The dark one had recently been acquired when I was there as a Western Giant Forest Hog, and it was kept company by this Red River Hog. It is still alive and listed on ISIS as such but some doubt that it is actually that species. See Ituri's comment below for more.
That pig is the subject of much debate. The zoo acquired her thinking she was a western giant forest hog. As she has grown that became doubtful, and DNA tests seem to further that doubt. I think that she is probably a melanistic bush pig.