Does the muster roll show any others at Camp Kiamishi? Does it indicate that it is in "C.N." (Choctaw Nation) or otherwise indicate it was in the Indian Territory?
Post war maps show a place on the Texas-side of the Red River, nearly across from the mouth of the Kiamichi River, with a similar name: 1872 Kiomatia.
Do you know where the regiment was located at this time -- Feb '63? That might help to locate the camp. They may have been scouting in the Choctaw Nation.