This large weevil has a dark exoskeleton, covered in small hair-like coppery-brown scales. On the sides and posterior, the colouration is lighter with a prominent white streak along the centre of its thorax. It has obvious prominences on its sides and posterior. Its
rostrum is as long as its thorax with a wide channel in the centre. Including the rostrum, its size ranges from 23 to 27 mm. The ngaio weevil was discovered in 1916 by A.C. O'Connor on
Stephens Island.
Thomas Broun described it in 1921 as
Phaeophanus oconnori after its collector. The weevils were observed at the time to be 'feeding on tall fescue and the leaves of trees'. When this species was moved into the genus
Anagotus Sharp, 1882, there were then two species with the name
Anagotus oconnori so the ngaio weevil was renamed
A. stephenensis. ==Distribution==