Cortinarius viridipileatus is a species of viscid green agaric fungus in the family "Cortinariaceae." It is endemic to Aotearoa New Zealand.
Taxonomy.
It was first described by Egon Horak and A.E. Wood in 1990 as part of the study of "Cortinarius" subgenus "Myxacium" and "Paramyxacium" in Australasia. Initially placed within subgenus "Myxacium" due to its viscid pileus and stipe, later described in 2021 by Xinyue Wang, Mia C. Te Tana, Andy R Nilsen and David A Orlovich supported its placement in section "Delibuti" of "Cortinarius." The holotype specimen was collected on 15 May 2014 at New Zealand: Tasman, Brown River, Heaphy Track, on soil under mixed Nothofagus, Kunzea, Podocarp and Broadleaf, leg. A. Hoeyer.
Description.
The pileus of "Cortinarius viridipileatus" ranges from 30–80 mm in diameter, initially hemispherical, becoming convex to almost plane, distinctly dark green to olive-green, occasionally with yellow-brown patches, even with pale mottling. Surface glutinous when fresh, smooth to slightly fibrillose as it dries, paler green, incurved, entire margin. Context in white colour with green hue occasionally. The lamellae are adnate to emarginate, crowded, initially mauve to lilac, becoming rusty brown as spores mature. The stipe is 35–90 mm tall and 10–15 mm wide, slender, fibrillose, cylindrical to slightly clavate, base often bulbous, white to very pale purple, may have universal veil remnants near the apex. The cortina is yellow-brown. Spore print is rust-brown. Basidiospores globular to subglobose, verrucose (warted). The cap surface tissue reacts to the application of the chemical solution KOH, with no reaction elsewhere.
Habitat and distribution.
"Cortinarius viridipileatus" is strictly mycorrhizal with "Nothofagus" species and can also be found on the beech forest floor under a mix of "Nothofagus and Kunzea" species during the autumn months. The distribution is limited to New Zealand in the central North Island and the upper north, lower south of the South Island.
Etymology.
The specific epithet "viridipileatus" derives from the Latin "viridis" meaning green, and "pileatus", meaning capped or having a cap, referring to its distinctive green glutinous pileus.