From Rocklopedia Fakebandica
Uncle Sam Quarterly #2 (Winter 1941). Freaked out by his hideously powerful and oversized new hands, he kills a nurse, runs off to the jungles of South America and discovers he can play a local violin-like instrument in a way that makes the local apes do his bidding. Superhero and embodiment of America, Uncle Sam, takes him down.
Malvolo's first name is never given.