Anurans harbour a rich endocommensal fauna from Protozoa to Acanthocephala, each having a different grade of host-parasite relationships. Among protozoans, the rectal ciliates outnumber all others and constitute a very interesting heterogenous group of organisms that coexist in one and the same environment to the extent that literature on these forms "is as confusing and confused as is the taxonomy of the ciliates themselves" (Corliss, 1978).
There is much information on different species of endocommensal rectal ciliates of anurans from other parts of the world. The present study which was undertaken for a period of two years (1981-1983) was aimed at studying the endocommensal ciliates of anurans of Andhra Pradesh. During the study, besides 6 known species, 13 new species, 2 each of genera Balantidium, Trichodina, Metasicuophora and Prosicuophora; 4 of Nyctotheroides and 6 of Sicuophora were encountered, described and their systematic position discussed. The paper contains keys to the identification of all Indian species and individual descriptions of those forms found in Andhra Pradesh.