I am looking for the significance of Montenegro in the Fonseca Montenegro name and the clue it might provide in further research.

I am looking for the significance of Montenegro in the Fonseca Montenegro name and the clue it might provide in further research. I have traced the Fonsecas from San Diego de Alejandria and Arandas, JALISCO back to Salamanca, GUANAJUATO in 1649 with the child of Joseph De Fonseca Montenegro and Cathalina Ortiz Calderon. This is where I am stumped. The Montenegro name occurs for over a hundred years then disappears. Thanks. Evie