Back
Areoligera crescentis
Areoligera crescentis, Damassa, 1979
Holotype: Damassa, 1979, pl.1, figs.9-11
Age: Early Paleocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Damassa, 1979]:
Diagnosis:
Cyst dorsoventrally compressed, paratabulation indicated by arcuate, annulate or rectilinear penitabular process complexes of variable development. Arcuate process development along anterior margins of precingular paraplates and posterior margins of postcingular paraplates. Apical and antapical paraplated delineated by annulate process complexes; cingular paraplates along lateral margins of cysts delineated by rectilinear process complexes. Remainder of ventral and dorsal surfaces devoid of processes.
Archeopyle Type (tA); operculum simple, free.
Description:
Chorate cysts, dorsoventrally compressed; 57-73 μm in length (mean = 62 μm of 12 specimens), 62-75 μm in width (mean = 67 μm of 12 specimens). Paratabulation indicated by arcuate, annulate or rectilinear penitabulation process complexes. Arcuate process complexes are developed along the anterior margins of the precingular paraplates, and the posterior margins of the postcingular paraplates. The posterior intercalary paraplate is also represented by an arcuate process complex (Pl. 1, figs. 9,12). Sulcal paraplates not presented except the anterior sulcul paraplate, whose anterior margin bears a small process complex. Rectilinear paracingular process complexes are restricted to the lateral margins of the cysts, and are not present on the middorsal or midventral surfaces. The apical and antapical paraplates are delineated by annulate process complexes (pl. 1, fig. 2-8). Individual processes within the process complexes connected proximally by low ridge-like features; process shape variable, some are slender, cylindrical, with simple, capitate, or bifurcate tips, while others are blade-like or membranous highly perforate structures resulting from the fusion of several processes. Processes up to 20 μm in height; tips commonly not connected distally. More than one type of process may occur on a single specimen. surface of cyst spongy or foveolate, best seen on ventral surface (Pl. 1, fig. 12).
Archeopyple Type (tA), formed by loss of four paraplates. Opercula about 45x55 μm, simple, free.
Paratabulation: 4', 6'', ?4c, xs, 1p, 5''', 1''''. Inferred thecal tabulation: 4', 6'', 6c, ?5s, 1p, 6''',1''''.
Affinities/Remarks:
Areoligera crescentis, like other species in this genus, shows a high degree of morphologic variability in the form and development of process complexes. The apical and antapical process complexes show the least amount of variation, and are present as complete annulate complexes. The first and fourth process complexes may be fused along their common side or connected toward the apex (Pl. 1, fig. 3-8). Process complexes on the ventral and dorsal surfaces indicate a partial paratabulation: process complexes on paraplates 1''-6'' and 2'''-5''' are generally distinguishable, those on paraplates 1c, or 2c and 4c or 5c may be developed along the compressed lateral margins of the cyst, and paraplate 1p is commonly indicated by an arcuate process complex. Of the sulcul paraplates, only the antarior sulcal is delineated by a process complex (Pl. 1, fig. 9, 12). The posterior sulcul paraplate can be recognized occasionally by a process complex near the antapex. This species can be distinguished from A. coronata, whose processes are similar to those of A. crescentis, by the restriction of the process complexes on the dorsal surface to the anterior and posterior regions of the cyst (see Eaton, 1976, p. 242-245 for a discussion of A. coronata and related species). The species of Areoligera reported by Drugg (1967, p. 20-21) as A. tenuicapillata and A. volata differ from A. crescentis in having the pre- and postcingular paraplates on the dorsal surface delineated by annulate rather the arcuate processes and in having delineated cingular paraplates.
Holotype: Damassa, 1979, pl.1, figs.9-11
Age: Early Paleocene
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Damassa, 1979]:
Diagnosis:
Cyst dorsoventrally compressed, paratabulation indicated by arcuate, annulate or rectilinear penitabular process complexes of variable development. Arcuate process development along anterior margins of precingular paraplates and posterior margins of postcingular paraplates. Apical and antapical paraplated delineated by annulate process complexes; cingular paraplates along lateral margins of cysts delineated by rectilinear process complexes. Remainder of ventral and dorsal surfaces devoid of processes.
Archeopyle Type (tA); operculum simple, free.
Description:
Chorate cysts, dorsoventrally compressed; 57-73 μm in length (mean = 62 μm of 12 specimens), 62-75 μm in width (mean = 67 μm of 12 specimens). Paratabulation indicated by arcuate, annulate or rectilinear penitabulation process complexes. Arcuate process complexes are developed along the anterior margins of the precingular paraplates, and the posterior margins of the postcingular paraplates. The posterior intercalary paraplate is also represented by an arcuate process complex (Pl. 1, figs. 9,12). Sulcal paraplates not presented except the anterior sulcul paraplate, whose anterior margin bears a small process complex. Rectilinear paracingular process complexes are restricted to the lateral margins of the cysts, and are not present on the middorsal or midventral surfaces. The apical and antapical paraplates are delineated by annulate process complexes (pl. 1, fig. 2-8). Individual processes within the process complexes connected proximally by low ridge-like features; process shape variable, some are slender, cylindrical, with simple, capitate, or bifurcate tips, while others are blade-like or membranous highly perforate structures resulting from the fusion of several processes. Processes up to 20 μm in height; tips commonly not connected distally. More than one type of process may occur on a single specimen. surface of cyst spongy or foveolate, best seen on ventral surface (Pl. 1, fig. 12).
Archeopyple Type (tA), formed by loss of four paraplates. Opercula about 45x55 μm, simple, free.
Paratabulation: 4', 6'', ?4c, xs, 1p, 5''', 1''''. Inferred thecal tabulation: 4', 6'', 6c, ?5s, 1p, 6''',1''''.
Affinities/Remarks:
Areoligera crescentis, like other species in this genus, shows a high degree of morphologic variability in the form and development of process complexes. The apical and antapical process complexes show the least amount of variation, and are present as complete annulate complexes. The first and fourth process complexes may be fused along their common side or connected toward the apex (Pl. 1, fig. 3-8). Process complexes on the ventral and dorsal surfaces indicate a partial paratabulation: process complexes on paraplates 1''-6'' and 2'''-5''' are generally distinguishable, those on paraplates 1c, or 2c and 4c or 5c may be developed along the compressed lateral margins of the cyst, and paraplate 1p is commonly indicated by an arcuate process complex. Of the sulcul paraplates, only the antarior sulcal is delineated by a process complex (Pl. 1, fig. 9, 12). The posterior sulcul paraplate can be recognized occasionally by a process complex near the antapex. This species can be distinguished from A. coronata, whose processes are similar to those of A. crescentis, by the restriction of the process complexes on the dorsal surface to the anterior and posterior regions of the cyst (see Eaton, 1976, p. 242-245 for a discussion of A. coronata and related species). The species of Areoligera reported by Drugg (1967, p. 20-21) as A. tenuicapillata and A. volata differ from A. crescentis in having the pre- and postcingular paraplates on the dorsal surface delineated by annulate rather the arcuate processes and in having delineated cingular paraplates.