Here's an update from the Barovier folks in Italy.
"Both the family Barovier and Toso have designed together this vase."
They were very kind to correspond with me, but this doesn't really answer my question. Inasmuch as Barovier "house designer" Ercole died in 1972 and this piece was produced in 1975, it would be helpful to know who at this important house stepped into that role. I'm skeptical that it was designed "by committee," as the answer suggests.
Anyhow, any information or opinions would be most welcome.
Charles.