A NEW SPECIES OF THE SPIDER GENUS XYSTICUS 
(ARANEAE: THOMISIDAE) FROM ARIZONA* 
By J. H. Redner and C. D. Dondale 
Research Institute, Research Branch, Canada Department of 
Agriculture, Belleville, Ontario 
The North American crab spiders are now comparatively well 
known taxonomically. This is particularly true of the species in the 
large genus Xysticus , which has been twice revised continentally by 
Gertsch (1939, 1953) and treated in more regional works by Buckle 
and Redner (1964), Schick (1965), and Turnbull, et al. (1965). 
It seems probable that any additional new forms that will be dis- 
covered will be from remote parts of the continent or in sibling re- 
lationship with known species. Several species have, however, been 
described only from one sex. 
The purpose of this paper is to describe a distinctive new species 
of Xysticus from the mountainous parts of Arizona. Its structure 
clearly places it in the locuples group of the apophysate division of 
the genus, and its range suggests it to be an inland endemic of the 
southwestern United' States. 
Xysticus humilis sp. n. 
(figs. 1-5) 
Male: Total length 3.45 and 3.16 mm.; carapace 1 .88 and 1.68 
mm. long and 1.82 and 1.59 mm. wide; femur II 1.86 and 1.68 mm. 
long (measurements made, respectively, on the holotype and a para- 
type). Carapace low and smoothly rounded from side to side, being 
little higher at level of legs II than at level of posterior eye row; 
front nearly vertical ; surface with thin coat of short, stiff, recumbent 
setae; eye area and front set with several spiniform setae; orange- 
yellow in color, with indistinct pale V in front of dorsal groove, 
which is uncolored, and with thin black line at side margins. Both 
rows of eyes recurved; ocular quadrangle wider than long, slightly 
wider behind than in front; laterals larger than medians; posterior 
medians only slightly closer to each other than to posterior laterals. 
Legs pale yellowish, I and II slightly darker than III and IV and 
with orange-brown tibiae; femur I with 3-4 weak prolateral spini- 
forms, 1-2 dorsals, o retrolaterals; tibia I with 0-3 weak dorsal spini- 
forms, o prolaterals, 4 pairs of ventrals, o retrolaterals; tarsal claws 
* Manuscript received by the editor January 3, 1966. 
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