Thanks for the info! I'm aware of Santiago de Murcia (am working on learning several of his pieces) and some of the other baroque composers in Latin America (and the CDs you mention). The mystery to me is who were composers for guitar in Latin America after the baroque period, say from 1750 or so, until composers like Ponce and Barrios showed up. The earlier reference in this thread to Vargas y Guzman working in Vera Cruz in the later 1700s is a good example, and there must have been others. Guitar was clearly in wide use in Latin American popular/folk music throughout this period, and there must have been teachers who were writing pieces if not more serious composers--I just haven't found them.
I have a set of albums (vinyl) of Mexican music from the Colonial period purchased years ago in Mexico City. One album is guitar (or lute/vihuela) music, and it does include two pieces (transcribed and played by Miguel Alcazar) by Juan Antonio Vargas y Guzman from his 1776 group of sonatas, but nothing else later than pieces from a 1686 manuscript (including some Corelli).