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Exiguisphaera phragma
Exiguisphaera phragma Duxbury, 1979; emend. Jan du Chêne et al., 1986
Holotype: Duxbury, 1979, pl.2, fig.2-3, text-figs.1A-B; Jan du Chêne et al., 1986(1), pl.35, figs.1-6; Jan du Chêne et al., 1986(2), pl.28, figs.1,3
Locus typicus: Division C 10, Speeton, England
Stratum typicum: Early Hauterivian
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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.
Exiguisphaera phragma Duxbury, 1979a, emend. Jan du Chêne et al., 1986b. According to Jan du Chêne et al. (1986a, p.11), is a proximate, acavate, subspherical cyst without an apical protuberance. The paratabulation is delineated by parasutural septa formed by rows of arches linked distally and with smooth to finely denticulate crests. The autophragm is vacuolar, with very fine perforations on the surface. The intratabular areas are ornamented by short spines, rounded distally and irregularly distributed. The archeopyle is precingular (3" + 4"). Size: 40-53 x 40-50 µm.
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Original diagnosis: Duxbury, 1979, p.199
A small, spheroidal dinoflagellate cyst with a minutely perforate body wall and a reflected tabulation pattern of ?a.cl, 4', 6", ?c, 6''', 1p., ?1p.v., 1''''. This pattern is outlined by sutural crests composed of short, proximally discrete spines which are distally connected by a trabeculum, giving each crest a fencelike appearance. A few small, intratabular spines are usually present. The archeopyle is precingular and involves the displacement of plates 3" and 4".
Observed dimensions. Holotype 45x50 Ám. Overall 53(47)40x50(47)40 Ám. Specimens measured 33.
Affinities:
Duxbury, 1979, p.199: The spheroidal shape of this species causes random orientation of individual specimens. It is therefore rare to encounter individuals clearly demonstrating the main characteristic feature, the two-plate precingular archeopyle. Nevertheless, the fencelike sutural crests are distinctive.
Holotype: Duxbury, 1979, pl.2, fig.2-3, text-figs.1A-B; Jan du Chêne et al., 1986(1), pl.35, figs.1-6; Jan du Chêne et al., 1986(2), pl.28, figs.1,3
Locus typicus: Division C 10, Speeton, England
Stratum typicum: Early Hauterivian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Exiguisphaera phragma Duxbury, 1979a, emend. Jan du Chêne et al., 1986b. According to Jan du Chêne et al. (1986a, p.11), is a proximate, acavate, subspherical cyst without an apical protuberance. The paratabulation is delineated by parasutural septa formed by rows of arches linked distally and with smooth to finely denticulate crests. The autophragm is vacuolar, with very fine perforations on the surface. The intratabular areas are ornamented by short spines, rounded distally and irregularly distributed. The archeopyle is precingular (3" + 4"). Size: 40-53 x 40-50 µm.
--------------------------------------------------
Original diagnosis: Duxbury, 1979, p.199
A small, spheroidal dinoflagellate cyst with a minutely perforate body wall and a reflected tabulation pattern of ?a.cl, 4', 6", ?c, 6''', 1p., ?1p.v., 1''''. This pattern is outlined by sutural crests composed of short, proximally discrete spines which are distally connected by a trabeculum, giving each crest a fencelike appearance. A few small, intratabular spines are usually present. The archeopyle is precingular and involves the displacement of plates 3" and 4".
Observed dimensions. Holotype 45x50 Ám. Overall 53(47)40x50(47)40 Ám. Specimens measured 33.
Affinities:
Duxbury, 1979, p.199: The spheroidal shape of this species causes random orientation of individual specimens. It is therefore rare to encounter individuals clearly demonstrating the main characteristic feature, the two-plate precingular archeopyle. Nevertheless, the fencelike sutural crests are distinctive.