I checked Amphibiaweb, and it too seems to be not thoroughly updated and does not add any more information, I'm afraid. According to Amphibiaweb, Hylomantis lemur is now Agalychnis lemur. When looking at the Agalychnis article, it only contains 6 species including Agalychnis lemur, but not the other Pachymedusa or Hylomantis species. The Agalychnis litodryas is however removed.
When looking at Hylomantis article, it lists all the species that is/was in the genus, and I can't find anything about it being merged with Agalychnis.

I might email the people suggested, if no-one can explain how it really is.