Knotted monofilament (body) Tyer's choice, to match the natural (12 knots of 20 lb mono for a size 20 (the original uses 14 knots of 15 lb Amnesia for a size 16))
CDC (hackle/legs) Olive dun cdc (One feather, wrapped as a soft hackle)
Rabbit dubbing (collar) Black dubbing (A small pinch)
How to tie it
Tie a series of overhand knots along a length of mono, 12 knots in 20 lb mono for a size 20 (14 knots of 15 lb Amnesia for the original size 16), so the knots read as segmentation.
Slide the 2mm black tungsten bead onto the hook and seat it behind the eye.
Start the black thread behind the bead and wrap a base back to the start of the bend.
Tie the knotted mono in at the rear, bind it along the top of the shank, and wrap the thread forward over it to just behind the bead so the knotted segments show as the body.
Tie in a CDC feather by the tip behind the bead and take a couple of wraps as a soft hackle, stroking the fibers back so they sweep over the body; tie off and trim.
Dub a short black rabbit collar over the CDC tie-in, filling the gap to the bead.