Anuroctonus phaiodactylus
(Wood, 1863)
- Today's subject is Anuroctonus phaiodactylus (Wood, 1863). The
generic name, Anuroctonus, is from the Greek word an,
meaning "not,"
and the name Uroctonus, a genus of scorpion from North America. Anuroctonus thus
means "not Uroctonus." The specific name, phaiodactylus,
is from the Greek words phaeo, meaning "dusky," and dactyl,
meaning "finger,"
and refers to the dark coloration of the fingers of the claw.
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Vital Stats:
- SIZE: < 65 mm
- ECOMORPHOTYPE: Fossorial
- VENOM TOXICITY: Low
- DEFENSE: Strikes defensive posture with outstretched pedipalps and forward-oriented
stinger.
- FOOD: Small arthropods.
Systematics:
- This scorpion is in the family Iuridae. Anuroctonus contains
only one species. However, I think we may actually be dealing with a complex
of morphologically indistinguishable species across the range of the genus.
Original Description: Wood, H. C. 1863.
- Descriptions of new species of North American Pedipalpi. Proceedings
of the Academy of Natural Sciences of Philadelphia, 1863: 107-112. This
species was originally described by Wood (1863) as Centrurus phaiodactylus.
The species was later transfered to Uroctonus, before being placed
in Anuroctonus.
Distribution:
- This species occurs in northwestern Baja California in Mexico, and in
southern California, Arizona, southern Nevada, western Utah and southeastern
Idaho in the United States. I have also seen one specimen collected from
New Mexico, but could not subsequently locate the record for confirmation.
Older records also list Colorado, Virginia, and Guatemala in distribution
records for Anuroctonus phaiodactylus. These are probably incorrect.
In southern California, I find this scorpion in well-packed sedimentary
soils, usually, but not always, on sloping ground, especially near the
bases of hills. On Stansbury Island, on the Great Salt Lake in Utah, I
found this species in gently sloping to flat areas of packed, sandy soil.
In Idaho, this species occurs on gently sloping grassland at an elevation
of 4000 feet [Anderson, 1975, Tebiwa, 18(1):1-17]. In all cases, the scorpions
are associated with packed soils and some sort of vegetation. Loose sand
and completely barren ground do not seem to be desirable.
Fun Facts:
- This species spends almost its entire life inside its burrow. Every scorpion
constructs a burrow and there is only one scorpion per burrow. Unlike some
scorpions, which emerge from their burrows to ambush prey, Anuroctonus waits
within its burrow for hapless prey to enter. Because the stinger cannot
be brought to bear within the confines of the burrow, the relatively large,
powerful pedipalps, or claws, are the primary means of subduing prey. Anuroctonus
phaiodactylus can be very abundant in the areas where it occurs. Ordinarily,
several scorpions are found in the same general area. The burrow openings
are readily visible on the soil surface and are oval or cresent-shaped.
Once a search pattern is developed for the burrow entrance, entire colonies
of Anuroctonus are easily discovered. Only adult males leave the
burrow for long periods. This occurs when they go in search of mates. As
a result, nearly all of the Anuroctonus collected by blacklighting
or in a casual fashion are adult males. To collect females, one must excavate
the scorpion's burrow. A military-style entrenching tool is very handy
for this type of work.
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- Mark the burrow by carefully inserting a long, flexible grass stem
or similar object into the burrow and working it down as far as possible.
The tunnel may twist and turn as it spirals down, so this is not always
an easy task. The grass stem will allow you to track the path of the
burrow, even if it becomes obscurred by your digging.
- Dig a wide, 6-to-12-inch-deep hole on the down-hill side of the burrow,
six inches or so from the burrow entrance. It is important that this
digging not disturb the burrow. This hole will give you some working
room and will receive the soil you excavate from directly around the
burrow.
- CAREFULLY, GENTLY remove the soil along the upper reaches of the
burrow so that the grass stem is visible. Always remove the soil from
the down-hill side of the burrow, essentially removing the floor of
the tunnel. This will keep soil from filling the tunnel and when you
reach the scorpion, it will drop right into your excavation hole. Don't
hack in this area unless you like your scorpion in pieces. Also, too
much force can easily pack the loose soil into the scorpion's burrow,
crushing it.
- Continue to gently feed the grass stem into the burrow tunnel. Dig
your excavation hole down another 6 to 12 inches and keep it cleared
of soil. Work slowly and carefully--don't rush.
- Repeat the above steps until you reach the nest chamber and recover
the scorpion!
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- Disclaimer: The views expressed here are mine
alone and do not represent the views of the Department of the Army or
the Smithsonian Institution... or anybody else for that matter. - Dr.
Scott A. Stockwell
