(Madera, CA.)  UC Merced Head Cross Country Coach, Spencer Castro, has announced the signing of Madera South High cross country star, Sofia Rios, to a Letter of Intent.  Rios is the second high profile athlete from Madera South to commit to UC Merced, following former Stallions volleyball star and all CIF player, Valeria Martinez, who signed with the Bobcats last year.  Martinez, a freshman, was a First-Team All Cal-Pac Conference player this past season for the Bobcats.