Uma resposta email de um bom amigo de um outro forum a confirmar o que eu ja sabia.
False map" is a literal translation of "pseudogeographica". The northern map turtle, G. geographica, was the first map turtle described. When Gray realized that there was another species, he named it "pseudogeographica" to indicate that it was similar to, but not the same as, the "true" map turtle. The various other Graptemys species were not described until much later.