I'm finding it hard to believe that Guinea has over 600 species, when none of its neighbours has more than 100. Maybe it was supposed to be Papua New Guinea.
I don't doubt your good faith, but I'm pretty sure your source is wrong. You can see the species richness dot plot chart in this pdf: https://www.sanbi.org/wp-content/uploads/2018/04/tolley-et-al-2016-african-reptile-conservation.pdf
Guinea seems to have about the same number of reptile species as Ivory Coast, i.e. well under 100. I can't find anything else on the Internet to back up your source.
(my best guess is that they've scanned another database for the word "Guinea", and added together all the species that appear for Papua New Guinea, Guinea, and Equatorial Guinea)
- Republic of the Congo (352)
- Philippines (350)
- Myanmar (337)
- Iran (332)
Guinea seems to have about the same number of reptile species as Ivory Coast, i.e. well under 100. I can't find anything else on the Internet to back up your source.