Eric:
Oddly enough, found the pattern here but without the rib:
https://books.google.com/books?id=BO...attern&f=false.
Segmentation in the 'original' was done with a brown magic marker it seems. Hard to tell from the photo, but I would hazard a guess that the rib is either D-Rib or more likely a brownish monofilament like chameleon Maxima (15-20#?). Superfloss I imagine would be a decent substitute as well.