Description of Euplotes eurystomus:
This is a large (100-160 microns long, 40-90 microns wide) ovoid hypotrich. The buccal region is triangular and there is a single anterior peristomial pouch. The margin to the adoral membranelle zone is high and prominent. The adoral membranelle zone is sigmoid and contains 50-65 membranelles. There are 9 frontoventral, 5 transverse and commonly 4 caudal cirri. The dorsal argyrome is typical of the double-eurystomus type with 10 (8-12) dorsolateral kineties. There are 17-25 dorsal cilia in the central kineties. The macronucleus is typically 3-shaped and there is sometimes a definite concave notch which contains the micronucleus.