimes with a small apical boss. Periblast inflated, and ovoid, the epitract being larger and more expanded than the hypotract. Endophragm smooth, periphragm smooth to micropunctate.
Tabulation appears to be gonyaulacacean, ?4', 6'', 6c, ?''', 1'''',
the archeopyle is pre-cingular formed by the loss of 3'' in both wall layers.
Description (annotated):
Epitractal pericoel and 'cloak-like' periphragm is characteristic of this genus and the flared, almost from the process base, apical process is characteristic of the species. In addition to the apical process, there are four gonal protuberances at the antapical plate boundary which are made up of both wall layers (pl. 1, fig. 14, 22). The apical, precingular, and cingular plate series are particularly conspicuous, and on the margin of the periblast archeopyle the suture between paraplates 3c and 4c is often marked by a prominent peak (pl. 1, fig. 23; pl. 2, fig. 3).
The cingulum takes the form of a laevorotatory helicoid, is not indented, and may be displaced by up to its own width; the sulcus is devoid of plates but the arrangement of plates 1', 4' and the anterior margin of the ?anterior sulcal v-plate is often visible (pl. 2, fig. 2).
Archeopyle is usually conspicuous especially within the periblast where a large ?broad pentagonal plate 3'' has been lost (pl. 2, fig. 1,3). On the endoblast, however, the typical elongate pentagonal pre-cingular archeopyle shape is discernible. The endoblast operculum may sometimes be found within the cavity of the endoblast.
Dimensions:
Holotype, length of endoblast 56.0 µm, breadth 46.0 µm; length of periblast 80.0 µm, breadth 86 µm.
Range, length of endoblast 36.0-56.0 µm, breadth 44.0-70.0 µm; length of periblast 64.0-80.0 µm; breadth, 70.0-104.0 µm. 11 specimens measured.
Affinities:
Similarities and differences to the monospecific genus Erikania Morgenroth have already been noted. The distinct morphology of Amiculoshpaera umbracula sp. nov. distinguishes it from other described cysts.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Amiculosphaera µmbracula Harland, 1979b is a proximate circumcavate cyst with subcircular to rhomboidal outline in dorsal ventral view; the pericyst is basket-shaped, the hypopericyst hemispherical, epipericyst composed of transverse meridional band connected to endocyst by a funnel-like apical projection arising from the endocyst. Parasutural features are incompletely developed. In Lophocysta the periphragm is appressed to the endophragm dorsally and separated from it ventrally. Tabulation S-type.
Size: Pericyst length 64-80 µm, width 70-104 µm: endocyst length 36-56 µm, width 44-70 µm.
Holotype: Harland, 1979, pl. 2, fig. 1-3
Locus typicus: Bay of Biscay
Stratum typicum: Late Miocene-Pleistocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Harland, 1979, p. 535]:
Diagnosis:
Cavate cyst with an epitractal pericoel supported apically by a single flaring apical process. Wall layers on the hypotract closely adpressed, except towards the cingulum where separation is initiated. Endoblast spherical to ovoid sometimes with a small apical boss. Periblast inflated, and ovoid, the epitract being larger and more expanded than the hypotract. Endophragm smooth, periphragm smooth to micropunctate.
Tabulation appears to be gonyaulacacean, ?4', 6'', 6c, ?''', 1'''',
the archeopyle is pre-cingular formed by the loss of 3'' in both wall layers.
Description (annotated):
Epitractal pericoel and 'cloak-like' periphragm is characteristic of this genus and the flared, almost from the process base, apical process is characteristic of the species. In addition to the apical process, there are four gonal protuberances at the antapical plate boundary which are made up of both wall layers (pl. 1, fig. 14, 22). The apical, precingular, and cingular plate series are particularly conspicuous, and on the margin of the periblast archeopyle the suture between paraplates 3c and 4c is often marked by a prominent peak (pl. 1, fig. 23; pl. 2, fig. 3).
The cingulum takes the form of a laevorotatory helicoid, is not indented, and may be displaced by up to its own width; the sulcus is devoid of plates but the arrangement of plates 1', 4' and the anterior margin of the ?anterior sulcal v-plate is often visible (pl. 2, fig. 2).
Archeopyle is usually conspicuous especially within the periblast where a large ?broad pentagonal plate 3'' has been lost (pl. 2, fig. 1,3). On the endoblast, however, the typical elongate pentagonal pre-cingular archeopyle shape is discernible. The endoblast operculum may sometimes be found within the cavity of the endoblast.
Dimensions:
Holotype, length of endoblast 56.0 µm, breadth 46.0 µm; length of periblast 80.0 µm, breadth 86 µm.
Range, length of endoblast 36.0-56.0 µm, breadth 44.0-70.0 µm; length of periblast 64.0-80.0 µm; breadth, 70.0-104.0 µm. 11 specimens measured.
Affinities:
Similarities and differences to the monospecific genus Erikania Morgenroth have already been noted. The distinct morphology of Amiculoshpaera umbracula sp. nov. distinguishes it from other described cysts.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Amiculosphaera µmbracula Harland, 1979b is a proximate circumcavate cyst with subcircular to rhomboidal outline in dorsal ventral view; the pericyst is basket-shaped, the hypopericyst hemispherical, epipericyst composed of transverse meridional band connected to endocyst by a funnel-like apical projection arising from the endocyst. Parasutural features are incompletely developed. In Lophocysta the periphragm is appressed to the endophragm dorsally and separated from it ventrally. Tabulation S-type.
Size: Pericyst length 64-80 µm, width 70-104 µm: endocyst length 36-56 µm, width 44-70 µm.