The estimated number of mature individuals is 50.

Russula pleurogena is a small brown species, recognised because of its eccentric stem and habitat. The genus has been extensively surveyed and studied in New Zealand over a period of 60 years and this species not re-found since the original collection in 1981.

A species known only from the type locality, despite extensive surveys locally and nationally, and in an area likely to undergo change due to invasive species and population growth around Auckland city.

Preliminary category: Endangered: D1, MI < 250.

We infer the presence 1 genotypes, x 10 to account for undetected colonies, x 5 to convert to an estimate of 50 mature individuals. Area of Occupancy 4 km2

Russula pleurogena is ectomycrorrhizal with tea-tree (myrtaceae). The only collection had fruitbodies on stems of tree-fern and rotting wood, which is unusual for species of Russula.

The original record dates from 1981 and subsequent surveys of the area have not relocated the species. The location is in an area subject to increasing tourism from the nearby Auckland city with consequent increase in disturbance in the immediate areas. This population is also likely to decrease over the next 20 years as the impact of Kauri die-back on the Kauri forest alters the surrounding forest structure. Areas are also likely to be disturbed because of future disease management actions, although the type locality is not currently affected.