1.6 Monosaccate Forms
13
The former was proposed by Leschik for monosaccate forms possessing a trilete
proximal mark, and the latter for monosaccate forms devoid of a proximal mark.
Bharadwaj (1953) emended vesiculomonoraditi for monosaccate forms and he
introduced Araditi (Bharadwaj, 1953) for alete monosaccate forms. In the present
study further sub-division of the monosaccites is rejected on the following grounds:
It is evident from many monosaccate forms that the proximal tetrad mark varies
from specimen to specimen, from monolete to dilete or trilete, or is absent altogether
as a recognisable distinct feature. This morphological feature was traced during the
present study by examining over 300 specimens of Parasaccites gondwanensis from
one sample (see Fig. 51). Therefore, the monosaccate forms in this book are treated
as one group, and no further division of the monosaccates is adopted as this would
inevitably lead to the splitting of form genera and even species, rendering it useless in
comparing microfloras from different sediments of the same age, and thus misleading
in stratigraphic correlations.
Hart’s (1965) classification of monosaccate forms is based on the ektexine mode
of detachment, thus sub-dividing the group into two infra-turmae:
1. DIPOLSACCITI—are “monosaccites in which the saccus is attached on both the
proximal and distal hemisphere of the central body” (Hart 1965).
2. MONPOLSACCITI—are “monosaccites in which the saccus is attached either
proximally or distally to the central body, but not on both surfaces” (Hart 1965).
In the present study only one monosaccate form genus seems to be a monpolsacciti; for example, Densipollenites Bharadwaj, and therefore Hart’s sub-division of the
monosaccate forms is not adopted. It is not considered useful to erect a supra-generic
group for the sole accommodation of one genus. Nevertheless, Hart’s classification
in general is adopted on principal grounds; it is based on the consistent feature in a
saccate form, namely, the mode of ektexine detachment and formation of the saccus.
Interestingly, when fossil saccate pollen grains are compared to living saccate forms
the same morphology is valid. On the other hand, the proximal tetrad mark used
for sub-division by other authors is an inconsistent characteristic in saccate forms.
Furthermore, recent studies of pollen extracted from fossil pollen sacs demonstrated
enormous variation in their tetrad mark morphology from mature to immature pollen
within the same pollen sac. Furthermore, these monosaccate pollen were classified
under Cordaitales, and have been shown to be alete, monolete or trilete. Saccate pollen
of living plants show similar diversity in the way of number of sacci (Fig. 1.3a–c).
1.7 Disaccate Forms
The disaccates were further sub-divided by Leschik (1955, 1965) into two series:
1. DISACCITRILETES
2. DISACCI-ATRILETES
13
The former was proposed by Leschik for monosaccate forms possessing a trilete
proximal mark, and the latter for monosaccate forms devoid of a proximal mark.
Bharadwaj (1953) emended vesiculomonoraditi for monosaccate forms and he
introduced Araditi (Bharadwaj, 1953) for alete monosaccate forms. In the present
study further sub-division of the monosaccites is rejected on the following grounds:
It is evident from many monosaccate forms that the proximal tetrad mark varies
from specimen to specimen, from monolete to dilete or trilete, or is absent altogether
as a recognisable distinct feature. This morphological feature was traced during the
present study by examining over 300 specimens of Parasaccites gondwanensis from
one sample (see Fig. 51). Therefore, the monosaccate forms in this book are treated
as one group, and no further division of the monosaccates is adopted as this would
inevitably lead to the splitting of form genera and even species, rendering it useless in
comparing microfloras from different sediments of the same age, and thus misleading
in stratigraphic correlations.
Hart’s (1965) classification of monosaccate forms is based on the ektexine mode
of detachment, thus sub-dividing the group into two infra-turmae:
1. DIPOLSACCITI—are “monosaccites in which the saccus is attached on both the
proximal and distal hemisphere of the central body” (Hart 1965).
2. MONPOLSACCITI—are “monosaccites in which the saccus is attached either
proximally or distally to the central body, but not on both surfaces” (Hart 1965).
In the present study only one monosaccate form genus seems to be a monpolsacciti; for example, Densipollenites Bharadwaj, and therefore Hart’s sub-division of the
monosaccate forms is not adopted. It is not considered useful to erect a supra-generic
group for the sole accommodation of one genus. Nevertheless, Hart’s classification
in general is adopted on principal grounds; it is based on the consistent feature in a
saccate form, namely, the mode of ektexine detachment and formation of the saccus.
Interestingly, when fossil saccate pollen grains are compared to living saccate forms
the same morphology is valid. On the other hand, the proximal tetrad mark used
for sub-division by other authors is an inconsistent characteristic in saccate forms.
Furthermore, recent studies of pollen extracted from fossil pollen sacs demonstrated
enormous variation in their tetrad mark morphology from mature to immature pollen
within the same pollen sac. Furthermore, these monosaccate pollen were classified
under Cordaitales, and have been shown to be alete, monolete or trilete. Saccate pollen
of living plants show similar diversity in the way of number of sacci (Fig. 1.3a–c).
1.7 Disaccate Forms
The disaccates were further sub-divided by Leschik (1955, 1965) into two series:
1. DISACCITRILETES
2. DISACCI-ATRILETES