Here's some pics of some of my favorite "dark" colored daylilies.
VICTORIAN GARDEN STAR BRIGHT is one of my all time favorites
and one of the darkest daylilies I grow. It holds up very well in the sun and looks about as good at the end of the day as it did in the beginning.
John Benz NIGHT FLYER is probably the darkest that I grow. This year I measured scapes that were 45" tall
CREATURE OF THE NIGHT is another dark
RAVEN WOODSONG
BOOTY CALL by Curt Hanson is also pretty dark