This frog species, ranked as Endangered on the Red List, is known only from the Cordillera El Sira in central Peru between 750 and 1,560 m above the sea level. Even though it was discovered relatively early, this remains one of the most poorly known species of poison frogs. It has been proposed that it was highly tree-dwelling because of its remarkable agility and long limbs with well-deweloped finger discs.
Frogs’ head and back are red or dark red, with individual smaller black dots. The ventral side and limbs can be greyish or bluish and they, too, show some black spots. There is a big yellowish-orange spot on the frogs’ ventral side.
Many consider R. sirensis to be the “holy grail” of poison frogs. Being exceedingly rare, it is surrounded my a veil of mystery and is enigmatic to the point that no one is sure about its evolutionary relationships.