90
2 Systematic Descriptions
Fig. 2.65 Distal face, sacci
roots folded
Amb oval to sub-circular. Asaccate striatiti. Oroximal face striated. Taeniae
numerous, about 15 or more extending on to distal face to about half way to
centre of grain, covering about 1/3 of the pollen grain length on each side of the
cappula. Nexine thin, barely detectable, folds along cappula. Structure of ektexine
intra-granulate to intra-verrucate.
Dimensions: Long axis: 50–90 µ (10 specimens measured).
Remarks: A form which very closely resembles V. scutata described above has
been recorded and described by Backhouse (1991) under Tiwariasporites simplex
(Maheshwari and Kar1967). V. scutata-type pollen has also been recorded from
the Permian of S. Africa (Anderson 1977) and Permian of Australia (Foster 1979)
under different names.
Turma: Plicates (Naumova 1937) (Potonie 1960).
The PLICATES are sub-divided into three sub-turmae: 1.The PREACOLPATES
(Potonie and Kremp 1955) to accommodate monosulcate pollen grains with a
tetrad mark: 2. The POLYPLICATES (Erdtman 1955) to accommodate pollen
grains with more than one groove or furrow running parallel to the long axis of
the grain.
Chasmapollenites is described in the present study under sub-turma POLYPLICATES. It is justified by the fact that these pollen grains belong to a definite group
of gymnosperms, namely the Gnetales.
Monocolpate grains such as Cycadopites (Wodehouse, Wilson and Webster
1946) are described in the present study under MONOCOLPATES (Iversen and
Troels-Smith 1950). Hart (1965a, b) described Vittatina under group STRIATITI
noting the difference though, namely that this genus is distinguished by the
absence of sacci or the presence of only rudimentary sacci. It is emphasised
2 Systematic Descriptions
Fig. 2.65 Distal face, sacci
roots folded
Amb oval to sub-circular. Asaccate striatiti. Oroximal face striated. Taeniae
numerous, about 15 or more extending on to distal face to about half way to
centre of grain, covering about 1/3 of the pollen grain length on each side of the
cappula. Nexine thin, barely detectable, folds along cappula. Structure of ektexine
intra-granulate to intra-verrucate.
Dimensions: Long axis: 50–90 µ (10 specimens measured).
Remarks: A form which very closely resembles V. scutata described above has
been recorded and described by Backhouse (1991) under Tiwariasporites simplex
(Maheshwari and Kar1967). V. scutata-type pollen has also been recorded from
the Permian of S. Africa (Anderson 1977) and Permian of Australia (Foster 1979)
under different names.
Turma: Plicates (Naumova 1937) (Potonie 1960).
The PLICATES are sub-divided into three sub-turmae: 1.The PREACOLPATES
(Potonie and Kremp 1955) to accommodate monosulcate pollen grains with a
tetrad mark: 2. The POLYPLICATES (Erdtman 1955) to accommodate pollen
grains with more than one groove or furrow running parallel to the long axis of
the grain.
Chasmapollenites is described in the present study under sub-turma POLYPLICATES. It is justified by the fact that these pollen grains belong to a definite group
of gymnosperms, namely the Gnetales.
Monocolpate grains such as Cycadopites (Wodehouse, Wilson and Webster
1946) are described in the present study under MONOCOLPATES (Iversen and
Troels-Smith 1950). Hart (1965a, b) described Vittatina under group STRIATITI
noting the difference though, namely that this genus is distinguished by the
absence of sacci or the presence of only rudimentary sacci. It is emphasised