The fossil whip spider Electrophrynus mirus Petrunkevitch 1971 (Arachnida: Amblypygi: Electrophrynidae) from the Mexican Chiapas amber (Miocene: ca 15–20 Ma) is redescribed. Its original referral to an extinct family and genus based on an unusual configuration of the pedipalp is shown to be based on a misinterpretation. The family Electrophrynidae has already been synonymized with Phrynidae. Although E. mirus closely resembles modern phrynids, a key diagnostic character relating to the dorsal pattern of spines on the pedipalp patella is not preserved. Since this incomplete fossil cannot be meaningfully compared either to modern genera or to other whip spiders in Neotropical amber, we believe the pragmatic solution is to treat E. mirus as a nomen dubium.