Given that (1) previous studies have detected chitin in lorica (a shell-like protective outer covering of ciliates) and cyst walls of various ciliates (including other Euplotes), and (2) CHS gene is detected in all nine species (Fig. 5A), our results provide further evidence that chitin synthesis is an ancestral characteristic of ciliates (Greco et al. 1990; Yang and Fukamizo 2019). This evidence concerns the gene LYST and cyst.