RANCHERA, basically a waltz, polka, or bolero, concerns itself with love, patriotism, and nature. SON is a fusion of indigenous, Spanish, and African musics, much like Cuban son ~ but it varies from region to region. MARIACHI is both a genre and a band (composed of 2 violins, 2 trumpets, a Spanish guitar, 2 other guitars called vilhuela and guitarron, and today, trumpets.
The quijada (jawbone of a donkey or burro) is a great "guiro-type" percussion instrument. It's a rather large jawbone, fully-toothed. The variety of sounds a Quijada player can get is pretty thrilling (to me, anyway).