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Herendeenia postprojecta
Herendeenia postprojecta Stover and Helby, 1987
Holotype: Stover and Helby, 1987, fig.11A-E
Locus typicus: Exmouth Plateau, W Australia
Stratum typicum: Hauterivian-Aptian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Herendeenia postprojecta Stover and Helby, 1987c, differs from H. pisciformis in having a single intratabular process on the antapical paraplate, which lies on the ventral surface, a pitted ornamentation rather than one consisting of projections, and a longer and narrower apical horn. H. alaskaensis, which is similar to the elongate ellipsoidal forms of H. postprojecta, differs in lacking the intratabular process, and in having a thinner cyst wall which is granulate rather than pitted. Size overall length 103-130 µm, length (exclusive of septa) 80-102 µm, length 46-70 µm, apical horn 22-26 µm
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Original description: Stover and Helby, 1987, p. 238-241
Cysts proximochorate, ellipsoidal to elongate ellipsoidal with a prominent apical horn formed by the periphragm (Fig.12E,F,I,J). Cyst wall uniformly to randomly pitted over most of the surface; pits circular, elliptical and irregularly rounded, less than 2 Ám in diameter (most are less than 1.5 Ám), distances between them varying from a fraction of a micron to 3 Ám (Fig. I IG,K). Sculpturing tends to become finer towards the poles and may be absent across the apices. Cyst wall about 3-5 Ám in the equatorial area and generally thinning slightly polewards. Separation of the wall layers usually discernible only where parasutural septa or folds (normally the former) formed (Fig. 1 2G) . Septa or folds smooth or faintly ornamented and from 4-8 Ám in height. Crests of septa with irregularly spaced, pointed or rounded projections of less than 1 Ám in height. On the epicyst, parasutural features delineating generally 3 apical paraplates, the anterior and lateral margins of 5 precingular paraplates, and the lateral margins of a combined apical/precingular paraplate (Fig . I OA-D). No indications of cingular paraplates. On the hypocyst, parasutural features define the posterior and lateral margins of 5 postcingular paraplates, and outline the antapical paraplate. A posterior intercalary, a posterior sulcal, and an additional postcingular paraplate completely or partly delimited on some specimens. Paratabulation formula: 3-4?', 5-6'', Xc, 5-6''', 0-1p, 1'''', 0-2s. Five normally determinable postcingular paraplates interpreted as reflecting plates 2''' to 6''' (Fig. 10). The antapical paraplate occupies the posterior ventral surface and has a single, hollow, distally closed, intratabular process 8-10 Ám long and about 4 Ám wide (Figs I IC,H, 12H,L). Precingular archeopyle formed by release of paraplate 3" only, opening reduced; the operculum generally released completely.
Specimens, exclusive of septa, 80 (90) 102 Ám in length, 46 (52) 70 Ám wide at midlength; apical horn 22-26 Ám long, and the overall length of specimens 103 (112) 130 Ám; 20 specimens measured. Paratabulation. On all specimens of H. postprojecta, the paratabulation is reduced, with most of the reduction occurring in the cingular and ventral areas. The dorsal apical paraplates, considered equivalent to plates 2'' and 3'', are usually clearly and completely delimited, whereas the ventral apical paraplates are consistently incompletely delimited. The septum separating 1' and 4' may be present or absent, as may the one between 1' and the parasulcus; no septum was observed between 4' and 6''. The adcingular boundaries of all precingular and postcingular paraplates are unexpressed, which leaves a relatively broad, circumcentral area free of paratabulation. On the hypocyst, septa between the ventral postcingular paraplates and the sulcal area are, at best, partly developed. Only on an occasional specimen are the posterior intercalary and posterior sulcal paraplates outlined completely. In so far as we can determine, the positions and shapes of the paraplates follow the standard gonyaulacacean pattern.
Affinities:
Stover and Helby, 1987, p. 241: Herendeenia postprojecta differs from H. pisciformis (Cookson & Eisenack) Wiggins 1969 in having a single intratabular process on the antapical paraplate, a pitted ornamentation rather than one consisting of Drojections, and a longer and narrower apical horn. Herendeenia alaskaensis (Stover & Evitt) Stover & Helby (1987), which is similar to the elongate ellipsoidal forms of H. postprojecta, differs in lacking the intratabular process, and in having a thinner cyst wall which is granulate rather than pitted.
