Back
Ovoidinium incorporeum
Ovoidinium incorporeum Duxbury 1983
Originally (and now) Ovoidinium, subsequently Ascodinium.
Lentin and Williams, 1985, transferred this species to Ascodinium Cookson and Eisenack, 1960. Lentin and Williams, 1989, retained it in Ovoidinium.
Holotype: Duxbury, 1983, pl.10, fig.14, text-fig.31
Locus typicus: Redcliff section, Isle of Wight, England
Stratum typicum: Late Aptian-Early Albian
Original diagnosis: Duxbury, 1983, p. 65
A thin-walled, dorso-ventrally flattened species of Ovoidinium. Both endo- and periphragm may be extensively folded and the endophragm surface may be smooth or finely granular. Anterior and posterior cavation is developed with the latter considerably better developed than the former. A tA tI archeopyle is developed with the operculum only rarely remaining attached. Low ridges or periphragm folds may indicate the paracingulum and some parasutures.
Observed Dimensions: Holotype - 67 x 52 Ám. Complete specimens - 67 (64) 55 x 52 (46) 41 Ám. Operculum detached - 52 (49) 44 x 58 (49) 38 Ám.
Affinities:
Duxbury, 1983, p. 65: The posterior cavation in O. incorporeum is approximately rounded triangular in outline with the apex of the triangle towards the antapex of the cyst. It does, however, possess a right lateral bulge and it may be suggested, therefore, that a left antapical and reduced right-antapical horns are being reflected in the posterior cavation of this species. O. incorporeum is most comparable with Ovoidinium incomptum Duxbury and Ovoidinium scabrosum (Cepadinium variabilis Cookson and Hughes, 1964). It differs from the former by being bicavate with well-developed anterior and posterior cavations (the latter is always better developed than the former). O. scabrosum is a thicker-walled, more robust species than O. incorporeum and its posterior cavation appears to reflect two equally well-developed antapical horns (see Cookson and Hughes, 1964, pl. 5, figs. 1-3) as opposed to the considerably better developed left-antapical of O. incorporeum.
Originally (and now) Ovoidinium, subsequently Ascodinium.
Lentin and Williams, 1985, transferred this species to Ascodinium Cookson and Eisenack, 1960. Lentin and Williams, 1989, retained it in Ovoidinium.
Holotype: Duxbury, 1983, pl.10, fig.14, text-fig.31
Locus typicus: Redcliff section, Isle of Wight, England
Stratum typicum: Late Aptian-Early Albian
Original diagnosis: Duxbury, 1983, p. 65
A thin-walled, dorso-ventrally flattened species of Ovoidinium. Both endo- and periphragm may be extensively folded and the endophragm surface may be smooth or finely granular. Anterior and posterior cavation is developed with the latter considerably better developed than the former. A tA tI archeopyle is developed with the operculum only rarely remaining attached. Low ridges or periphragm folds may indicate the paracingulum and some parasutures.
Observed Dimensions: Holotype - 67 x 52 Ám. Complete specimens - 67 (64) 55 x 52 (46) 41 Ám. Operculum detached - 52 (49) 44 x 58 (49) 38 Ám.
Affinities:
Duxbury, 1983, p. 65: The posterior cavation in O. incorporeum is approximately rounded triangular in outline with the apex of the triangle towards the antapex of the cyst. It does, however, possess a right lateral bulge and it may be suggested, therefore, that a left antapical and reduced right-antapical horns are being reflected in the posterior cavation of this species. O. incorporeum is most comparable with Ovoidinium incomptum Duxbury and Ovoidinium scabrosum (Cepadinium variabilis Cookson and Hughes, 1964). It differs from the former by being bicavate with well-developed anterior and posterior cavations (the latter is always better developed than the former). O. scabrosum is a thicker-walled, more robust species than O. incorporeum and its posterior cavation appears to reflect two equally well-developed antapical horns (see Cookson and Hughes, 1964, pl. 5, figs. 1-3) as opposed to the considerably better developed left-antapical of O. incorporeum.