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Pseudoscorpions (False Scorpions)
A British Naturalists’ Association Guide
By ROGER TABOR
These tiny animals look just like scorpions,
- but without the stinging tail! Their pincers look just like
those of a scaled down version of a scorpions, and it is the
pincers that contain venom glands to immobilize their small
prey. The prey has to be small for the Pseudoscorpions are
themselves only 2-8 mm long (depending on species).
They are closely related to spiders, so
within the Phylum Arthropoda, they are also in the Class Arachnida,
and have their own Order Pseudoscorpionida. They range in
colour from a pale yellow-brown to a dark brown.
Most people have never seen one, yet not
only are they widespread, it is likely you have some in your
home! There they are far from harmful, and help to control
insect larvae that can cause damage.
There are 28 species in the British Isles,
but they were only beginning to be first identified when the
BNA was born just over a century ago. Around 1911 some keys
were published, and then again in revised form in 1954. The
British Naturalists’ Association played a role in encouraging
a greater interest in recognising and identifying Pseudoscorpions
when it published in its journal ‘Country-side’ a series of
four papers/articles by Gerald Legg. The first two were in
the Spring and Autumn issues of Country-side in 1970, the
first covering general habits, feeding hibernation, reproduction
and life history of Pseudoscorpions, and the second covering
the capture, culturing, feeding and equipment to examine Pseudoscorpions
plus a key to separating them into their families:
Legg, Gerald, (Spring 1970) ‘False-Scorpions’
, Vol. 21. (new
series) No. 6, 262-266.
Legg, Gerald, (Autumn 1970) ‘False-Scorpions:
Their Capture & Care, & Identification of Families’,, Vol. 21, (New Series), No. 8, 367-372.
Then in 1971 and 1972 Gerald Legg produced
Pseudoscorpion species identification keys within first the
families Chthoniidae, Neobisiidae and Cheiridiidae, then the
families Cheliferiidae and Chernetiidae.
These keys in Country-side were a significant
addition to available material on Pseudoscorpions:
Legg, Gerald, (Summer 1971), ‘False-scorpions;
the families Chthoniidae, Neobisiidae and Cheiridiidae’. ,
Vol. 21, (new series) No. 10, 472-477.
Legg, Gerald (Spring 1972), ‘False-scorpions:
the families Cheliferidae and Chernetidae. ,
Vol. 21, (New series) No. 12, 576-583.
Philip Jones at the Institute of Terrestrial
Ecology’s Biological Record’s Centre at Monks Wood Experimental
Station compiled distribution maps of Pseudoscorpion records
published as a Provisional Atlas in 1980. After that in 1982
Gerald Legg took over as recorder, and began a new recording
scheme plus he also wrote the ‘Pseudoscorpions’ synopsis of
the British Fauna (Linnean Society).
In Philip Jones’ Provisional Atlas the
distribution maps often showed a paucity of records, such
as just a couple of historic records for the whole of Britain
for Chthonius halberti, but a few were better recorded, such
as Neobisium muscorum that was observed to be the commonest
and most widespread, and found in a remarkable range of habitats
from in soil to living in bird’s nests. Gerald Legg tried
actively to stimulate more interest in the group by producing
a newsletter, ‘Galea’, that is published by the British Arachnological
Society. In that some ‘English’ names were proposed such as
‘Halberts’ chthonid’ which is decidedly less user friendly
than Chelifer cancroides as ‘House scorpion’!
Over the years most records have come
from either finding them incidentally while searching systematically
for other arthropods, or by semi-casual inspection by turning
stones and leaf litter and prising rotten wood. When a systematic
approach is made the usual method has been placing some of
the material to be inspected (such as leaf litter) into a
white tray and slowly hand sorting. The use of a sieve of
a size that allows the Pseudoscorpions through and leaves
the leaf litter largely behind is an effective technique in
hand sorting. A development of this is to use a Tullgren funnel,
which is in essence just a large funnel in which leaf litter
is placed, and a small electric light bulb suspended over
it (25w). The gentle warmth drives the Pseudoscorpions down
to fall into a collecting vessel. Legg described the techniques
in the Autumn 1970 edition of Country-side.
Since then using garden leaf vacuum machines
(readily obtained from garden centres) has become a recommended
method of the Pseudoscorpion Recorder’ Groups, with the modification
of a fine mesh bag gripped in the inside of the machine’s
entrance by a tie. Once the catch is dropped into a container
Gerald Legg recommends that a few drops of ethyl acetate on
a small pad of cotton wool are dropped into the bag to dope
any spiders to prevent them eating the Pseudoscorpions!
Just a short burst of suction rapidly
removes them from among grass tussocks without destroying
them (as other approaches can), and therefore preferable (especially
in fragile sand dune vegetation).
I have a particular interest in one habitat
and 2 species, as they were first found near to here in coastal
Essex. Neobisium carpenteri was first recorded on the north
east Essex coast in 1958 in plant litter on the salt marsh
and at the base of the sea-wall. This species, that has only
been found in the British Isles, is a deep olive colour, with
red-yellow pedipalps (pincers). Then at the exact same coastal
location in 1961 Chthonius kewi was first discovered as a
species for the British Isles. This species is overall yellow-brown,
with red tinged pedipalps.
© Roger Tabor 2006
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