Abstract
A new species of Elachistocleis (E. magnus) is described from the Amazon basin, in the municipality of Espigão do Oeste, state of Rondônia, Brazil. It differs from all other species of the genus by the combination of the following characters: i) size larger than 31 mm in adult males, ii) grayish ventral coloration, iii) presence of large post-commissural glands, iv) lack of red coloration in the body, and v) grayish dorsum in preserved individuals. There is dimorphism between males and females in size, structures and coloration. Vocalizations and larvae remain unknown.References
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