Easy shit. Son del Pedregal. The bassline is not what I would usually play on harp for a piece from Michoacan, but I assume the guitarron player will play something like this. I'll have to wait to see what the full group arrangement looks like. I'm frankly shocked that this is in a Michoacan section, it sounds a lot more like an old school Jalisciense to me
Playing harp in a mariachi is weird because there are so few of us, which means that arrangers, composers, transcribers often don't know how to write music for us and we end up just working things out by ear and transcribing our own stuff (or in the cases of folklorico shows, transcribing a recording from a cd or (worst case scenario) a cellphone recording of what the group 8 years ago that sounds like it was recorded with a potato)
(Yes, instead of "transcribed by" or "transcriber" I just write "trans" and yes instead of my name I just use BlueEarOtter on all my music)