This MG 614 is an interesting looking plant. But I don't think that it has anything to do with M. schwarzii (although hooked centrals are occasionally present in the latter). The locations, Zimapán, Hidalgo vs. El Cubo near San Felipe, Guanajuato, are more than 200 km apart.
It is a pity that MG 614 is only listed as from Zimapán. That could be a fairly large region. Somewhat southwest of Zimapán is Agua Blanca, and Reppenhagen's Rep. 1697 is from there, just like Fitz Maurice's WAF 2346. Reppenhagen calls that M. crinita var. pauciseta. It still differs much from the Gandolfo MG 614 plant.
However, a bit further southwest of Zimapán, at the Presa Zimapán, is the location of M. scheinvariana, and that plant has some of the looks of the Gandolfo plant.
Fitz Maurice has found M. crinita at several locations around the Presa Zimapán, and it could be that MG 614 is one of his finds, related to M. scheinvariana, but with hooked centrals......
Wolter ten Hoeve.