extracted from the topic about Paratheraps/Vieja:
there is no such thing as umbrella genera or whatever. the gender of a genus is set by the original describer, either explicitly (common use nowadays) or implicitly. as such it has nothing to do with the species (to be) assigned to it. sometimes, the meaning of the name can be used to deduct the gender of the genus so called. or the gender can be derived from (the ending of) species names assigned to the genus. when Swainson proposed the name Cichlasoma in 1839 (as a subgenus to Plesiops) he assigned Labrus puncatatus to his new genus. that species ended up as Cichlasoma bimaculatum (Regan 1905). see the complete story in Cichlid News (October 2000).
for your information, a list of the Central American genera and their gender:
masculine: Amphilophus, Archoncentrus, Astatheros, Chuco, Hypsophrys, Nandopsis, Neetroplus, Parachromis, Paratheraps, Theraps, Thorichthys
feminine: Petenia, Vieja