THE COMPLEXITIES IN THE CLASSIFICATION OF PROTOZOA: A CHALLENGE TO PARASITOLOGISTS

This paper revisits the controversial issues bedevilling classification of the parasitic protozoa as a result of varying interest by different scientists belonging to protozoology and parasitology axes. In recent years, the availability of a number of molecular markers has made it possible to analyse relationships between protozoa that would not have been possible using morphological characters alone. Three terms are currently widely used: Protozoa, Protoctista, and Protista. However, parasitologists tend to be very conservative and the term Protozoa is now almost universally used by scientist working with those parasitic unicellular organisms that infect humans and domesticated animals. With the creation of 5 kingdoms, status of Protozoa was raised to that of a kingdom, which formerly was a Phylum. Thus, the subordinate groups automatically became Phyla. The increase in the number of parasitic protozoa recorded from humans and the accumulation of knowledge about their biology led to the creation of taxonomic and other groupings at the subgenus and subspecie levels. Corliss (1994) in his scheme has used both traditional and contemporary approaches and has attempted to retain familiar names as far as possible. It is important that any classification should reflect modern thinking about the classification as a whole, while retaining sufficient traditional material so as to permit every reference to information retrieval system