nrITS sequences of the two proposed taxa
are essentially identical. So are
nrLSU sequences. The latter are treated in the
next block (numbered "II"). I have attached a
picture showing a full alignment of four sequences
from different samples of A. albiceps and
seven sequences from different samples of A.
sp-WI03.nbsp; Use your browser's "View Image"
option to see a full screen display of the
The alignment has the SSU and LSU segments entirely
trimmed away leaving 498 columns in the
alignment. As you will see, not all of the
sequences are the same length. They vary from
492-498 nucleotides long. This is because
there is a variable length "AT" repeat included in
all the sequences. A
repeat of this sort can happen in nature, and it can
happen during the PCR process. It is not
considered a meaningful difference between the
sequences. The repeat occurs between and including
columns 161-175 of the alignment.
On the left of the alignment are the names of the
Little marks on the otherwise gray bars of the
alignment indicate the following four variations in
Coll. 11 has one C in a column of T's. The
difference happens to be from a sample of sp-WI03.
Coll. 252 has one Y (C or T ambiguity) in a column
of T's. The difference happens to be from a
sample of sp-WI03.
Coll. 387 has one R (A or G ambiguity) in a column
of G's. The difference happens to be from a
sample of A. albiceps.
Coll. 422 has one T in a column of C's. The
difference happens to be from a sample of
If I were to draw a distinction it would have to
be based on one variation in each of 4 columns.
The evidence involving ambiguites could (arguably)
be discarded. The sample size is not
gigantic. I would not judge there is
significant support to separate species on the
information I have provided here.
I should note that this is not an unusual
occurrence for nrITS. There are a number of cases
in which species that appear morpologically distinct
are barely or not at all distinct according to the
barcode. One resolution is to say that some species
have albino basidiomes. Another is to say,
"Wait and see what some other genes will
Here is a sidelight to the story. The three
collections from Michigan (lines 1, 2, and 10 in the
figure) were all made by Huafang Su. They have
a mixture of white and gray caps. One cap of
each color was collected by Huafang Su on the same
day at the same site. These collections are
documented on mushroomobserver:
Again, we report on an alignment of sequences drawn
from collections of (a) A. albiceps (determined by
presence of a purely white cap and conformance of the nrITS
collection's nrITS sequence with nrITS sequences
derived from Quebec
material collected by Y. Lamoureux and identified by
him as fitting his concept of
A. albiceps and (b) the wholely or partially
gray-capped material described on the present page as
Again, the following description refers to a figure
alignment (immediately above).
In this case,
the alignment begins with columns 1-15 containing
the penetratrix-type nrLSU prefix
The sequences were trimmed to match the length of the
shortest in the
original set. As a consequence the alignment is
1435 characters long. It should be noted that at
the last 450 or so characters are in a highly
conserved region of the nrLSU gene, and variation in
this region would be expected to be minimal. In
the present case, we report no variation
In fact, the alignment reveals minimal variation
Columns 113-116 include a variable length (3-4
characters) multi-"A" repeat.
Column 593 has a "Y" in row one, with all other rows
having a "T."
Column 599 has a"T" in row two, while all other rows
have a "C."
—R. E. Tulloss
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