Powellisetia bilirata

Powellisetia bilirata is a species of marine gastropod mollusc in the family Rissoidae. First described by Winston Ponder in 1965, it is endemic to the waters of New Zealand.

Description
Powellisetia bilirata has a minute shell, with four whorls angled by a strongle spiral chord. The species is pale yellow-brown in colour, with a reddish-brown protoconch. The species measures 1.05mm, by 0.68mm.

Distribution
The species is endemic to New Zealand. The holotype was collected by K. Hipkins on 9 April 1955 from shell sand at McGregors Bay, Whangārei Heads, Northland Region. It is found in to the north-east of the North Island, as far north as Manawatāwhi / Three Kings Islands, and has been found neat the volcanic Whakaari / White Island.