A new species of Glassfrog is described from the lowlands of northwestern Ecuador. The species is placed in the genus Centrolene and differs from the genera, Cochranella and Hyalinobatrachium, by having humeral spines in males. It differs from congenerics by having a uniformly green dorsal coloration, conspicuous humeral spine, and white iris with clearly defined black reticulations. Detailed cranial and postcranial osteological descriptions are provided, and some of osteological features that seem to be peculiar to centrolenids are discussed. A new suite of traits to characterize Glass-frogs and simplify comparisons among species is proposed.