PROGRESS IN PROTOZOOLOGY
PROGRESS IN PROTOZOOLOGY
PROGRESS IN PROTOZOOLOGY
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lies: one genus has a meiotic division, the other two have not. To add<br />
further confusion, evidence is emerging that the genus Glugea, previously<br />
considered as apansporoblastic, may indeed be pansporoblastic (C a nn<br />
i n g, unpublished results).<br />
In conclusion, Dr. Canning suggested that at this time a reappraisal<br />
of the classification may be justified at ordinal and familial levels<br />
to see whether nuclear cycles can give clearer indications of the<br />
phylogenetic relationships of the genera.<br />
The speaker expressed her gratitude to her colleagues, particularly<br />
to Drs. E. I. Hazard and J. Vavra (the official Discussant), for<br />
discussions from which her ideas were formulated.<br />
(There was little discussion of the Phylum MICROSPORA, beyond<br />
the remarks made by Dr. Vavra. Evidently, only relatively few<br />
groups of protozoologists are well acquainted with this unique protozoan<br />
group.)<br />
Phylum MYXOZOA<br />
Speaker<br />
Dr. J. Lom (Czechoslovakia)<br />
Discussant<br />
Dr. L. Mitchell (U.S.A.)<br />
Dr. LOM remarked briefly about the phylum MYXOZOA, which<br />
is unfamiliar to many protozoologists:<br />
1. The phylum is clearly distinct from all the other protozoan groups.<br />
Paramyxidae can no longer be considered as related to MYXOZOA (see<br />
Desportes and Lom 1981);<br />
2. Several characters have been used in support of the relationship<br />
between the myxozoans and coelenterates. These included similarities<br />
between larval development of narcomedusae and the myxozoans, the<br />
existence of parasitic coelenterates, and the close resemblance of morphogenesis<br />
of the polar capsules and of the coelenterate nematocysts. Of<br />
these, the last feature is the most important; it can hardly represent<br />
convergence. It seems that either Coelenterata originated from MYXO-<br />
ZOA or might have undergone parallel evolution;<br />
3. The present-day classification of the class MYXOSPOREA is artificial,<br />
being based primarily on the spore structure. Shulman's<br />
classification (1966), useful in diagnoses, should, however, be retained<br />
for practical reasons. Until more natural criteria can be established, only<br />
relatively small modifications, including the elimination of the family<br />
Myxosomatidae, ought to be introduced into this scheme. The natural<br />
criteria should be sought among the life-cycle stages (e.g., origin of the<br />
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