This species is very similar to Mantidactylus melanopleura, which I had seen on my last trip to Madagascar. A distinction is that in this species the white line that starts at the foreleg insertion and moves towards the snout fades out below the eye, whereas in M. melanopleura it continues and reaches the nostril. This is important information that you should immediately memorize.

Here is a list of all the reptiles and frogs I saw on this 2023 trip to Madagascar.

There are a lot of Mantidactylus species, but this seems to meet all the criteria for being another M. opiparis.