Based on rRNA phylogeny, morphologic and morphogenetic characters, two major groups of hypotrich ciliates can be distinguished: euhypotrichs and pseudohypotrichs. Through the sequencing of actin genes, we show here that, interestingly, the pseudohypotrichs Dyophrys sp. and Euplotes vannus have a different stop codon usage. In fact, the stop codon usage of the former species resembles that of euhypotrichs. This unexpected result is used to discuss the origin and acquisition of genetic code deviations in ciliates.