Savory - Arachnida 1977

15. THE ORDER UROPYGI 133
15
The Order Uropygi
[Thelyphoni Latreille, 1804; Thelyphonida Cambridge, 1872;
Cropygi Thorell, 1882; Holopeltidia Borner, 1904; Thelyphonides
~fillot, 1942]
(Whip-scorpions, Vinegaroons; Vinaigricrs; Geiselskorpione)
Arachnida in which the prosoma is longer than broad and is covered by an
individual carapace, on which there are eight or I 2 ryes. The opisthosoma
is of 12 somitfs; the first W)' narrow and the last three A
whip-like jointed telson is present. The sternum is of three sternites. The
first opisthosomatic sternite is ve1y small, the second the third and
fourth are both narrow. The chelicerae are of two undulate. The
pedipalpi are
their coxae fitsed in the middle line and other
with spine-like projections at theu distal ends. The are
pair with many sub-segmmts to the tarsi. Opistho­
. and acetic acids.
The prosoma of C ropygi is covered by a uniform carapace, almost
rectangular in shape and longer than broad. Slight indentations, due
to muscles within, can be seen on its surface. The eyes are in three
groups. A pair of direct eyes occupies the centre of the carapace near
its fore-edge; and on each side, at the level of the first coxae, there is a
group of three or of Thus the total number is eight or 12.
The opisthosoma is a smooth elongated oval of 12 somites (Fig.
38). The first of these is reduced to form a pedicel and has only a very
small and concealed sternite. Those following, from the second to the
ninth, are all protected by transverse tergites. In some species these
reach from side to side without a break, in others a median cleft
divides the tergite into right and left halves. This diYision may be found
in all tergites except the last three; or in the first three only; or again it
may not divide the fourth, fifth and sixth sternites. The last three somites
are much smaller; their tergites and sternites are united and they form
FIG. 38. e ropygi; dorsal aspect. Species, Thelyphonus insularis.
the post-abdomen or pygidium. On the twelfth opens the anus and the
paired glands which, secreting formic and acetic acids, are the animal's
very characteristic mode of self-defence. Equally characteristic, and
responsible for the name of "whip-scorpions", is the long flagellum,
which also arises from somite 12. It has many small segments, perhaps
30 or 40 in number, and is described as a telson. Its "segments" have
therefore no homology with the somites of the body; as an anatomical
feature its homologues are the sting of the scorpion and the very short
flagellum of Schizomida.
The last or anal somite, from which the telson or flagellum arises,
carries on its dorsal surface a pair of pale patches called ommatidia er,
better, ommatoids. They have not been shown to be sensitive to light
and their function is unknown.
The comparative simplicity of the upper surface of the body is not