Studies have been carried out on protozoan parasites of freshwater
fish from the Amazon region of Brazil, and the British Isles. Special
emphasis has been given to aspects of the taxonomy and life - history
of species of the order Myxosporida.
In section 1, full descriptions are given of Myxosporida from
Brazilian and British fish. The Brazilian species include three of the
genus Myxobolus from piranha (Serrasalmus sp, and S. rhombeus) and
tambaqui (Colossoma bidens), and Agarella gracilis
from lungfish
(Lepidosiren paradoxa). In British fish, Myxobolus species are described
from roach (Rutilus rutilus), gudgeon (Gobio gobio) and dace (Leuciscus
leuciscus); Myxidium species are described from roach, gudgeon and
salmon (Salmo salar).
The similarity of the genera Myxobolus and Myxosoma is noted, and
the difficulty of distinguishing them is pointed out. From the result
of histochemical tests for glycogen In spores of selected species, it
is proposed that the two genera should be synonymised as Myxobolus.
Accounts are given of attempts to establish infections of Myxidium
in Myxidium - free roach and salmon. The negative results of these
experiments suggests that myxosporidan spores may need to undergo some
form of further development outside the host before becoming infective
to a new host.
Check - lists are given of species of Myxobolus, Myxidium and,
recently described Myxosoma species.
In section 2, other protozoa, including two species of Microsporida,
one coccidian species, and Rhabdospora thelohani are described and
discussed.