Savory - Arachnida 1977

122 III. PROLES ARACHNES
CLASSIFICATION
The classification of this order is based on the admirable foundations
contained in "Das Tierreich'" of 1899 and due to Karl Kraepelin. He
divided the living species into six families and his system has been
slightly modified by later workers who have promoted his Diplocentrinae
to the status of a family and have, generally, .separated the
Chaerilidae from the Chactidae.
The Buthidae are the largest family, with over 300 species and more
than 30 genera. They are very widely distributed and are among the
most venomous of their kind. Nearly half the American scorpions
belong to this family. Most of these belong to the sub-family Centrurinae,
which is typically western, but one familiar species, Isometrus
maculatus, is now of worldwide distribution. As its name suggests it has a
yellow body with a number of black spots, and is peculiar in that the
tail of the male is twice as long as that of the female. It has travelled
far, hidden on ships, and is even found on several islands where it has
established itself. The other sub-family, the Buthinae, is mostly an
Old World group, but Ananteris is a small American genus. The best
known scorpion, Buthus occitanus ( = europaeus), the common yellow
scorpion of the Mediterranean, belongs to this sub-family, as does also
Microbuthus pusillus from Aden, which is only 13 mm long and is the
smallest scorpion.
The Scorpionidae are the second largest family, numbering some 150
species in about 20 genera. They are spread throughout the tropics
and are toxic, though not so dangerous as the Buthidae. There are five
sub-families. The U rodacinae include the Australian genus U rodacus,
with only two lateral eyes, and the Hemiscorpioninae are another small
group peculiar to Arabia . .Most of the members of the family belong to
the sub-family Scorpioninae, which is widespread and includes the
largest living species Pandinus imperator and P. gambiensis. The Ischnurinae
are found in both Africa and America and have sometimes been
classified as a separate family, Ischnuridae.
The Diplocentridae are a small, mainly neotropical group, whose
type, Diplocentrus, is Mexican and is also found in Texas and
California. The genus Nebo contains large species from the western
1,1editerranean.
The Bothriuridae are mainly a South American family, but at least
one genus, Cercophonius, is Australian. The typical genus, Bothriurus,
is remarkable for a white patch of membrane on the poison reservoir,
just behind the base of the sting. In this family the sternum is unusual in
that it consists of two transverse plates, broader than long and sometimes
0 0
lnCOnSplCUOUS.
13. THE ORDER SCORPIONES 123
The Vejovidae contain about 45 neotropical species, as well as the
genusjurus from the Mediterranean and Scorpiops from India.
The Chactidae are mainly an American family, but the \vell known
black Euscorpius is found in France, Corsica, Italy and Algeria. It is
sometimes transported accidentally to other parts, but unlike Isometrus
fails to establish itself in distant regions. This family also contains
Belisarius :;,ambeni, the blind scorpion of the Pyrenees. The sub-family
Megacorminae is typically ~lexican. This family also includes Superstitiana,
a genus from the south-western CSA, remarkable for three
stripes on its body, as well as Broteas, whose species, B. alleni, is barely
2· 5 cm long and is one of the smallest scorpions.
The Chaerilidae are a small family of one or two genera, from tropical
Asia.
The last six families are in many ways so distinct from the Buthidae
that these have been considered as representing a distinct line of evolution
within the order.
The families may be separated by means of the following key.
I (2)
2 (1)
3 (4)
4 (3)
5 (6)
6 (5)
7 (10)
8 (9)
9 (8)
10 (7)
11 (12)
12 (11)
CLASSIFICATION OF TilE ORDER SCORPJO:\ES
Sternum longer than or as long as broad
Sternum of two transverse plates and therefore much
broader than long, sometimt>s scarcely Yisible
Proximal end of each tarsus with one extrrnal s:•inc:
sternum clearly pentagonal
Proxim:c~l end of each tarsus \vith two stout spine>;
sternum often pointed anteriorly
No tooth or tubercle below the stin{T
.\ tooth-like spine belmv the sting ,.,
Two lateral eyes on each side, rarely none
Pedipalp with three trichobothria on femur a!l(J not
less than ten on fixed finger
Pedipalp with nine trichobothria on femur and eight
on fixed finger
Three to five lateral eyes on each side
Sternum triangular
Sternum wide, with parallel sides
-·-----··--------·----
·-------·---
3
BOTIIRII.!Rl!lAE
5
7
SCORPIONIDAE
IliPLOCE:\TRlllAE
8
CIIACTIDAE
CII.W.RII.lllAE
11
BUTHIDAE
VEJOVID.-\E
The scorpion has an evil reputation, which it does not deserve. One
of the fev in\·ertebrates that have attracted attention from the earliest
ti~_es, it ha: a place in the Zodiac and a gathering oflegends aud superstltiOus
behefs. Fear of the scorpion is traditional and is partly unfounded;
but is not as foolish as the ideas that it does not drink or that
exposed to fire it commits stiTcide.
'
The biological interest of scorpions is enough to allow us to forget