For 10 points, name this high priest of Jupiter in Roman religion.
The person in this office was subject to an inordinate number of restrictions, such as being unable to leave the city or oversee any assembled army outside the sacred city boundaries and - like a dictator - not being allowed to ride a horse. Georges Dumézil interpreted this person's title as deriving from a god of oaths named Dius Fidius. This person was required to resign upon the death of his wife, whom he married under strict confarreatio and had to be a virgin. This was the most prominent person required to wear an (*) apex at all times when appearing in public. Clippings of this person's hair and nails had to be buried under a felix arbor, such as the oak dedicated to the god this person served. This person was second only to the rex sacrificulus or rex sacrorum at any seated banquet. For 10 points, name this high priest of Jupiter in Roman religion.
The person in this office was subject to an inordinate number of restrictions, such as being unable to leave the city or oversee any assembled army outside the sacred city boundaries and - like a dictator - not being allowed to ride a horse.
Flamen Dialis [prompt on less specific answers like flamen or priest or high priest of Jupiter, etc.]