Pierre (or P) Ibara (Ibar, Ibera, Yberra, Ybarbo, etc) served in Company B of Wingfield's 3rd LA Cavalry (also the 9th LA Partisan Rangers, an earlier - before Sept. 1864 - designation for this unit). You can find a roster on the Natl. Park Service CWSS (http://www.itd.nps.gov/cwss/soldiers.cfm), where your ancestor is listed as P Ibara, or you could try to Google "Wingfield's 3rd LA Cavalry" and the "9th LA Partisan Rangers."

Hope this helps

Don Parker