I found some older discussion of these two species on Butterfly Circle, but it did not seems to come to any conclusions on good features to separate these two confusing species. I attach a number of images, of which the three from Nan and Phrae provinces I have tentatively identified as aliris but would be interested in some feedback on how to separate these.
Image 1, from se Thailand, should be T. laythi, due to predominantly reddish tinge, and aliris being unrecorded from se Thailand.
Image 2. Is assumed T. laythi from Doi Suthep.
Image 3, 4 and 5 are assumed T. aliris, based purely on them not being very bright, but does wear affect this? Interested in feedback on any morphological differences. Many thanks
Thanks for the interesting feedback. Interestingly, there are no collected specimens mentioned in Yutaka or Kimura for aliris from se Thailand, whereas image 1 from Khao Soi Dao is from se Thailand, but indeed looks like aliris. Very confusing.