The Latin verb for studying is studere, but a number of descendants look as if they came from studiare. These include the Italian 'studiare', French 'étudier', and the Spanish 'estudiar'.
Was there ever a Latin verb studiare? If yes, was it interchangeable with studere and do we know how it came about? (I could imagine studiare being derived from studium or arising from changes in inflected forms like studeo > studio.) If no, does something else explain the abundant -i- in the descendants?