The specific name, simonyi, honors Viennese naturalist Oskar Simony (1852–1915),[3] who collected the three individuals used to describe the species on Roque Chico de Salmor, in 1889.

Mitochondrial DNA studies suggest that the two subspecies separated recently, due to rising sea levels at the end of the Pleistocene.

[5] Judging from subfossil remains, Simony's giant lizard was much larger before the Guanches colonized El Hierro at the end of the first millennium BC, with some individuals estimated to have surpassed one meter in total length.

[5] Adults are black colored, with lighter legs and tail, and some light spots over the lips and the temporal region.

[4] The extinct nominate subspecies was slightly larger than the one from the mainland, even when the latter is raised in captivity without the action of predators.