About Espadarana prosoblepon (Boettger, 1892)
Espadarana prosoblepon, commonly called the emerald glass frog, was assessed by the IUCN in 2020 and listed as Least Concern. This listing is based on the species' wide distribution, large overall population, and low probability of rapid population decline. The emerald glass frog has a lifespan of over 5 years. It is a small, green frog that may occasionally have dark spots on its back. Its body is translucent for camouflage, it has green bones, and both males and females have humeral hooks used for fighting; these hooks are larger in males. This species is native to Colombia, Costa Rica, Ecuador, Honduras, Nicaragua, and Panama. Males are territorial, and males call from leaf branches to attract mates, with the spacing between male territories dependent on their calls. Breeding takes place during the rainy season from May to November. Espadarana prosoblepon is medium-sized: adult males measure 2.1–2.8 cm in snout-to-vent length and weigh approximately 0.11 g, while adult females measure 2.5–3.1 cm. Tadpoles are around 1.2 cm long, with eyes and nostrils positioned on the dorsal side of the head. The species can be distinguished from other glass frogs by the protruding humeral spine in males and the presence of webbing between the third and fourth fingers. While male body size and humeral spine size varies between individuals, these traits do not determine the outcome of aggressive interactions between males. Viewed from above, the head is wide and appears rounded. It has large, protruding eyes set close together, and the tympanum is either absent or not visible. It has vomerine teeth, and its smooth translucent skin makes its bones and intestines visible; the intestines are less visible due to a covering white membrane. Its fingers vary in length (the first finger is longer than the second) and are webbed. Emerald glass frogs live in humid terrestrial and freshwater habitats, including rainforests and wet forests. They have both terrestrial and aquatic life stages, so they typically inhabit vegetation alongside streams. They prefer shallow streams, as these have more rocks and logs with vegetation suitable for egg deposition and experience less flooding than deeper streams. The species' overall range extends from eastern Honduras, through Nicaragua, Costa Rica, and Panama, to the Pacific slopes of Colombia and Ecuador. In Colombia, it occurs in northern and eastern areas along the Cordillera Oriental and the Magdalena Valley, and is also found along both the Caribbean and Pacific slopes. It is frequently recorded across Costa Rica, but has experienced a drastic population decline in Monteverde, Costa Rica since the mid-1980s. Recorded declines in Costa Rica may be caused by chytridiomycosis, though this requires further investigation. Other Costa Rican populations remain stable, and in some locations such as Zarcero, the emerald glass frog is the most common glass frog species in the area. It is common in Panama, Nicaragua, and Ecuador, and reasonably common in Honduras and Colombia. The overall population of the species has a currently stable trend and its range is not considered fragmented. Emerald glass frogs show strong site fidelity, typically staying within a 2-meter home range, though migration may be possible. Studies have found that the activity level of both males and females increases with rainfall. The species' range includes at least one protected area: the Ranita Dorada Amphibian Reserve. Like most frogs, the emerald glass frog is oviparous and has a polygynandrous mating system. Its mating season aligns with the local wet season from May to November, and research has found a positive correlation between rainfall and the number of egg clutches laid.
