A team led by Chris Funk at Colorado State University in Fort Collins gathered and analysed genetic, morphological and acoustic data for 252 Engystomops frogs and 208 Hypsiboas tree frogs from across six Amazonian countries, focusing on Ecuador. The authors found that the two known species of Engystomops in fact encompass between five and seven species. Meanwhile, the two recognized Hypsiboas species represent between six and nine species (one undescribed species pictured).