I like the name Martita better than just Marta, which is over-used, possibly old, and plainer. Martita has some more spunk, though I wouldn't name a child Martita... a little too flamboyant?
Martita Edith Hunt was an Argentine-born English theatre and film actress. She had a dominant stage presence and played a wide range of powerful characters. She is best-remembered for her performance as Miss Havisham in David Lean's Great Expectations.