Signature feature 1
shape. It's been argued for years that River Road alterna
less flattened heads than the more triangular, wider head shapes found
in the eastern populations. Though thoroughly anecdotal, I would have
to agree to the head differences having examined hundreds of
Signature feature 2
pattern. Although other localities do produce animals with speckling on
this feature turns up with the highest frequency in the River Road
population with Black Gaps coming in a very close second. Black Gap
speckling differs in that the speckling is usually surrounded, and even interfered with, the white pigment "halo" effect—see Black Gap Signature Features for more on this phenomena.
Signature feature 3
alternates. Again, other populations can and do exhibit this feature but the
River Road animals set the standard with gene flow again appearing to
|Signature feature 4
shaped primaries. Beautiful, symmetrical diamond shaped primaries are
quite common here and, some would argue, diagnostic. They seem to occur
with about the same frequency as the bat wing (also called bow tie,
hourglasse, butterfly, etc.) primaries occur in the Black Gap
population and are perhaps analogous. Alterna collected near Lajitas are notable for diamond shaped primaries
but this is probably the result of a collecting bias caused by so few animals having
ever been collected near Lajitas.
Signature feature 5
orange. This is a "splitting of the fine hairs" for many, but in most
discussions amongst hardcore alterna fans regarding the quality of
the primary orange in different alterna localities it regularly comes
up that River
Road alterna have a different quality of orange. Though the tone of the
orange can certainly range, the locality is most notable for a soft,
almost pastel orange that is quite unique and beautiful. Somewhat less
River Road examples have a unique "orange"
that is more of a tomato red, reminiscent of L. pryomelana base/background
Signature feature 6
gray. River Road gray can range from ultra light platinum to very
nearly black with
variations of the gray being very common, even amongst littermates.
There is a shade of gray that is common and fairly
unique to this area that we have anecdotally termed, "mineral gray."
is very much like the color of the gray mudstone and volcanic ash found
throughout the Big Bend area. A similarly toned, but slightly different
occurs frequently in alterna from the Davis Mountains. I have noted
over the years that River Road alterna with this mineral gray tend to
also develop orange infusion in the gray once they reach adulthood. The
infusion tends to intensify as the animals age. Some older individuals
can appear almost entirely orange or orange-brown. In the early
collecting days on the River Road we referred to such brownish and
orange toned animals as "buckskins."
Signature feature 7
pin banding and/or high band count. The River Road population can
produce a pattern variant with very narrow primaries and alternates.
These narrow pattern variants usually have very high band/alternate
counts as well. Some examples seem to have a "blizzard" of bands with
banding so dense that the differences between primaries and alternates
becomes obscured. This pattern seems to be unique to the River Road.
Not to be
confused with high speckling.
|Signature feature 8
average size. This is another debatable feature based solely on
anecdotal observations. In general, River Road alterna seem to not
quite reach the adult sizes obtained by their more eastern brethren. This
seems to be especially apparent with wild collected snakes. Though certainly
not dainty snakes by any means, the River Roads don't seem to reach the bruiser
proportions of alterna encountered from eastern areas such as the Devil's River
drainage. Some have proposed that diet (more rodents in the eastern forms) and general sparsity of prey play a roll
in this size discrepancy. My own observations indicate that the size differences can be seen under captive conditions as well.