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Pannosiella perforata
Pannosiella perforata Batten and Lister, 1988
Holotype: Batten and Lister, 1988, fig.2f
Locus typicus: Cowleaze Chine Member of the Vectis Formation, Isle of Wight
Stratum typicum: Barremian
Original diagnosis: Batten and Lister, 1988, p.348
Skolochorate cyst with a small, subspherical to ovoid body, sometimes displaying a slight, rounded to blunt, apical prominence; maximum diameter of central body 20(26)34 x 20(29)35 µm, length of processes 17(24)32 µm, maximum diameter of cyst including processes 60-75 µm (20 specimens). Phragma two-layered, composed of a very thin (<0.5 µm), finely granular to pitted periphragm closely adpressed to a thicker (1.2 µm) endophragm. Periphragm gives rise to numerous, long, flexuous, processes which appear perforate to microreticulate in transmitted light but only scabrate and slightly pitted under a scanning electron microscope. They are of variable morphology, but most are broad, especially at their bases (6-10 µm), flattened, ribbon-like and distally closed. Some are particularly wide and flimsy; others may be simple and narrow (2-3 µm). Irregularly shaped processes with small, lateral, spinose outgrowths along their length are common; they may taper or widen distally and frequently have bi- or trifurcate terminations, giving them a "ragged" appearance. Occasionally they divide halfway, each branch being distally bifurcate. One type of process may predominate in individuals but usually simple processes are interspersed with irregularly shaped elements. Paratabular alignment is detectable on some cysts in a favourable orientation but is not usually evident in small specimens when processes are dense. Archeopyle precingular but commonly undeveloped or obscured by rupturing of epicyst.
Affinities:
Batten and Lister, 1988, p. 348: The flimsy, flexuous, irregularly shaped processes with their spinose edges and variously branched terminations, are somewhat reminiscent of tattered strips of rag. A gonyaulacacean distribution of processes may be discernible when the cysts are correctly orientated, which is easy to do only when an apical boss can be detected. A complete paratabulation has not, however, been possible to determine because of the obscuring effect of the numerous fine processes that are also present. In some specimens there is no apparent alignment of processes. When these consist entirely of narrow, simple elements it is possible that their distribution is not linked to paratabulation. It is clear that theperforation / microreticulation of the processes as seen in transmitted light is internal because it is not visible under a scanning electron microscope.
Holotype: Batten and Lister, 1988, fig.2f
Locus typicus: Cowleaze Chine Member of the Vectis Formation, Isle of Wight
Stratum typicum: Barremian
Original diagnosis: Batten and Lister, 1988, p.348
Skolochorate cyst with a small, subspherical to ovoid body, sometimes displaying a slight, rounded to blunt, apical prominence; maximum diameter of central body 20(26)34 x 20(29)35 µm, length of processes 17(24)32 µm, maximum diameter of cyst including processes 60-75 µm (20 specimens). Phragma two-layered, composed of a very thin (<0.5 µm), finely granular to pitted periphragm closely adpressed to a thicker (1.2 µm) endophragm. Periphragm gives rise to numerous, long, flexuous, processes which appear perforate to microreticulate in transmitted light but only scabrate and slightly pitted under a scanning electron microscope. They are of variable morphology, but most are broad, especially at their bases (6-10 µm), flattened, ribbon-like and distally closed. Some are particularly wide and flimsy; others may be simple and narrow (2-3 µm). Irregularly shaped processes with small, lateral, spinose outgrowths along their length are common; they may taper or widen distally and frequently have bi- or trifurcate terminations, giving them a "ragged" appearance. Occasionally they divide halfway, each branch being distally bifurcate. One type of process may predominate in individuals but usually simple processes are interspersed with irregularly shaped elements. Paratabular alignment is detectable on some cysts in a favourable orientation but is not usually evident in small specimens when processes are dense. Archeopyle precingular but commonly undeveloped or obscured by rupturing of epicyst.
Affinities:
Batten and Lister, 1988, p. 348: The flimsy, flexuous, irregularly shaped processes with their spinose edges and variously branched terminations, are somewhat reminiscent of tattered strips of rag. A gonyaulacacean distribution of processes may be discernible when the cysts are correctly orientated, which is easy to do only when an apical boss can be detected. A complete paratabulation has not, however, been possible to determine because of the obscuring effect of the numerous fine processes that are also present. In some specimens there is no apparent alignment of processes. When these consist entirely of narrow, simple elements it is possible that their distribution is not linked to paratabulation. It is clear that theperforation / microreticulation of the processes as seen in transmitted light is internal because it is not visible under a scanning electron microscope.