G'day Moche,
Today they are called Laetacara curviceps.
Sorry this photo is not in focus, and the fish are pale. I was cleaning the tank at the time and fish were a little stressed and lost thier colour.
Female in front and male behind. Best way to differeniate sex is buy looking for a spot at the base of the dorsal fin. Females have a nice sized, dark spot, while males do not.
However, if the LFS has mislabled L. dorsigera as L. curviceps (which happens a lot in the USA) both males and females have the spot at the base of the dorsal fin.