Lethal grip for an endangered endemic frog: The freshwater crab Potamon karpathos (Decapoda, Potamidae) preys on Karpathos water frog Pelophylax cerigensis (Anura, Ranidae)

Abstract

Invertebrate predation on amphibians is widespread, although unreported in Europe. Here, we present documented predation of the Karpathos water frog (Pelophylax cerigensis) by the crab Potamon karpathos. Pelophylax cerigensis is an endangered, endemic species exclusively found on the Rhodes and Karpathos Islands in the South Aegean Sea, Greece. The Karpathos population is at risk due to limited suitable habitats and a scarcity of freshwater bodies on the island. From April to October, when there is no rain on the island, frogs and crabs cohabitate, sharing the same shallow ditches. Incidents of frog predation by crabs are common, indicated by numerous individuals with amputated limbs and scars, representing an additional threat to the endangered frog. Further research on the interactions between the two species is urgently required, as it has direct conservation implications.