Back
Durotrigia vesiculata
Durotrigia vesiculala Bailey, 1990
Holotype: Bailey, 1990, pl.1, figs.1-2
Locus typicus: Fuller"s Earth, S England
Stratum typicum: Late Bajocian-?Late Bathonian
Original diagnosis: Bailey, 1990, p. 140
Subspherical to rounded pentagonal dinoflagellate cyst with or without a small apical horn and with a broadly rounded hypocyst. Autophragm thickened, with a complex microvesicular structure which appears spongy in transmitted light. Gonyaulacacean paratabulation (4", ?2a, 6", 6c, 6""", 1p, 1"""", 5s, fpa) indicated by low irregular parasutural ridges. Archeopyle variable, precingular, type 1P-5P.
Original description: Bailey, 1990, p. 141
Granular and vermicular elements of the ornament coalesce to form sutural ridges which reflect a gonyaulacacean paratabulation. The thick spongy wall structure may obscure details of paratabulation in transmitted light. Intratabular areas are sometimes reticulate on the outer surface of the autophragm, with coalescing elements forming a pattern of irregular rings, usually about 5 Ám in diameter (see Plate 3, figs. 1-3). Short linear features may also develop perpendicular to paraplate boundaries. Occasional specimens show extreme posterio-lateral thickening of the wall (Plate I , figs. 10-12), which is held to be within limitations of intra-specific variation. The archeopyle is formed by the loss of between one and five precingular paraplates (type 1P-5P). Cysts with vari- able dehiscence are recorded, though the 6" paraplate always remains attached with the anterior sulcal, forming a broad isthmus which connects the apical series to the hypocyst. Excystment begins dorsally at the 3" paraplate and progresses ventrally in both directions. The 6" paraplate is reduced in size, the width being roughly equal to that of the anterior sulcal plate at its widest point. The sulcal area is distinct, with five paraplates surrounding a smooth flagellarpore area (fpa), in which no detail can be distinguished.
Affinities:
Bailey, 1990, p. 141: Durotrigia vesiculata is unique within the genus in possessing an extremely thick and spongy autophragm. The 6" paraplate is reduced in size when compared to other species of the genus, though this feature may be difficult to see in transmitted light. Specimens with extreme posterio-lateral thickening of the autophragm, and in which only one opercular paraplate is developed, may resemble Aldorfia aldorfensis (Gocht 1970) Stover & Evitt 1978 (cf. Riding et al., 1985, pl. 4, fig.7). D. vesiculata can be distinguished from A. aldorfensis by the lack of an ectophragm and the variable precingular archeopyle on the former.
Holotype: Bailey, 1990, pl.1, figs.1-2
Locus typicus: Fuller"s Earth, S England
Stratum typicum: Late Bajocian-?Late Bathonian
Original diagnosis: Bailey, 1990, p. 140
Subspherical to rounded pentagonal dinoflagellate cyst with or without a small apical horn and with a broadly rounded hypocyst. Autophragm thickened, with a complex microvesicular structure which appears spongy in transmitted light. Gonyaulacacean paratabulation (4", ?2a, 6", 6c, 6""", 1p, 1"""", 5s, fpa) indicated by low irregular parasutural ridges. Archeopyle variable, precingular, type 1P-5P.
Original description: Bailey, 1990, p. 141
Granular and vermicular elements of the ornament coalesce to form sutural ridges which reflect a gonyaulacacean paratabulation. The thick spongy wall structure may obscure details of paratabulation in transmitted light. Intratabular areas are sometimes reticulate on the outer surface of the autophragm, with coalescing elements forming a pattern of irregular rings, usually about 5 Ám in diameter (see Plate 3, figs. 1-3). Short linear features may also develop perpendicular to paraplate boundaries. Occasional specimens show extreme posterio-lateral thickening of the wall (Plate I , figs. 10-12), which is held to be within limitations of intra-specific variation. The archeopyle is formed by the loss of between one and five precingular paraplates (type 1P-5P). Cysts with vari- able dehiscence are recorded, though the 6" paraplate always remains attached with the anterior sulcal, forming a broad isthmus which connects the apical series to the hypocyst. Excystment begins dorsally at the 3" paraplate and progresses ventrally in both directions. The 6" paraplate is reduced in size, the width being roughly equal to that of the anterior sulcal plate at its widest point. The sulcal area is distinct, with five paraplates surrounding a smooth flagellarpore area (fpa), in which no detail can be distinguished.
Affinities:
Bailey, 1990, p. 141: Durotrigia vesiculata is unique within the genus in possessing an extremely thick and spongy autophragm. The 6" paraplate is reduced in size when compared to other species of the genus, though this feature may be difficult to see in transmitted light. Specimens with extreme posterio-lateral thickening of the autophragm, and in which only one opercular paraplate is developed, may resemble Aldorfia aldorfensis (Gocht 1970) Stover & Evitt 1978 (cf. Riding et al., 1985, pl. 4, fig.7). D. vesiculata can be distinguished from A. aldorfensis by the lack of an ectophragm and the variable precingular archeopyle on the former.