María José Cantudo was the actress who was first seen nude on Spanish cinema screens in La trastienda. While researching Grau, it also came to my attention that Cantudo recorded a song called “Desnuda me”, Spanish for “Unrobe me”.
In the part on Spanish horror of the documentary Eurotika!, Jorge Grau is featured on 18:50 [above].
Today, the full movies of these stills are available on YouTube:
From Castle of Blood I was able to find the exact location of the film still in question. The woman who is wearing the translucent crinoline and who bares her perky breasts appears to be Sylvia Sorrente (Elsi in the film).
From Succubus I was unable to track the still. However, I was able to get a wider shot. La Reynaud appears to be stripping for a pianist seen from the rear in the back.