Rugor Nass was the chief of the Gungan people and wore the title of Boss. As such, he wore this ceremonial outfit in all of his appearances throughout the movies, mainly in episode 1 but also including during Padmé’s funerals in episode 3 despite he was no more boss of the gungans. His successor, Boss Leonie would later wear the same outfit during the events of the Clone Wars.
We can note in particular the long coat with golden typical symbols from Otoh Gunga is closed with gold jewellery matching his necklace. Boss Nass also wears the crown associated to his rank as well as military authority cauldrons. Finally, its gungan sandals let appear a complex pattern on his skin, and that he only has three toes per feet while having 4 fingers per hand. Figurines depict him with a ceremonial staff too.