Apistogramma kullanderi. Top male, bottom female. Photos from article
The largest discovered Apistogramma has been officially described in the journal Ichthiological Exploration of Freshwaters. The authors Henrique R. Varella and Mark H. Sabaj Pérez have named the giant dwarf Apistogramma kullanderi. The new species was originally given the informal name of Apistogramma "gigas" when it was first seen in 2009.
The entire article can be found in pdf format on the Pfeil-Verlag.de website. Most notably Apistogramma kullanderi can grow to over 3 inches in the wild. Mature males and females are have different coloration as seen above. The species can be found in the Curuá River of north central Brazil. Hopefully this species will be making its way into the hobby soon.