Moths of Victoria (Part 7 supporting disc) provides an illustrated guide with arrows to distiguishig S. chionomera from S. loxographa (page 3/3 for S. chionomera). In both species the lines are less dense in the females. I am assuming this a female because the male have strongly branched attennae. The distiguishing marks given for S. chiomomera are: speckling present; A. obscure grey patch forward of the mid forewing (just visible, I think); and B. dark spot on the outer hindwing main line. These are absent in S. loxographa (see CNM example).