I wish I could help more on this one. The James Pendarvis who moved to Alachua Co., FL in 1859 is the father of Harmon Pendarvis. Harmon can be found living in the same household in the Colleton Co., SC 1850 census and is mentioned as James' son in the David Gavin Journal. The Gavin journal also mentions a "falling out" between James and Harmon in ca 1855. I don't know how permanent the "falling out" was, but obviously Harmon didn't make the trek to Florida, as he appears in the 1860 and later censuses for Colleton.
As for James' parentage, I've found nothing to indicate who they may have been, though I suspect John and Elizabeth Pendarvis who were the parents of John Enoch Pendarvis, Lewis M. Pendarvis, Mary Pendarvis Salisbury, and Dorcas Pendarvis Way.