Amanita nigrescens : Blackening Amanita

Technical description (t.b.d.)

BRIEF DESCRIPTION

Permission to quote extensively from his description of this species was granted by Dr. Geoffrey Ridley (1991).

Amanita nigrescens has a cap that is 25 – 62 (-90) mm wide and convex to plano-convex (sometimes with central depression). Its colors range from very dark brown in the center to dark grayish sepia at the margin. In addition there are dark radially arrange fibrils. The cap is viscid when young or wet. The margin of the cap can be striate for 12 – 26% of the cap radius. The flesh of the cap is largely white with grayish sepia tint below the cap’s skin in the cap’s center. The volva on the cap is dark mouse gray to nearly black and is divided into floccose to smooth patches and large “squarish warts or crumbs aggregated” in the cap’s center.

The gills of this species are free to adnexed, crowded, and pale mouse gray near the edge fading to white near their attachment to the cap. The gills are 4 – 9 mm wide. Short gills are rounded-truncate to abruptly truncate.

The stem is 37 – 80 (-94) x 4 – 11 (-16) mm with an abrupt, bulbous base 10 – 18 (-22) mm wide. The stem is whitish buff to buff to very pale grayish sepia with its surface above the annulus decorated by very dark brown scales in bands. Similar scales formed below the annulus are free at their tops. The annulus is membranous, striate above, very dark brown to nearly black, skirt-like at first, and eventually appressed on the stem. The flesh of the hollow stem is white with occasional pale grayish streaks. The volva on the bulb forms a felted, dark mouse gray, sheathing limb.

Odor and taste were not reported for this species.

The spores of this species measure 8 – 13 x 8 – 13 µm and are globose and inamyloid. Clamps are present at bases of basidia.

Amanita nigrescens is found only in New Zealand in association with Nothofagus.

— R. E. Tulloss

Photo courtesy of Dr. Karl Soop, identification by Dr. G. S. Ridley.