Holotype: Stover and Helby, 1987, fig.11A-E
Locus typicus: Exmouth Plateau, W Australia
Stratum typicum: Hauterivian-Aptian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Herendeenia postprojecta Stover and Helby, 1987c, differs from H. pisciformis in having a single intratabular process on the antapical paraplate, which lies on the ventral surface, a pitted ornamentation rather than one consisting of projections, and a longer and narrower apical horn. H. alaskaensis, which is similar to the elongate ellipsoidal forms of H. postprojecta, differs in lacking the intratabular process, and in having a thinner cyst wall which is granulate rather than pitted. Size overall length 103-130 µm, length (exclusive of septa) 80-102 µm, length 46-70 µm, apical horn 22-26 µm
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Original description: Stover and Helby, 1987, p. 238-241
Cysts proximochorate, ellipsoidal to elongate ellipsoidal with a prominent apical horn formed by the periphragm (Fig.12E,F,I,J). Cyst wall uniformly to randomly pitted over most of the surface; pits circular, elliptical and irregularly rounded, less than 2 Ám in diameter (most are less than 1.5 Ám), distances between them varying from a fraction of a micron to 3 Ám (Fig. I IG,K). Sculpturing tends to become finer towards the poles and may be absent across the apices. Cyst wall about 3-5 Ám in the equatorial area and generally thinning slightly polewards. Separation of the wall layers usually discernible only where parasutural septa or folds (normally the former) formed (Fig. 1 2G) . Septa or folds smooth or faintly ornamented and from 4-8 Ám in height. Crests of septa with irregularly spaced, pointed or rounded projections of less than 1 Ám in height. On the epicyst, parasutural features delineating generally 3 apical paraplates, the anterior and lateral margins of 5 precingular paraplates, and the lateral margins of a combined apical/precingular paraplate (Fig . I OA-D). No indications of cingular paraplates. On the hypocyst, parasutural features define the posterior and lateral margins of 5 postcingular paraplates, and outline the antapical paraplate. A posterior intercalary, a posterior sulcal, and an additional postcingular paraplate completely or partly delimited on some specimens. Paratabulation formula: 3-4?', 5-6'', Xc, 5-6''', 0-1p, 1'''', 0-2s. Five normally determinable postcingular paraplates interpreted as reflecting plates 2''' to 6''' (Fig. 10). The antapical paraplate occupies the posterior ventral surface and has a single, hollow, distally closed, intratabular process 8-10 Ám long and about 4 Ám wide (Figs I IC,H, 12H,L). Precingular archeopyle formed by release of paraplate 3" only, opening reduced; the operculum generally released completely.
Specimens, exclusive of septa, 80 (90) 102 Ám in length, 46 (52) 70 Ám wide at midlength; apical horn 22-26 Ám long, and the overall length of specimens 103 (112) 130 Ám; 20 specimens measured. Paratabulation. On all specimens of H. postprojecta, the paratabulation is reduced, with most of the reduction occurring in the cingular and ventral areas. The dorsal apical paraplates, considered equivalent to plates 2'' and 3'', are usually clearly and completely delimited, whereas the ventral apical paraplates are consistently incompletely delimited. The septum separating 1' and 4' may be present or absent, as may the one between 1' and the parasulcus; no septum was observed between 4' and 6''. The adcingular boundaries of all precingular and postcingular paraplates are unexpressed, which leaves a relatively broad, circumcentral area free of paratabulation. On the hypocyst, septa between the ventral postcingular paraplates and the sulcal area are, at best, partly developed. Only on an occasional specimen are the posterior intercalary and posterior sulcal paraplates outlined completely. In so far as we can determine, the positions and shapes of the paraplates follow the standard gonyaulacacean pattern.
Affinities:
Stover and Helby, 1987, p. 241: Herendeenia postprojecta differs from H. pisciformis (Cookson & Eisenack) Wiggins 1969 in having a single intratabular process on the antapical paraplate, a pitted ornamentation rather than one consisting of Drojections, and a longer and narrower apical horn. Herendeenia alaskaensis (Stover & Evitt) Stover & Helby (1987), which is similar to the elongate ellipsoidal forms of H. postprojecta, differs in lacking the intratabular process, and in having a thinner cyst wall which is granulate rather than pitted.