There is the Puerto Rican cuatro.... a 10-string guitar.... but this is mostly used for Puerto Rican folkloric music. There are some awesome cuatro players today.... guys like Christian Nieves. You hear this instrument a lot around Christmas time, when a lot of these songs are played. It's more old style.... but wonderful to hear and enjoy. For Latin jazz and/or salsa..... the bass guitar is still the more prominent string instrument. Without a good bass guitar, it's very difficult to have what we here on the island call "salsa gorda", which is basically the salsa from the 60's, 70's and even 80's.... with the old master musicians putting together some awesome rhythms. Bands like Fania All-Stars, El Gran Combo, La Sonora Ponceña, the bands of Willie Rosario, Tommy Olivencia..... man..... those were some monster musicians right there.