The spread is attributed to Arturo De Ascanio. He originally called it "El Culebreo" which could translate as "the Wriggle" bringing to mind the snakelike movement of the cards. It was Fred Kaps who named it the Ascanio Spread.
However, Eddy Taytelbaum claims to have originated the move in this quote from an e-mail to Pete Biro which is in the Genii Forum thread linked below:
In regard to the Ascanio spread I can inform you that I devised it in the early fifties and showed it to Fred in the company of Pete Forton and maybe Werner Seitz. That time Fred was working often in Spain and he showed it to Ascanio. I must say that Ascanio added a worthwhile addition to the move for which I want to give him credit. His addition was moving one of the cards in the spread like a snake (colebra). It certainly added to the move. Another guy I showed it to in the fifties was Del Cartier who would always visit me when in Europe.
It is important to note that this claim was raised after both Ascanio and Kaps had died and, as a result, they can't verify or challenge Taytelbaum's claim. Although based on Bill Palmer's post on the Cafe, Piet Forton has collaborated Taytelbaum's claim. But the unanswered question is why Fred Kaps would call it the Ascanio Spread if he was the one that had been shown it by Taytelbaum?
Give a magician an answer, they understand for a day. Teach them how to find the answer, they learn for a lifetime. Check out these links for details and bookmark the sites if you want to research your own answers for future questions:
Magicpedia
Genii Forum
Magic Cafe
Behr Archive
Note the 19th post on the Genii forum thread is by Jon Rachembauer who wrote the 1976 booklet The Ascanio Spread.