2 Systematic Descriptions
25
Type locality: Western Australia, Collie Basin, Site B Bore, 800
.
Age and occurrence: Upper Permian of Collie and Muja Basins. Abundant in
vitrinite-dominated coals.
Dimensions: 24–60 µ (30 specimens measured).
Discussion: A significant number of Verrucosphaera specimens show a small,
circular pylome-like opening. Sculpture small, underdeveloped and not covering
entire spore in immature specimens. On the other hand, sculpture becomes denser
in mature spores and larger specimens where projections may reach 3 µ. Algal
spores closely resembling Verrucosphaera are found today in fresh water ponds.
Genus Cymatiosphaera (Wetzel 1933; Deflandre 1954)
Diagnosis: Spherical or ellipsoidal. Wall two-layered. Outer membrane divided
into polygonal fields. Inner wall smooth. Corners of polygons are generally
thickened and elevated above spore surface.
Discussion: Cymatiosphaera was first described from the Cretaceous of Germany (Wetzel 1933). The main characteristic of the form as described by Wetzel
was the possession of a “lamellar skin, which is supported by rods”. Deflandre
(1954) interpreted the outer layer as a membrane arranged in a polygonal pattern with thickened angles which appear as rods when observed in lateral view.
The reticulate or polygonal membrane distinguishes Cymatiosphaera from other
acritarchs. Wetzel (in Norris and Sarjeant 1965) suggested a similarity to the radiolarian Dictyospyris based mainly on the reticulate pattern of the outer membrane.
However, Cymatiosphaera is made of organic matter and therefore not a radiolarian. Tiwari (1964) described the same structured acritarch designating it to
Maculatasporites; having sub-spherical test wall, one-layered, made up of mesh
work, suggesting a reticulate pattern, consisting of muri only. The same applies
to Cymatiosphaera; characterised by its mono-layered wall made up of an open
mesh of a reticulum. A thin membrane that is only preserved in some specimen
and missing in many others is a distinct feature. Both morpho-types are present
in the same samples. The wall structure of Maculatasporites resembles members
of the Linotolypydae family (Eisenack 1962). However, the difference is in the
structure of the muri which in Linotolypydae is made of fibres unlike the solid
muri in Maculatasporites/Cymatiosphaera.
Cymatiosphaera gondwanensis (Tiwari) New Comb (Fig. 2.8).
Synonym: Maculatasporites gondwanensis (Tiwari 1964).
Occurrence: Lower to Upper Permian of Collie; Site B bore 1641
; Muja Site D
bore 665-675
.
Description: Spherical to sub-spherical. Reticulate inner layer when membrane
present. Membrane intra-punctate to intra-granulate. In specimen where membrane is missing a hollow reticulum makes up the wall of the spore. Muri about 2
µ thick surrounding a void 6–8 µ across.
Dimensions: 45–80 µ across (20 specimens measured).
25
Type locality: Western Australia, Collie Basin, Site B Bore, 800
.
Age and occurrence: Upper Permian of Collie and Muja Basins. Abundant in
vitrinite-dominated coals.
Dimensions: 24–60 µ (30 specimens measured).
Discussion: A significant number of Verrucosphaera specimens show a small,
circular pylome-like opening. Sculpture small, underdeveloped and not covering
entire spore in immature specimens. On the other hand, sculpture becomes denser
in mature spores and larger specimens where projections may reach 3 µ. Algal
spores closely resembling Verrucosphaera are found today in fresh water ponds.
Genus Cymatiosphaera (Wetzel 1933; Deflandre 1954)
Diagnosis: Spherical or ellipsoidal. Wall two-layered. Outer membrane divided
into polygonal fields. Inner wall smooth. Corners of polygons are generally
thickened and elevated above spore surface.
Discussion: Cymatiosphaera was first described from the Cretaceous of Germany (Wetzel 1933). The main characteristic of the form as described by Wetzel
was the possession of a “lamellar skin, which is supported by rods”. Deflandre
(1954) interpreted the outer layer as a membrane arranged in a polygonal pattern with thickened angles which appear as rods when observed in lateral view.
The reticulate or polygonal membrane distinguishes Cymatiosphaera from other
acritarchs. Wetzel (in Norris and Sarjeant 1965) suggested a similarity to the radiolarian Dictyospyris based mainly on the reticulate pattern of the outer membrane.
However, Cymatiosphaera is made of organic matter and therefore not a radiolarian. Tiwari (1964) described the same structured acritarch designating it to
Maculatasporites; having sub-spherical test wall, one-layered, made up of mesh
work, suggesting a reticulate pattern, consisting of muri only. The same applies
to Cymatiosphaera; characterised by its mono-layered wall made up of an open
mesh of a reticulum. A thin membrane that is only preserved in some specimen
and missing in many others is a distinct feature. Both morpho-types are present
in the same samples. The wall structure of Maculatasporites resembles members
of the Linotolypydae family (Eisenack 1962). However, the difference is in the
structure of the muri which in Linotolypydae is made of fibres unlike the solid
muri in Maculatasporites/Cymatiosphaera.
Cymatiosphaera gondwanensis (Tiwari) New Comb (Fig. 2.8).
Synonym: Maculatasporites gondwanensis (Tiwari 1964).
Occurrence: Lower to Upper Permian of Collie; Site B bore 1641
; Muja Site D
bore 665-675
.
Description: Spherical to sub-spherical. Reticulate inner layer when membrane
present. Membrane intra-punctate to intra-granulate. In specimen where membrane is missing a hollow reticulum makes up the wall of the spore. Muri about 2
µ thick surrounding a void 6–8 µ across.
Dimensions: 45–80 µ across (20 specimens measured).