Pitcairn Island postmaster Dennis Christian has pleaded guilty to three charges during a trial into rape and underage sex stretching back 40 years, reports say.
Radio New Zealand reported that 49-year-old Dennis Christian, one of seven men facing sex charges and a descendant of Bountymutineer Fletcher Christian, had changed his plea to guilty on three of the four charges he faced.
The fourth charge was dismissed when no evidence was offered, it said.
Seven Pitcairn Island men - half of the island's male population - face 55 charges of rape and underage sex. Some of the charges relate to incidents that took place in the 1960s, the prosecution says.
The seven include Pitcairn mayor Steve Christian, another descendent of Fletcher Christian who led the mutiny on the British ship, the Bounty, in 1789.
Radio New Zealand said Dennis Christian, a cousin of Steve Christian, had admitted indecently assaulting a 12-year-old girl in the early 1980s. It said details of the other two charges on which he pleaded guilty had been suppressed.
Dennis Christian was remanded on bail by judge Russell Johnson, one of three New Zealand judges hearing the case, for sentencing at the end of the hearing.
Pitcairn is the last British territory in the South Pacific and has a population of just 47.
The rocky outcrop, chosen as a hideaway by the Bountymutineers because it is so remote, is a dot in the ocean, with an area of just five square kilometeres, halfway between New Zealand and Panama.
Pitcairn men, and some island women, say they have a tradition of underage sex dating back to when the mutineers who rebelled against Captain William Bligh first landed in 1790. But British law forbids having sex with a girl under 16.
A group of eight Pitcairn women, most now living in New Zealand, began giving evidence last week via video for the prosecution.