Trust project co-ordinator and pest-control contractor Pete Mitchell said the skink lived in rough, rocky terrain which probably helped protect it from predators and contributed to it not being discovered earlier.
"We have six or possibly seven species of lizard present at Bream Head (Te Whara), which is outstanding for one mainland site, and to now discover something new is unbelievable," Mr Mitchell said.
Ngatiwai Trust Board Resource Management Unit manager Clive Stone said skinks were a taonga to the iwi.
"To Ngatiwai, indigenous fauna are whanau and taonga, to be looked after for future generations. They are kaitiaki of their habitats and to some of our people they are indicators of the health of their surrounding environment and provide signs of events to come."
The BHCT, working with Ngatiwai Trust Board and Department of Conservation, carries out predator control to help native species at Bream Head.
For the past three years its work has been financially supported through a good-neighbour relationship with Refining NZ which has recently agreed to back the trust for another three years.