Her Wikipedia article is here. She had a daughter, Holy Roman Empress Eleonora.
From Wikimedia.
What a headdress! The dress is also unusual for open sleeves that are not virago sleeves and its rectangular collar. She wears a black surcoat in Spanish style. This may be a mourning dress. The wires supporting her headdress form graceful arcs.
Keywords: Maria Gonzaga (1609-1660), Duchess of Mantua, principessa di Mantova, duchessa di Mantova, Princess, Duchess, Italian, frizzy coiffure, floating collar, high neckline, under-bodice, square neckline, bodice, neckline ruff-headdress, scoop décolletage, bodice ornament, strap sleeves, girdle, vee waistline, surcoat, three quarter length puffed sleeves, cuffs, over-skirt