There is no website that lists a dichotomous key or describes Pandinus genus. There are a couple of papers that describe a number of Scorpionidae.
Recognition and distribution of the scorpions of the genus Pandinus Thorell, 1876 accorded protection by the Washington convention
authors: LOURENCO W. R., CLOUDSLEY-THOMPSON J. L.
journal: Biogeographica vol 72
I haven't made the time to read it yet myself, so maybe you could give us a review?