Question about the Enemy List

[Kyanite]

I am missing some enemies on the librarian's enemy list. Shaft and Dracula are the obvious missing enemies, but there is one more. It's below Frozen Half, to the right of Salome, and above Galamoth. I have 200.5% map completion, so I'm thinking that if I find this remaining enemy, I'll unlock the Seeker achievement. Any help is appreciated.

http://www.xbox360achievements.org/forum/album.php?albumid=424&pictureid=2620
Here is my normal castle map.
http://www.xbox360achievements.org/forum/album.php?albumid=424&pictureid=2621

Here is my inverted castle map.
http://www.xbox360achievements.org/forum/album.php?albumid=424&pictureid=2620

Edit: I found the missing room. It's where you find the Ring of Arcana in the inverted castle. No enemies there, but I'm not going to worry about the enemy list. I am mildly curious as to what fills in that blank.
http://www.xbox360achievements.org/forum/album.php?albumid=424&pictureid=2621

[Edward Hyena]

Do you have Richtor Belmont in your Beastiary yet?