A new species of poison dart frog the size of a fingernail has been discovered in Donoso, Panama.

Andinobates geminisae is bright orange and has a unique call. It was identified by researchers from the Smithsonian Tropical Research Institute, the Universidad Autónoma de Chiriquí in Panama and the Universidad de los Andes in Colombia.

According to National Geographic, the species measures just 12.7mm and is still considered something of a mystery.

Study co-author Andrew Crawford said Andinobates geminisae looks nothing like its closest relative because of its electric orange colouring. He said the species may have been confused with a strawberry poison dart frog (Oophaga pumilio) in the past.

He also noted that its bright colour could be a defence system known as "Mullerian mimicry". This is where two or more poisonous species adopt the same colour warning system so predators are more likely to avoid them: "But this is pure speculation at this point," he said, however.

Published in Zootaxa, researchers first found the species in the Rio Cano area in 2011.

Cesar Jaramillo, Smithsonian herpetologist, said: "They've known it was there for several years. However, they were not sure if it was only a variety of another poison dart frog species, Oophaga pumilio, which exhibits tremendous colour variation. Based on morphological characteristics of the adult and the tadpole, I thought it might be a new species of Andinobates."

After studying the species, they found it was unique: "This new species differs from all other members of the group by having uniformly orange smooth skin over the entire body and a distinctive male advertisement call," the team wrote.

It has only been found in a very small area of Donoso, raising concerns about habitat loss and people collecting them for the exotic pet trade.

To prevent its extinction, researchers have recommended the formation of special conservation plans to protect it. It will also be included in the captive breeding programme of the Panama Amphibian Rescue and Conservation project.