Amanita rhopalopus - Amanitaceae.org - Taxonomy and Morphology of Amanita and Limacella
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name Amanita rhopalopus
name status nomen acceptum
author Bas
english name "American Club-Footed Lepidella"
synonyms
≡A. radicata Peck
=Amanita rhopalopus f. turbinata Bas
non A. radicata Voglino
images


  • 1. Amanita rhopalopus, Preston Co., WV, U.S.



  • 2. Amanita rhopalopus, Preston Co., WV, U.S.


  • 3. Amanita rhopalopus, ca. Blowing Rock, NC, U.S.


  • 4. Amanita rhopalopus, Preston Co., WV, U.S.


  • 5. Amanita rhopalopus, Paynetown St. Recreation Area, Lake Monroe, Monroe Co., Indiana, U.S.A.

    • intro The following is based on the description of Bas (1969) and on material reviewed by RET.  Before settling on an identification of a collection as belonging in A. rhopalopus, the reader should check the possibility of the collection being A. ravenelii, which can sometimes appear deceptively like the present species—as Dr. Bas noted in his monograph on section Lepidella.
    cap

    The cap of A. rhopalopus is (30-) 50 - 180 mm wide, white, with the center sometimes subumbonate, although usually somewhat depressed with age.  This species has a nonsulcate, appendiculate, initially inflected margin that may extend several mm beyond the ends of the gills.  The cap is densely covered with whitish, adnate to subdetersile, subverrucose, floccose-felted or subfelted patches, irregularly shaped, subfloccose warts or, especially at the center, subfloccose, conical warts.

    gills

    The gills are crowded to rather crowded, free to narrowly adnate, moderately broad to rather narrow, thin, and white to pale cream.  The shortest gills are truncate; the remainder of the short gills are attenuate.

    stem

    The stem is about (50-) 120 - 200 × (4-) 10 - 25 mm, subcylindrical or narrowing upward, solid, white, mostly with some inconspicuous to rather distinct, subfloccose-felted warts, scattered or in a few circles at the base of the stem.  The apex of the stem may be floccose from remnants of the annulus that is usual torn early in development and uncommonly leaves an appressed floccose ring near the stem apex.  The basal bulb of the stem is often deeply rooting, mostly enlarged, cylindric to subclavate to fusiform.  A small bulb collected whole measured 70 × 31 mm; however, the bulbs can get much larger than this.  There are false rootlets at the base of the bulb.

    odor/taste

    The odor of this species is strong and pungent of decaying protein.

    spores

    The spores measure (7.3-) 8.0 - 10.9 (-12.5) × (4.8-) 5.4 - 6.8 (-8.1) µm and are amyloid and ellipsoid to elongate.  Small clamps are present at bases of basidia.

    discussion Amanita rhopalopus was originally described from the eastern U.S.  Its range is presently known to extend from New York to Tennessee and North Carolina.  It is found in oak, pine-oak, and beech-oak forests.  It appears to be an upland species in the southern part of its range.

    The present species can be confused with an as yet undescribed taxon that has a largely overlapping distribution—Amanita magniradix Tulloss nom. prov.—that was not known to Dr. Bas in 1969.  The undescribed entity is also white with flocculent volva; however, its stem base is narrower and radicates so deeply that I've never known a specimen to be collected in its entirety.  The annulus of the undescribed species is distinctly less membranous from the outset; and its spores are markedly more narrow on average than in A. rhopalopus.  In my experience, the undescribed species is more common than A. rhopalopus in some regions and is often misdetermined as A. rhopalopus.
    Note: The author of this page would be interested in receiving well-documented, well-dried collections of both of the above taxa.
    Amanita rhopalopus is sometimes confused with A. ravenelii (Berk. & M. A. Curtis) Sacc. of Bas' stirps Ravenelii.  The nature of the two volvas is very distinct.  In the field, a hand lens will quickly reveal the radially oriented nature of grooves and fibers on the warts of A. ravenelii that is illustrated on the page for that species.  The warts of A. rhopalopus are more nearly formless.

    Bas based his stirps Rhopalopus on the present species.  This stirps also was defined as including A. conicobulbosa Cleland (from Australia) and A. smithiana Bas (from western North America).

    My own observations and those of some correspondents indicate that bulb shape is very variable in A. rhopalopus and that A. rhopalopus f. turbinata Bas seems not to have taxonomic significance.  While Bas' spore measurements from three collections for f. turbinata show spores slightly smaller than those of the type form, my measurements from three different collections shows spores slightly larger than those of the type form.  Combining these two sets of data on f. turbinata, the available spore data for f. turbinata is very similar to available data on the spores of the type form.

    Form turbinata was originally described from North Carolina, USA.—R. E. Tulloss
    brief editors RET

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