What is the dart frog toxin allegedly used to kill Alexei Navalny?

Russian opposition leader Alexei Navalny was killed using a toxin found in South American dart frogs, according to the UK and European allies. Traces of epibatidine, a neurotoxin 200 times more potent than morphine, were found in Navalny's body, leading to his death in a Siberian penal colony. The Kremlin dismissed the claims as an information campaign. The toxin is extremely rare and only found in specific species of dart frogs in South America.