“…Neotropical mayflies occupy the Neotropical region and the wet portion of the South American Transition Zone (STZ). An essential portion of the STZ (the southernmost) overlaps with an arid stripe, the Arid Diagonal (Bruniard, 1982), that would be acting as a barrier for (Nieto, 2016) Baetodes huaico UC 11 Marginal Monte NT, NC (Nieto, 2016) Baetodes levis UC 7 Marginal Paramo NT, NC (Nieto, 2016) Baetodes pehuenche UC 13 Endemic Monte NT, NC (Nieto, 2016) Baetodes spinae UC 7 Marginal Paramo NT, NC (Nieto, 2016) Baetodes traverae UC 2 Endemic Desert NT, NC (Nieto, 2016) Caenis dominguezi UC11 Marginal Monte NT (Malzacher, 2001) Caenis gonseri UC13 Marginal Monte NT (Malzacher, 2001) Caenis ludicra UC11 Marginal Puna NT (Malzacher, 2001) Callibaetis jocosus UC8 Marginal Cuyan High Andean NT (Cruz, Salles, & Hamada, 2017) Camelobaetidius edmundsi (Pescador & Peters, 1986) Mayobaetis ellenae UC 12 Marginal Paramo NT, NC (Nieto, 2016) Meridialaris laminata UC 13 Marginal Monte P (Pescador & Peters, 1986) Meridialaris tintinnabula UC 11 Marginal Monte P (Pescador & Peters, 1986) Nanomis galera UC 12 Marginal Puna NT (Nieto, 2010) Prebaetodes sitesi UC 7 Marginal Paramo NT, NC (Nieto, 2016) Thraulodes trijunctus et al, 1998). This massif is one of the various small Precambrian cratons constituting the South American platform, actually including the Pampean mountain ranges in NW Argentina.…”