Olive text indicates a specimen that
has not been
thoroughly examined (for example, for microscopic details)
and marks other places in the text
where data is missing or uncertain.
The following material is based on information and images
from the collectors, molecular research of Dr. L. V.
Kudzma and Stephen D. Russell,
and other original research of R. E. Tulloss.
67 mm wide, broadly campanulate to convex, eventually concave,
yellowish or ochraceous tan with pallid zone over inner
ends of marginal striations, darker and browner over
disc, becoming entirely brown with age and drying, shiny
when moist, matte when dry, with
context white, 6 mm
thick at stipe, quite hard in umbo, ;
margin non-appendiculate and
striate (ca. 0.45R); universal veil absent.
free without decurrent line on stipe; white in mass and
in side view, lacking staining or bruising reaction;
214 - 228 × 10 - 12 mm, pale grayish
white or pale brown with pallid ground sometimes
exposed, unchanging when cut or bruised,
narrowing upward, with lower
108± - 150± mm
inserted in substrate; context
hollow or stuffed with cottony material, white;
exannulate; universal veil as saccate
persistent membranous volva, white, 52 - 63 ×
20 - 23 mm.
Odor lacking. Taste not discernible.
...; vascular hyphae common.
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ca. 55 × 14.5 μm, 4-sterigmate, arising from short
uninflated, slightly inflated, or branched elements; clamps
[20/1/1] (7.7-) 9.5 - 11.5 (-13.0) × (6.8-) 9.0 - 11.0
(-12.0) μm (L = 10.3 μm; W = 9.7 μm;
Q = 1.04 - 1.11 (-1.13); Q = 1.07), hyaline, colorles, with
walls thin or rarely up to 0.5 μm thick; apiculus
sublateral; contents guttulate; color in deposit probably
white or whitish.
Solitary. Missouri: In dark loam over rock and red clay
in mixed hardwood-coniferous forest dominated by
Quercus and Carya (commonly Q. stellata
and C. glabra) with sparsely scattered
New Jersey: With Quercus and Fagus grandifolia.
MARYLAND—Harford Co. - Little
Gunpowder Falls Tr. [39.4763° N/ 76.4083° W, 69 m],
8.viii.2018 Ryan Pridgeon s.n. [mushroomobsever
(RET 858-5, nrITS &
nrLSU fragments seq'd.).
MISSOURI—Butler Co. - Poplar
Bluff [36.7124° N/ 90.407° W, 98m], 9.vii.2015 John
McDonough s.n. [mushroomobserver
(RET 696-4, nrITS & nrLSU seq'd.).
St. Louis County - Forest 44 Conservation Area
[38.528° N/ 90.527° W, 191 m], 4.vii.2015
Patrick Henry s.n. [mushroomobserver
(RET 698-3, nrITS & nrLSU seq'd.).
NEW JERSEY—Hunterdon Co. - East Amwell, Sourland Mtns.,
Rileyville Rd., 9.vii.2014 Nina Burghardt s.n. [Tulloss 7-9-14-B]
(RET 628-10, nrITS & nrLSU fragments seq'd.).
Mercer Co. - Hopewell Twp., Ted Stiles Preserve
[40.3294º N/ 74.8807º W, 127 m], 22.vii.2016 Liz Broderick
(RET 739-9, nrLSU seq'd). Washington
Crossing St. Pk. [40.307º N/ 74.8638º W, 57 m],
16.vii.2016 Igor Safanov s.n. [mushroomobserver
(RET 753-6, nrITS & nrLSU seqd.)
PENNSYLVANIA—Carbon Co. - Lehighton,
just W of Ukrainian Homestead, 22.vii.1996 Joseph A.
Lankalis s.n. (RET 323-9, nrITS & nrLSU fragments
Problems with deriving nrDNA gene sequences
for Amanita penetrans.
Derivation of an nrITS sequence from Amanita
penetrans by means of Sanger Process sequencing
alone appears to be difficult. Possibly,
this is due to failure of the rDNA repeat to
homogenize—as has been suggested for other
species of Amanita (e.g., A.
In the case of the present species, the nrLSU
sequence is also difficult to derive. We have
been able to obtain several fragments comprising up
to the last 88 characters of ITS2 (with capability to
differentiate the species moderately well) and 148
to 485 characters of the 5' end of nrLSU (including
been able to replicate derivation of portions (or
nearly all) of a second, more conserved, region
up to 858 characters long.
This region is largely covered by reads using
the following primers (LR5, LR3R, and LR7). We
select the following sequence (with hets/SNPs
as noted) to indicate the 5' end
of the second region:
As might be expected from the relatively high degree
of conservation, the latter fragment is of limited use
for identification purposes (e.g., by BLAST).
However, even in this region, the sequences may
hets within the initial 82 characters; and the
length of derived
sequences have varied greatly—from 335 to 858
Distinguishing Amanita justicei and
A. penetrans with
apparently constant character differences in nrLSU
The nrITS sequences for these two species are
difficult to derive and are confusingly similar and
often contain a number of ambiguities.
We find that there are five features in the nrLSU gene
that, together, distinguish the two taxa. To
find these taxa we created a 2,021 character alignment
comprising all nrITS and nrLSU sequences obtained to
date (9 Nov. 2019) for the either of the two
species. The number of such sequences is
It is important to note that since deriving a
sequence containing the entirety of nrITS has been
possible for us only once in the case of the two
species in question, no comparison could be made for
the first 444 characters of the longest sequence in
the alignment. The nrLSU gene begins
(with "TCTGAACTCAAATCA") at character 533 of the
differences between the two species and related
positioning information in the alignment
T (justicei), G (penetrans)
T (justicei), A (penetrans)
TTT (justicei), TT (penetrans)
C (justicei), T (penetrans)
A (justicei), T (penetrans)
The spore measurements from RET 628-10 should be
considered to be smaller than average because the
specimen cam into my hands about a day after it was
collected and, when collected, it was over mature.
Amanita penetrans is one of the
curious species of section Vaginatae that
yield DNA with the unusual nrLSU 5'
terminal motif TCTGACCTCAAATCA. Other members
of the Vaginatae with this motif are listed on
the techtab of this page: A. penetratrix.
These taxa and others with the motif are
mostly known from Australia and North America at
present; however, we have sequenced material from
India and Madagascar that appear both to belong
to section Vaginatae and to have the unusual
This species was previously called "A.
sp-MO5" in these pages.
—R. E. Tulloss
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4. Amanita penetrans, West Amwell, Sourland Mountains, Hunterdon County, New Jersey, U.S.A.
John McDonough - (1-3) Poplar Bluff, Butler County,
Missouri, U.S.A. (RET 696-4)
[Note: Unedited images in their original
size can be viewed
RET - (4) West Amwell, Sourland Mountains, Hunterdon
County, New Jersey, U.S.A.
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Spore data for collections provisionally identified as: Amanita penetrans Tulloss, Kudzma, S. Russell et al.
Each spore data set is intended to comprise a set of measurements from a single specimen made by a single observer;
and explanations prepared for this site talk about specimen-observer pairs associated with each data set.
Combining more data into a single data set is non-optimal because it obscures observer differences
(which may be valuable for instructional purposes, for example) and may obscure instances in which
a single collection inadvertently contains a mixture of taxa.