This is very interesting, Robby. I haven't seen too many of the Stylothelae in habitat, and haven't explored much in Jalisco, merely crossing the northern tip on my way to Aguascaliente in 2011.
I found what I believe is a form of M. rettigiana when I was in Mexico last April, but it was well within your yellow coloured distribution area for that species. It was interesting in that it had more hooked central spines that the 1 called for in the description, but FitzMaurice tells me that this is not unusual.
I also found what I think is M. guillauminiana, high up in the mountains in Sinaloa near to the border with Durango. I asked FitzMaurice about this as well, and he says that he would probably merge M. guillauminiana into M. jaliscana, but that my plant could very well be what was called M. guillauminiana.
What you have shown us here is that the known distributions may not be as definitive as the books would suggest. Given that plants fruit, and birds eat fruits, I suppose that distances of 100km of so might not be unreasonable. But how does one decide whether such plants as you found are the result of this, or whether the plants long ago had a greater distribution, and climate or other changes have affected this?