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Paragonyaulacysta borealis
Paragonyaulacysta? borealis (Brideaux and Fisher, 1976) Stover and Evitt, 1978
Originally Pareodinia, subsequently Paragonyaulacysta, thirdly (and now) Paragonyaulacysta?. Below, 1990 questionably included this species in Paragonyaulacysta.
Holotype: Brideaux and Fisher, 1976, pl.3, fig.3,6,8
Locus typicus: Machenzie District, Canada
Stratum typicum: Late Oxfordian-Berriasian
Original diagnosis: Brideaux and Fisher, 1976, p. 21: Pareodinia borealis
Cyst length greater than maximum width; apex prolonged into a short, stout, tapering apical horn; antapex rounded. Periphragm and endophragm closely appressed. Periphragm surface smooth or scabrate, bearing low, narrow sutures that outline a reflected tabulation scheme, imperfectly determined as ?4", 2a, 6", 6c, 5""" -?6""", 1"""", ?1p. Archeopyle intercalary, probably formed by the loss of two polygonal reflected intercalary plates; operculum apparently simple. Cingulum outlined by low sutures; six cingular reflected plates, transversely elongated and polygonal. Sulcus not observed.
Original description: Brideuax and Fisher, 1976, p. 21: Pareodinia borealis
The length of the cyst is from one and one-half to two times the width; the maximum width occurs at the latitude of the cingulum. The outline of the cyst is somewhat droplet-shaped, with a short, stout and tapering apical horn and rounded antapex.
The periphragm is membranous, about 0.25 to 0.5 µm thick in optical section, and forms the low, narrow sutures which are most evident where the gonal portions of the sutures project slightly at the periphery. The endophragm is closely appressed to the periphragm and is about 1µm thick in optical section and, therefore, slightly thicker than the periphragm. The surface of the periphragm is smooth or scabrate; the surface of the endophragm is smooth. The periphragm occasionally bears a fine, discontinuous, membranous patchwork, which may represent remnants of a kalyptra (cf. Gocht, 1970).
The archeopyle is intercalary in position. The archeopyle and operculum are not well represented on available material, but several specimens appear to possess a Type 2I archeopyle (Evitt, 1967), formed by the loss of two reflected intercalary plates, as evidenced by the outline of the principal archeopyle sutures. The simple operculum may be observed indistinctly in place in several specimens.
The sutural ridges of the periphragm outline a reflected tabulation, imperfectly developed on any one specimen, which corresponds to the scheme ?4", 2a, 6", 6c, 5""" -?6""", 1p, 1"""". The reflected apical plate series is the least readily discernible.
The cingulum consists of six reflected plates transversely elongate and polygonal in shape. The ventral terminations of the cingulum are not clearly exhibited on material available, but the cingulum appears offset about one-half to one cingulum width (from 4-8 µm). The sulcus was not clearly observed.
Dimensions:
(47 specimens) Overall length, 53-95 µm; overall width, 36-61 µm.
Affinities:
Brideaux and Fisher, 1976, p. 21: Pareodinia borealis is distinguished from Pareodinia capizzosa by its shape and smooth periphragm, and by its generally smaller size range. Pareodinia borealis is comparable in size, range and shape to Pareodinia ceratophora (Deflandre) emend. Gocht (1970), but differs in possessing a defined, distinct to indistinct reflected tabulation pattern. Parts of the reflected cingulum are sometimes visible on P. ceratophora (see, for example, Gocht, 1970, Pl. 35, fig. 5), but extensive reflected tabulation exhibited by P. borealis has never been reported (Deflandre, 1947- Valensi, 1953- Gocht, 1970). The periphragm surface of P. borealis sp. nov. is smooth or scabrate, whereas that of P. ceratophora is often finely granulate. Finally, P. borealis sp. nov. is distinctly two-layered in construction, whereas P. ceratophora appears to possess an autophragm.
Originally Pareodinia, subsequently Paragonyaulacysta, thirdly (and now) Paragonyaulacysta?. Below, 1990 questionably included this species in Paragonyaulacysta.
Holotype: Brideaux and Fisher, 1976, pl.3, fig.3,6,8
Locus typicus: Machenzie District, Canada
Stratum typicum: Late Oxfordian-Berriasian
Original diagnosis: Brideaux and Fisher, 1976, p. 21: Pareodinia borealis
Cyst length greater than maximum width; apex prolonged into a short, stout, tapering apical horn; antapex rounded. Periphragm and endophragm closely appressed. Periphragm surface smooth or scabrate, bearing low, narrow sutures that outline a reflected tabulation scheme, imperfectly determined as ?4", 2a, 6", 6c, 5""" -?6""", 1"""", ?1p. Archeopyle intercalary, probably formed by the loss of two polygonal reflected intercalary plates; operculum apparently simple. Cingulum outlined by low sutures; six cingular reflected plates, transversely elongated and polygonal. Sulcus not observed.
Original description: Brideuax and Fisher, 1976, p. 21: Pareodinia borealis
The length of the cyst is from one and one-half to two times the width; the maximum width occurs at the latitude of the cingulum. The outline of the cyst is somewhat droplet-shaped, with a short, stout and tapering apical horn and rounded antapex.
The periphragm is membranous, about 0.25 to 0.5 µm thick in optical section, and forms the low, narrow sutures which are most evident where the gonal portions of the sutures project slightly at the periphery. The endophragm is closely appressed to the periphragm and is about 1µm thick in optical section and, therefore, slightly thicker than the periphragm. The surface of the periphragm is smooth or scabrate; the surface of the endophragm is smooth. The periphragm occasionally bears a fine, discontinuous, membranous patchwork, which may represent remnants of a kalyptra (cf. Gocht, 1970).
The archeopyle is intercalary in position. The archeopyle and operculum are not well represented on available material, but several specimens appear to possess a Type 2I archeopyle (Evitt, 1967), formed by the loss of two reflected intercalary plates, as evidenced by the outline of the principal archeopyle sutures. The simple operculum may be observed indistinctly in place in several specimens.
The sutural ridges of the periphragm outline a reflected tabulation, imperfectly developed on any one specimen, which corresponds to the scheme ?4", 2a, 6", 6c, 5""" -?6""", 1p, 1"""". The reflected apical plate series is the least readily discernible.
The cingulum consists of six reflected plates transversely elongate and polygonal in shape. The ventral terminations of the cingulum are not clearly exhibited on material available, but the cingulum appears offset about one-half to one cingulum width (from 4-8 µm). The sulcus was not clearly observed.
Dimensions:
(47 specimens) Overall length, 53-95 µm; overall width, 36-61 µm.
Affinities:
Brideaux and Fisher, 1976, p. 21: Pareodinia borealis is distinguished from Pareodinia capizzosa by its shape and smooth periphragm, and by its generally smaller size range. Pareodinia borealis is comparable in size, range and shape to Pareodinia ceratophora (Deflandre) emend. Gocht (1970), but differs in possessing a defined, distinct to indistinct reflected tabulation pattern. Parts of the reflected cingulum are sometimes visible on P. ceratophora (see, for example, Gocht, 1970, Pl. 35, fig. 5), but extensive reflected tabulation exhibited by P. borealis has never been reported (Deflandre, 1947- Valensi, 1953- Gocht, 1970). The periphragm surface of P. borealis sp. nov. is smooth or scabrate, whereas that of P. ceratophora is often finely granulate. Finally, P. borealis sp. nov. is distinctly two-layered in construction, whereas P. ceratophora appears to possess an autophragm.