During Pangea, Madagascar and India were one landmass. The species of frogs were homogenous across the landmass. However, after continental drift that began approximately 88 years ago, allopatric speciation occurred to form different species on the two continents.
The dusky salamanders on the two continents that could once reproduce viable offspring 88 years ago, cannot reproduce viably today because they have diverged into two different species now.