1985] 
Wheeler & Holldobler — Cryptic phragmosis 
339 
porrasi (referred to in the remainder of this paper as Z. pallens 
porrasi ). The soldier is characterized by large brush setae on the 
cephalic disc (Fig. 7). Similar views of the two soldiers, one clean 
and one dirty, are shown in Fig. 8. In the soldier that appeared 
clean, the brush setae were free of accumulated material, but the 
surface seemed to be obscured by a thick encrusting material (Figs. 
7, 8a). The second soldier had such a thick accumulation that the 
large brush setae were almost completely buried (Figs. 8b, 9a). The 
material on the head of the dirty soldier appeared fibrous (Fig. 9b), 
much like the material seen on the head of Z. varians (Fig. 3a). 
Z. setulifer (Figs. 10-11). The MCZ collection includes 3 queens 
and 1 soldier of this little-known species. The heads of all 4 speci- 
mens are caked with debris. We examined one queen and found that 
the material encrusting the head appeared more solid than that seen 
in the other species. Brush setae on the head, as far as they can be 
seen (Fig. 10b), were not as complex as those on Z. pallens porrasi. 
On the thorax, where the hairs were visible, were two layers of setae: 
erect brush hairs and a lower layer of flattened appressed setae (Fig. 
1 1). The same pattern was found on the thorax of the soldier. 
Discussion 
Wheeler (1942) was the first to suggest that the encrusting material 
found on the heads of soldiers and queen in two different cephalo- 
tines functioned as camouflage for the nest entrance. His description 
of Z. pallens var. porrasi was based primarily on the large, sparse 
hairs on the heads of soldiers and queens. He commented that the 
cephalic disk of older soldiers and the queen were often coated with 
“dirt and extraneous particles so that it closely resembled the bark 
of the plant.” In addition, he gave the first description of the soldier 
caste for Z. setulifer and noted that the cephalic discs were encrusted 
with “foreign matter from exposure to the elements during guard 
duty at the oval nest entrance.” 
The soldiers, and perhaps the queen during early stages of colony 
development, act as living gates at colony entrances. Clean, shiny 
head surfaces might be more easily spotted by visual predators, such 
as birds and lizards, which could break open twigs for the rich 
reward of ant brood. The resemblance of heads to bark would 
effectively conceal the location of the nest and nest entrance. 
The use of accumulated debris as camouflage has been found in 
basicerotine and stegomyrmicine ants. These are unusually slow, 
