It's correct what Andrew stated.
Since the last revision done by Faivovich et al. in 2009/2010 there has been some changes in the Phyllomedusinae.
I won't go to deep into detail, since it's rather difficult material, especially to discuss in a foreign language
The genus Agalychnis so far consists of 14 species (according to Faivovich et al.) , namely:
Agalychnis annae (Duellman, 1963)
Agalychnis aspera (Peters, 1873)
Agalychnis buckleyi (Boulenger, 1882)
Agalychnis callidryas (Cope, 1862)
Agalychnis dacnicolor (Cope, 1864)
Agalychnis danieli (Ruiz-Carranza, Hernández-Camacho, and Rueda-Almonacid, 1988)
Agalychnis granulosa (Cruz, 1989)
Agalychnis hulli (Duellman and Mendelson, 1995)
Agalychnis lemur (Boulenger, 1882)
Agalychnis medinae (Funkhouser, 1962)
Agalychnis moreletii (Duméril, 1853)
Agalychnis psilopygion (Cannatella, 1980)
Agalychnis saltator Taylor, 1955
Agalychnis spurrelli Boulenger, 1913
The Agalychnis litodryas is found to be synonym to spurelli based upon DNA research.
Main reason for new revision is that the recently surrected Hylomantis proven to be paraphylic with members being synonym for Agalychnis,
by revising these species we get a better evolutionary taxonomy, called cladistics.
Here some info on what this means, why explain if it's already done better then i can do it
Cladistics - Wikipedia, the free encyclopedia
Paraphyly - Wikipedia, the free encyclopedia
Monophyly - Wikipedia, the free encyclopedia
It's true that some things may get difficult by all the revisions.
For example the lemur has switched between originally belonging to Agalychnis and Phyllomedusa quit some times,
in 2005 they were placed in the newly surrected genus of Hylomantis.
Now after new research there is descided to place them back in the genus of Agalychnis.
Most likely in the near future some more changes will follow, since they didn't have access to DNA of all members from the subfamily of Phyllomedusinae.
They only had access to 45 of the 60 species of phyllomedusines.
I must have the papers around here somewhere.
Not sure if i may just upload it, but i might mail it to you so you can read the complete supportive papers going with this hypothesis.
Strange but true, the name changes are only vallid as other researchers and such are convinced by the validity of the research findings and take on the revision or cite in their own publications.