We knew it was there just had it under a different name
This one and 3 other species are in the Alabama map turtle complex. They were all Alabama map turtles up until 1992, when they described Graptemys ernsti and G. gibbonsi. So than there were 3, Graptemys pulchra, G. ernsti and G. gibbonsi with G. gibbonsi being found in 2 river systems, the Pascagoula and the Pearl. With reviewing the DNA work done in 1991 and looking at animals from the 2 river systems, they figured out they were 2 different species. G. gibbonsi from the Pascagoula river system and G. pearlensis from the Pearl river system.