164 
Psyche 
[September 
2. Phyllophora sp. * (Fam: Phyllophorinae) 
Specimens of this robust dark-green insect assumed diurnal resting 
attitudes on small branches. In the process the long third legs were 
folded at the femorotibial joint so that the tibia was closely apposed 
to the femur (inside edge to inside edge) and the apparent unit 
formed in this way was then tucked beneath the lower edge of the 
tented tegmen (its anatomically anterior margin). On one occasion 
when we filmed the process the insect brought first one tarsus for- 
wards to the jaws, beneath the body, then the other. The tarsal 
region was groomed, in each case, and then the folding process was 
finished and the leg fitted into its cryptic stance. As the long hind 
legs are fitted into position beneath the tegmina the insect settles 
down so that its ventral surface is in contact with the substrate. At 
this stage legs I & II brace the resting insect. Interestingly enough 
the coloration of the outer margin of the tibia III was much paler 
(with pink overtones) than the rest of the joint. This coloration 
closely matches that of the ventral surface of the abdomen against 
which the folded unit is apposed. This coloration is visible only 
when the insect is viewed from below. Figure 2 shows the process 
of leg-folding and the final cryptic posture. We observed similar 
behavior in a very much larger phyllophorine that we did not collect. 
Discussion 
The Phyllophora sp. device can be regarded as primarily an adap- 
tation for concealing the large (“characteristic”) jumping legs of the 
orthopteran. This conclusion is based on comparison with function- 
ally similar devices in other insects and is supported by the fact that 
the posture is adopted during the period of diurnal immobility when 
the insect is presumably at risk from visually hunting predators. On 
the other hand it is not a form of cryptic behavior consistent with 
the main line of evolution of leaf-mimicry in the Tettigoniidae. In 
that line leaf-mimicry has been achieved by flattening in the sagittal 
plane and reduction in the length of the tegmina (examples in 
Chopard 1938, Robinson 1969b). 
The cryptic posture adopted by Acauloplacella immunis is a most 
interesting one in that it reduces profile and affords leg-concealment 
at the same time. It does not involve any marked dorso-ventral 
flattening in the active insect. It is an adaptation that is essentially 
more similar to the postural flattening of bark-living frogs and geckos 
(see Cott 1940) than other forms of crypsis found in the Orthoptera. 
♦Close to P. cheesmanae and P. similis de Jong. 
