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Hystrichostrogylon borisii
Hystrichostrogylon borisii Schioler, 1993
Holotype: Schioler, 1993, pl.1, fig.7
Paratype: Schioler, 1993
Locus typicus: Well M-lOx, Dan Field, Danish North Sea
Stratum typicum: Latest Maastrichtian to Early Danian
Original diagnosis: Schioler, 1993, p.106, 108
A camocavate gonyaulacoid cyst in which the periphragm and endophragm are appressed on the dorsal hemisphere. The ventral pericoel opens to the exterior through a large rounded midventral claustrum which approximately equals the radius of the endophragm in diameter. The periphragm is smooth, the endophragm is ornamented with granulae, verrucae or vermiculae.
Original description: Schioler, 1993, p.108
Camocavate cyst. The periphragm and endophragm are subspherical; the periphragm is appressed to the endophragm on the dorsal hemisphere. Ventrally a pericoel separates the periphragm from the endophragm. The pericoel communicates to the exterior through a subcircular claustrum in the periphragm. The claustrum occupies a midventral position and is approximately equal in size to the radius of the endophragm. The periphragm is smooth. Bi- and trifurcating processes with bifid terminations are present on the periphragm; their paratabular position was not determined. In areas where peri- and endophragm are separated, the length of the process stems is inversely proportional to the distance between the peri- and endophragm (Pl. 1, fig. 9; Pl. 2, figs 2, 3). The periphragm is smooth. The endophragm is granulate, verrucate or vermiculate (height of orna-mentation: 0.5 - 1.5 µm). The size and type of the ornament are constant within a sample, but vary from one group of samples to another. The archaeopyle type is P(3) and the operculum is free. The paracingulum is often indicated by equatorial folds on the periphragm and by the presence of low septa between the longer processes. A parasulsus was not observed. Apart from paracingulum and archaeopyle the paratabulation is not clearly expressed.
Dimensions:holotyperange and mean
overall length of pericyst73 µm64 (74) 84 µm
overall width of pericyst (lat.)81 µm70 (78) 87 µm
length of endocyst44 µm36 (40) 46 µm
width of endocyst38 µm32 (38) 44 µm
length of processes4-14 µm4-20 µm
Specimens measured. 12
Affinities:
Schioler, 1993, p.108: Hystrichostrogylon borisii differs from
Hystrichostrogylon coninckii Heilmann-Clausen 1985 in having a conspicuously ornamented endophragm. Together with H. coninckii, H. borisii differs from all other species of Hystrichostrogylon in having a large rounded midventral claustrum in the periphragm.
Holotype: Schioler, 1993, pl.1, fig.7
Paratype: Schioler, 1993
Locus typicus: Well M-lOx, Dan Field, Danish North Sea
Stratum typicum: Latest Maastrichtian to Early Danian
Original diagnosis: Schioler, 1993, p.106, 108
A camocavate gonyaulacoid cyst in which the periphragm and endophragm are appressed on the dorsal hemisphere. The ventral pericoel opens to the exterior through a large rounded midventral claustrum which approximately equals the radius of the endophragm in diameter. The periphragm is smooth, the endophragm is ornamented with granulae, verrucae or vermiculae.
Original description: Schioler, 1993, p.108
Camocavate cyst. The periphragm and endophragm are subspherical; the periphragm is appressed to the endophragm on the dorsal hemisphere. Ventrally a pericoel separates the periphragm from the endophragm. The pericoel communicates to the exterior through a subcircular claustrum in the periphragm. The claustrum occupies a midventral position and is approximately equal in size to the radius of the endophragm. The periphragm is smooth. Bi- and trifurcating processes with bifid terminations are present on the periphragm; their paratabular position was not determined. In areas where peri- and endophragm are separated, the length of the process stems is inversely proportional to the distance between the peri- and endophragm (Pl. 1, fig. 9; Pl. 2, figs 2, 3). The periphragm is smooth. The endophragm is granulate, verrucate or vermiculate (height of orna-mentation: 0.5 - 1.5 µm). The size and type of the ornament are constant within a sample, but vary from one group of samples to another. The archaeopyle type is P(3) and the operculum is free. The paracingulum is often indicated by equatorial folds on the periphragm and by the presence of low septa between the longer processes. A parasulsus was not observed. Apart from paracingulum and archaeopyle the paratabulation is not clearly expressed.
Dimensions:holotyperange and mean
overall length of pericyst73 µm64 (74) 84 µm
overall width of pericyst (lat.)81 µm70 (78) 87 µm
length of endocyst44 µm36 (40) 46 µm
width of endocyst38 µm32 (38) 44 µm
length of processes4-14 µm4-20 µm
Specimens measured. 12
Affinities:
Schioler, 1993, p.108: Hystrichostrogylon borisii differs from
Hystrichostrogylon coninckii Heilmann-Clausen 1985 in having a conspicuously ornamented endophragm. Together with H. coninckii, H. borisii differs from all other species of Hystrichostrogylon in having a large rounded midventral claustrum in the periphragm.