Amanita pachycolea - Amanitaceae.org - Taxonomy and Morphology of Amanita and Limacella
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name Amanita pachycolea
name status nomen acceptum
author Stuntz in Thiers & Ammirati
english name "Stuntz's Great Ringless Amanita"
images
  • Amanita pachycolea, very large button, Camp Gualala, Mendocino Co., California, U.S.A.  (RET 016-7)Amanita pachycolea, very large button, Camp Gualala, Mendocino Co., California, U.S.A.  (RET 016-7)

    1. Amanita pachycolea, very large button, Camp Gualala, Mendocino Co., California, U.S.A.  (RET 016-7)

  • cap

    The cap of A. pachycolea is 70 - 120 mm wide, convex to near campanulate when young, becoming convex to plano-convex to umbonate in age, viscid to subviscid, with a decurved margin (becoming rimose and eroded), conspiculously striate or tuberculate striate (30 - 40% of the radius). The cap is dark brown, carob brown to mummy brown on disc, and becomes paler toward the margin (brown or grayish brown). The flesh is white and 5 - 10 mm thick above the stem. The volva is usually absent or leaves only a few fibrils; it is rarely present as a solitary white to whitish patch.

    gills

    The gills are adnate or decurrent by a short conspicuous hook, usually free in age, close to subdistant or occasionally crowded, white when young, unchanging or becoming tawny to orange-yellow with age, ventricose, and broad. The short gills are truncate to subtruncate, of diverse lengths, plentiful, and unevenly distributed.

    stem

    The stem is 110 - 240 mm long, white to olive buff to sometimes as dark as orange brown, cylindric or narrowing upward, dry, typically with appressed fibrils or fibrillose scaly, and exannulate. The flesh is white, stuffed, and becoming hollow in age. The very large, felted to membranous volva is up to 5 mm thick, white on the inner surface, white to off-white and developing rust colored to brown to yellow-brown spots with age on the outer surface. The volva is up 80 mm from the stem base to the top of its highest limb and collapsing in age.

    spores

    The spores measure (7.8-) 10.0 - 13.5 (-16.5) × (7.5-) 8.8 - 11.8 (-14.0) µm and are globose to subglobose to broadly ellipsoid and inamyloid. Clamps are absent from, or infrequently found on, bases of basidia.

    discussion

    This species occurs from southwestern Canada to central California. Related species with copious volvas and often large fruiting bodies include A. magnivolvata Aalto and A. pachyvolvata (Bon) Krieglst. of Europe and A. violettae Tulloss of eastern North America.—R. E. Tulloss

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