Two species of Ideopsis are known from Vietnam: Ideopsis vulgaris and Ideopsis similis.
Both species look very similar and they can also be easily confused with Parantica agleoides and Parantica aglea.
The shape and arrangement of the markings on the wings between the Ideopsis species and Parantica species are a little different.
The shape of certain white spots on the underside of the wings determines whether it is Ideopsis vulgaris or Ideopsis similis.

1st, 2nd & 3rd photo: Cat Ba National Park, Cat Ba Island, Vietnam, 6 January 2024
4th & 5th photo: Ben Tre area, Mekong Delta, Vietnam, 23 December 2023