This is an original cover illustration with artist uncredited. for the SF novel by Joanna Russ, was published by Ace in paperback, reprint ed c. 1976 (see cover for reference) - and I don't believe it got wide distribution at the time.  The  painting is unsigned; proof of publication is on the reverse of the backing: indicating the title and Ace #02269.  It's in mixed media, watercolors, pastels, inks, image 11.75" x 6.5" matted and on board 15" x 10.