One lobe on the frog's thumb spike (clearly visible from underneath), distinguishes this species from some other candidates, such as Plectrohyla guatemalensis. The yellow flanks with darker spots are also a clue.

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

I didn't check the number of lobes on this frog's thumb spike, but I'm assuming it is the same species I saw nearby the previous night.