Evidence Of Piercing And Sexual Differences In Venom Composition In A Sexual Stinging Scorpion (Scorpiones: Euscorpiidae)

The males of the Mexican species Megacormus gertschi Diaz-Najera, 1966 (Scorpiones: Euscorpiidae: Megacorminae) sting the female repeatedly in the pedipalp tibia-patella intersegmental membrane (TPIM) during the initiation of the promenade a deux. It has been suggested that the male's venom introduced during this "sexual sting" behavior could generate some sedative effect and reduce the possibility of being cannibalized by the female. However, this is unsupported by evidence regarding venom transference. Mere, we provide evidence of perforation of the TPIM by the male aculeus and venom transfer during sexual sting performance. We also provide the first venom characterization of this species and show that it has a sexually dimorphic composition. These results, in combination with observations that the sexual sting is displayed in successful matings with non-defensive females, lead us to consider the pre-insemination sexual stinging as a non-genitalic sexual interaction with a potential role as a courtship element.