There is no such thing as a "TACA Regional Airlines", per se, inasmuch as a motley grouping of domestic airlines in each country.
Aeroperlas on Panama
SANSA in Costa Rica
La Costeņa in Nicaragua
Isleņa in Honduras.
They provide feeding to TACA and paint their airplanes with the blue tails and the characteristic red splotch (I believe it's blood from a birdstrike with a some poor guacamayo somewhere over the Central American jungles).
Most of them pay very poor wages and the treatment from management, I've been told, is deplorable. The only reason for being there is 1) you cannot work in the USA or other country, or 2) you are low-time and hoping to get into TACA (plus reason 1).