Mournful Desmia Moth

Definitely a Desmia sp., but as Philip pointed out it is really hard to impossible to separate the several Desmia sp. for sure from only a picture without the native specimen. Personally I would leave this as Desmia sp. and not going down to species level. The first spot looks for me more slim than usual Ploralis show. It might be a candidate, but we can't be 100% sure. http://www.boldsystems.org/index.php/TaxBrowser_Taxonpage?taxid=7475

I'm IDing it as Desmia ploralis, because it looks a bit like it: http://mothphotographersgroup.msstate.edu/species.php?hodges=5167, and I know from bold that it is in Costa Rica. Honestly, that genera is one of the hardest to differentiate by picture, so take that ID with a grain of salt.