1986] Rissing, Johnson, & Pollock — Acromyrmex 179 
September and 4 October 1985. All queens excavated 1-2 days fol- 
lowing the mating flight were found 5-10 cm below the soil surface. 
The possible importance of relatedness in formation of queen 
associations was tested according to the methods of Rissing and 
Pollock (1986). Eight plastic “choice boxes” (30 X 15 X 8 cm, half 
filled with sand moistened in each corner and at the midpoints along 
the long sides) were established with 2 sets of 4 queens, one set 
collected from each of the two study sites (38.5 km apart). In 5 boxes, 
queens were color marked according to collection locale; different 
patterns of the same two colors were used to avoid providing cues 
for recognition. As an additional control for possible paint odor, 
queens in the remaining 3 boxes were not marked. Boxes were 
excavated 24 hrs later when queens had dug below the surface; 
location of each queen was noted relative to the others. 
Results 
Acromyrmex versicolor queens strongly prefer to start nests 
immediately below the outer canopy of trees; while mean inter-tree 
distance was 6.10 ± 1.85 canopy units (= 21.37 ± 5.14 m between 
tree bases; N = 20), the average starting nest was .87 ± .53 canopy 
units (= 3.15 + 1.88 m; N = 1 15) from a tree base (Fig. 1). Although 
measurements were not taken, the same distribution of starting 
nests was observed at South Mountain Park. All queens examined 
for temperature tolerance survived exposure to temperature up to 
and including 40° C for at least 2 hr; survivorship was 0, however, at 
42.5° C and above. Temperatures above 40° C were found in the 
open between trees (>1 canopy units) at soil depths normally occu- 
pied by newly starting colonies (X 5 cm = 42.0 (± 1.1)° C, N = 5; 
Xjocm = 36.9 (± 1.2)° C, N = 10); temperatures this high were not 
found at canopy edges (= 1 canopy unit) (X 5 cm = 38.2 (+ 5.5)° C, N 
= 5; Xjocm — 32.8 (+ 3.7)° C, N = 9) or at tree bases (= 0 canopy 
units) (x 5cm = 28.91 ± 2.4), N = 2; x 10cm = 27.4 (± 0.8)°C, N - 5). 
Acromyrmex versicolor is highly pleometrotic; 82.5% of all 
queens excavated (N = 160 queens from 64 nests) were from 
pleometrotic associations (Table 1). Relatedness appears unimpor- 
tant in a queen’s decision to enter a foundress association; five of the 
8 “choice boxes” resulted in a single starting nest occupied by all 8 
queens. The remaining 3 boxes had two starting nests each: of these 
6 starting nests, 4 contained queens from both collection locales, 1 
