My friend Peter Hall sent me a scan from the book by Jon Clifton, where they are to see the differences in males. The males of the species E. cirsiana have one colour, dark hind wings, while the species E. scutulana have a male pale hind wings. In females are the hind wings in both species of one colour-dark, so this character cannot be used.
Maybe this character could use also on the website Lepiforum.
greets František from Slovakia.