Back
Alisocysta reticulata
From Fensome et al., 2019:
Alisocysta reticulata, Damassa, 1979b, p.196,198,200, pl.3, figs.1–6; pl.4, figs.4–5; text-fig.3.
Holotype: Damassa, 1979b, pl.4, figs.4–5; text-fig.3.
NOW Eisenackia.
Originally Alisocysta, subsequently (and now) Eisenackia.
Age: Early Paleocene.
Locus typicus: Franciscan Complex, California, USA
---------------------------------------------------------------------------------------------------
Original description: [Damassa, 1979, p. 196, 198, 200]:
Diagnosis:
Cyst subspherical to ovoidal; paratabulation indicated by low penitabular ridges. Intratabular ornamentation resembling a low reticulum; reticulation may extend into the parasutural areas.
Archeopyle Type (tA), operculum simple, free.
Description:
Cyst subspherical to ovoidal, averaging 55 µm in length, 51µm in width.
Paratabulation indicated by thin penitabular ridges 2-3 µm in height.
Intratabular regions are ornamented with reticulate features of low relief (about 1-2 µm in height). Reticulation may also be developed to a lesser degree in the parasutural areas. Ends of paracingulum offset by a distance slightly less than the width of the paracingulum.
Archeoyle Type (tA), operculum simple, free, about 24 x 29 µm.
Parasulcal notch conspicuously developed. Anterior sulcal paraplate slender and subtriangular in outline. Paraplate 6'' reduced with respect to others in the precingular series. Cingular paraplates indicated by elongate, subrectangular penitabular ridges. Postcingular paraplates completely developed although paraplate 1''' is small and inconspicuous. Five sulcal paraplates indicated. Antapical paraplate pentagonal in shape, bordered by 1p, 3''', 4''', 5''', ps.
Paratabulation: 4', 6'', 6c, 5s, 1p, 6''', 1''''. Inferred thecal tabulation: as above.
Remarks:
The intratabular reticulations of A. reticulata are continuous with the penitabular ridges. Parasutural areas are commonly reticulate as well, but in most individuals the parasutural reticulations are more subdued than those within the penitabular ridges.
Affinities:
Alisocysta reticulata is very similar to Eisenackia crassitabulata Deflandre and Cookson 1955. The two species apparently differ only with respect to the degree of development of the intratabular reticulations (R. Helby, pers. comm.). In A. reticulata the reticulate features are low, generally less than half the height of the penitabular ridges, whereas in E. crassitabulata the reticulate structure fills the entire space delineated by the penitabular ridges. Thus in E. crassitabulata the paratabulation is indicated by distinctly positive features ("elevated, platformlike features", Stover and Evitt, 1978, p. 16). A. reticulata can be described in terms of a morphological variation in which penitabular paratabulation is combined with intratabular ornamentation.
It is clear from inspection of illustrated specimens as well as those used in this study that the genera Alisocysta and Eisenackia are identical in paratabulation pattern and type of archeopyle. The configuration of the paraplates on the hypocyst of E. crassitabulata was clearly illustrated by Deflandre and Cookson (1955, Text-Figures 8, 11, 12, 15) and exactly corresponds to that of A. ircumtabulata, as well as to that of A. rugolirata and A. reticulata.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Alisocysta reticulata Damassa, 1979b, has low penitabular ridges, and intratabular ornamentation resembling a low reticulum. The reticulation may extend into the parasutural area. Alisocysta reticulata is closely similar to Eisenackia crassitabulata. The two species differ only with respect to the degree of development of the intratabular reticulations. In A. reticulata, the reticulate features are low, generally less than half the height of the penitabular ridges, whereas in E.crassitabulata, the reticulate structure fills the entire space delineated by the penitabular ridges. Thus in E.crassitabulata the paratabulation is indicated by distinctly positive features, or elevated platform features. Average length 55 µm, average width 51 µm.
Alisocysta reticulata, Damassa, 1979b, p.196,198,200, pl.3, figs.1–6; pl.4, figs.4–5; text-fig.3.
Holotype: Damassa, 1979b, pl.4, figs.4–5; text-fig.3.
NOW Eisenackia.
Originally Alisocysta, subsequently (and now) Eisenackia.
Age: Early Paleocene.
Locus typicus: Franciscan Complex, California, USA
---------------------------------------------------------------------------------------------------
Original description: [Damassa, 1979, p. 196, 198, 200]:
Diagnosis:
Cyst subspherical to ovoidal; paratabulation indicated by low penitabular ridges. Intratabular ornamentation resembling a low reticulum; reticulation may extend into the parasutural areas.
Archeopyle Type (tA), operculum simple, free.
Description:
Cyst subspherical to ovoidal, averaging 55 µm in length, 51µm in width.
Paratabulation indicated by thin penitabular ridges 2-3 µm in height.
Intratabular regions are ornamented with reticulate features of low relief (about 1-2 µm in height). Reticulation may also be developed to a lesser degree in the parasutural areas. Ends of paracingulum offset by a distance slightly less than the width of the paracingulum.
Archeoyle Type (tA), operculum simple, free, about 24 x 29 µm.
Parasulcal notch conspicuously developed. Anterior sulcal paraplate slender and subtriangular in outline. Paraplate 6'' reduced with respect to others in the precingular series. Cingular paraplates indicated by elongate, subrectangular penitabular ridges. Postcingular paraplates completely developed although paraplate 1''' is small and inconspicuous. Five sulcal paraplates indicated. Antapical paraplate pentagonal in shape, bordered by 1p, 3''', 4''', 5''', ps.
Paratabulation: 4', 6'', 6c, 5s, 1p, 6''', 1''''. Inferred thecal tabulation: as above.
Remarks:
The intratabular reticulations of A. reticulata are continuous with the penitabular ridges. Parasutural areas are commonly reticulate as well, but in most individuals the parasutural reticulations are more subdued than those within the penitabular ridges.
Affinities:
Alisocysta reticulata is very similar to Eisenackia crassitabulata Deflandre and Cookson 1955. The two species apparently differ only with respect to the degree of development of the intratabular reticulations (R. Helby, pers. comm.). In A. reticulata the reticulate features are low, generally less than half the height of the penitabular ridges, whereas in E. crassitabulata the reticulate structure fills the entire space delineated by the penitabular ridges. Thus in E. crassitabulata the paratabulation is indicated by distinctly positive features ("elevated, platformlike features", Stover and Evitt, 1978, p. 16). A. reticulata can be described in terms of a morphological variation in which penitabular paratabulation is combined with intratabular ornamentation.
It is clear from inspection of illustrated specimens as well as those used in this study that the genera Alisocysta and Eisenackia are identical in paratabulation pattern and type of archeopyle. The configuration of the paraplates on the hypocyst of E. crassitabulata was clearly illustrated by Deflandre and Cookson (1955, Text-Figures 8, 11, 12, 15) and exactly corresponds to that of A. ircumtabulata, as well as to that of A. rugolirata and A. reticulata.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Alisocysta reticulata Damassa, 1979b, has low penitabular ridges, and intratabular ornamentation resembling a low reticulum. The reticulation may extend into the parasutural area. Alisocysta reticulata is closely similar to Eisenackia crassitabulata. The two species differ only with respect to the degree of development of the intratabular reticulations. In A. reticulata, the reticulate features are low, generally less than half the height of the penitabular ridges, whereas in E.crassitabulata, the reticulate structure fills the entire space delineated by the penitabular ridges. Thus in E.crassitabulata the paratabulation is indicated by distinctly positive features, or elevated platform features. Average length 55 µm, average width 51 µm.