What is "pehtwine"

Pehtwine ("Friend of the Picts"; d. 776 × 777) was an 8th-century English Bishop of Whithorn. The Anglo-Saxon Chronicle records his consecration as bishop at a place called Ælfetee; the consecration was perhaps conducted by Egbert, Archbishop of York. The same source(s) inform us that he died in either 776 or 777, on the "thirteenth before the Kalends of October", i.e. on September 19; it also says he was bishop for fourteen winters.