One of the brethren, just as curious but more enterprising than me, managed to find some historical documentation of this event in a commemorative volume of Marian items worthy of memory published in 1955 in celebration of the one-hundredth anniversary of the dogmatic definition of the Immaculate Conception. In the book one reads:
…Ministro ac Definitoribus generalibus, Beatissimam Virginem Mariam, quam sub mysterio Immaculatae Conceptionis...in principalem totius Capuccinorum Ordinis patronam ac Protectricem eligere…*
I know it's not a complete sentence, but the book was only in my custody for a few minutes and I didn't have time to transcribe any more than that. But it's enough to see that Mary, under the title of the Immaculate Conception, was 'elected' principal patroness and protectress of the whole of the Capuchin Order by the General Minister and General Definitors. The General Minister in question was (the newly elected) Michelangelo of Ragusa. The book also includes a plate with a reproduction of the respective decree, which, if it was at all legible, I might have thought to try to reproduce for this post.
The text goes on to say something about how a Mass with a proper preface of the Immaculate Conception could be offered in celebration of this 'election.' If I read it right, it was to become an annual commemoration. But, I guess like so many of the ancient liturgical privileges enjoyed by us Franciscans, who knows what happened with that. Such things have either been made moot by rubrical silence and post-modern pluriformity (such as our privilege of offering Mass discalced) or have disappeared (like the invocation of St. Francis in the Confiteor) into the new, blander diversity to which we have become so attached.
So as she has always been united to us in prayer, let us ask again the prayers of Immaculate Mary, that we may have the courage to imitate her own vocation, conceiving the presence of Christ in ourselves, nourishing him, bearing him to the world, and finally accepting the suffering of standing by him crucified and killed by the world for which the living God is a scandal.
Virgin made Church, pray for us
Queen of the Seraphic Order, pray for us
Patroness and Protectress of the Capuchin Order, pray for us
Immaculate Heart of Mary, pray for us
O Mary, conceived without sin, pray for us who have recourse to thee
*Regina Immaculata: Studia a Sodalibus Capuccinis Scripta Occasione Primi Centenarii a Proclamatione Dogmatica Immaculatae Conceptionis B.M.V. Collecta et Edita a P. Melchiore A Pobladura, O.F.M.Cap. (Rome: Institutum Historicum Ord. Fr. Min. Cap., 1955), 296.