igo 
Psyche 
[September 
Mature males, when disturbed, either run or flatten themselves 
against the substrate, but none were observed to “feign death.” 
The function of the vibrating response is unclear. It does not 
resemble the “testing” of web tension, which is accomplished in a 
different manner (see Predatory Behavior above). It may aid in 
camouflage by blurring the visual image received by a predator. 
Vibrating may function in dispersing a defensive chemical, as it 
does for some opilionids, or it may be mimicry of such behavior. 
Another important defensive mechanism is the cryptic coloration 
of Hypochilus (Figure 4), which allows it to blend in remarkably 
well with rock surfaces when in its usual resting position. 
H. thorelli does not display autotomy, a common defensive mech- 
anism among most other spiders. 
Reproductive Biology 
Morphological and behavioral changes. Males mature early in 
August. (I collected the first mature specimen on 5 August; they 
became abundant soon after then until October, and the last one 
was observed on 7 November.) The males undergo their final molt 
in a molting web. This web has a circular base of about the same 
size as the base of the usual web, but the sides of the web extend 
away from the substrate for about 12-15 cm, tapering to a mouth 
somewhat smaller than the base. The mouth is sealed off with a 
loose network of silk. Whether they alter their old webs or move 
to new locations to build the molting web is unknown. The molt- 
ing web probably offers greater protection from predators during the 
(presumably) more difficult final molt. W. A. Shear (pers. comm.) 
reports that the same type of web is constructed by males of H. 
gertschi. 
Sexually mature males are strikingly different in appearance from 
immature specimens and females. In addition to other morphologi- 
cal changes, they develop relatively longer legs (Figure 6) in 
the final molt and the legs change in color from pale yellow and 
brown to dark reddish-brown. The greater length of the legs of the 
males is related to their use as tactile organs during courtship be- 
havior (see below), and may also improve locomotion during their 
search for females (see also below). The reddish-brown coloration 
is a result of heavier cuticular sclerotization, which lends greater 
strength to the elongate appendages. The color is not as cryptic as 
is the normal coloration. 
Several changes in behavior occur with the final molt (see also 
Defensive Behavior above). The males cease feeding, let their webs 
