Complications arise because the lines between strains has been severly blurred. Over years of cultivation i doubt their is a "pure" sative or "pure" indica. This completely blends the boundries of their individual species. But taxonomy is subjective and is an interpritive science.

Ruderalis is smaller then indica and sative it does share similar stages and is much more durable. It is just two abstract for me, personally, to see it as a subspecies of sative. Sub species should be like Blueberry, skunk, S.A.G.E. so on and fourth. While ruderalis is an entire batch of genetics, like all indica strains or sativa strains.

Either way ruderalis shows some great potential for breeding in the future. Both for industrial and recreational purposes.

And on the topic of "rasta" i checked it out on the wiki;

" Cannabis rasta is purported to be a new species discovered by Simon Gilmore of the Canberra Insitute of Technology. Gilmore ran DNA analyses of 196 sample plants by their mitochondria and chloroplasts. He drew these plants from sources grown for drugs and hemp as well as wild specimens from Europe, Asia, Africa, Mexico, and Jamaica.

The study results revealed three distinct "races" of cannabis according to their DNA. Plants from central Asia were predominantly Cannabis indica, while those from western Europe were primarily Cannabis sativa. Samples from south-east Asia, India, Africa, Jamaica and Mexico showed a predominance of the rasta variant. In appearance it is similar to the sativa species, but generally contains higher levels of THC.

Because the study was of DNA rather than a formal taxonomic study, "Cannabis rasta" is not an official species. It appears to be identical to the narrow-leafed drug biotype of Cannabis indica. "