Off coloration, alone, I'd say yes, but I don't think there's any way it actually is O. rugiceps, through taxonomy. The granules on the pedipalps aren't nearly as pronounced as I have seen for O. rugiceps' pics (Ref: The Scorpion Files, photo: Dave Gaban, for one). I'd like Skinheaddave's opionion on this guy because I know he keeps the species it is questioned to be. I've seen some of the description before on O. rugiceps and the pedipalps were accordingly, far more granulated and to more of an extreme than your specimen appears to be, and I don't think it's the lighting. *lol*
Well, I was the one who proposed Opisthacanthus in the first place to Bill and said I was leaning towards rugiceps, though I couldn't be sure. While the chela are granulated, the various pictures I've seen show a great deal of variation. In person, the granulation on an Opisthacanthus can better be described as a series of channels ... you really get the impression that the surface has been carved out slightly rather than any noticable protrusions. This would obviously lead to some photographic variation.
Several years ago, I actually had a O. asper in my collection, which I got from Dave Gaban. The specimen in the picture looks almost identical to the one that I had. Not certain of course, but the resemblance is pretty striking.
I wonder what the hybridization rate is among this genus? I think Mat may have some points there regarding ID, but it is all a matter of gradients, not presence/absense. I would be uncomfortable setting any species name to it, really, though I am still leaning towards O.rugiceps. Perhaps you ought to label it only as Opisthacanthus sp.
Interesting to know that you've seen some specimen with such a varying disposition of granules. One thing will stay the same, though...distal granule and terminal granule number array. I'd say we need to find some descriptive papers on them, but I know I haven't been successful so far, and I don't think that just because it is being questioned, I will have any better luck. I'll start a search for it and see what may come up.
On coloration and in light of Dave's having seen specimen with such low protrusion of granules, I'll have to agree that I'll lean towards O. rugiceps. But, as already stated, without the descriptive papers, there really is no way to be 100% positive. Like Dave said, I'd just label it as Opisthacanthus sp. It does have obvious resemblance to O. asper, but it would be one heck of a color morph for that species. Descriptive papers would, at least, be required on one of the two species to determine, at minumum, what it is not.