Mazda and Alfa Romeo parent company Fiat have announced the signing of a non-binding Memorandum of Understanding (MoU) for the development and manufacturing of a new convertible sports car for the Alfa Romeo brand based on Mazda’s next-gen MX-5.

Not to be mistaken with the smaller and more exotic Alfa Romeo 4C, which will be built by fellow Fiat subsidiary Maserati in Modena, Italy, the new convertible sports car for Alfa will be built by Mazda alongside the MX-5 at the Japanese automaker’s plant in Hiroshima, Japan.

Production of the new Alfa Romeo is scheduled to start in 2015.

Under the plan, the Mazda and Alfa Romeo models will share a basic rear-wheel drive platform being developed for the next-gen MX-5, which is due out next year as a 2014 model. The two cars will be differentiated by their styling and engines, which will be unique to each model.

The details of the partnership are still being worked on, though a final and binding agreement is expected to be signed in the second half of this year. Importantly, both automakers are open to further opportunities for co-operation.

Speaking at today’s announcement, Fiat CEO Sergio Marchionne said, “This agreement clearly demonstrates our commitment to Alfa Romeo and the determination to grow it into a truly global brand. By partnering with Mazda, we will be co-operating with the recognized leader in compact rear-drive vehicle architectures in order to deliver an exciting and stylish roadster in the Alfa Romeo tradition.”

Mazda boss Takashi Yamanouchi added, “Establishing technology and product development alliances is one of Mazda’s corporate objectives and this announcement with Fiat is an important first step in that direction.”

With Mazda no longer a partner of Ford, the automaker has been actively seeking an alliance with another major firm to share everything from whole platforms to manufacturing facilities, so today’s announcement is not a complete surprise. Furthermore, Alfa Romeo has long been rumored to be working on a new ‘Spider’ and even rolled out the stunning 2uettottanta convertible concept in 2010 hinting at the possibility.