1976] 
Peck — Beetle Genus Echinocoleus 
57 
New Mexico. San Miguel County. Las Vegas, A. Fenyes, three 
females pinned with Pogonomyrmex maricopa (my determination), 
MCZ, CAS. 
Diagnosis. The species is distinguished by its smaller size, less 
transverse pronotum lacking striae but possessing stiff semi-erect 
hairs, medium fine elytral striae, downward curved aedeagus tip 
in lateral view, and shape of the spermetheca. The species is found 
in upper elevation Chihuahuan desert grassland-woodland habitat, 
in association with Pogonomyrmex ants. 
Description. Body color brown. Size 1.9-2. 3 mm; 1.4-1. 5 mm 
wide; 1 .3-1.5 times as long as wide, widest across pronotum. Pro- 
notum 1 .7-1 .8 times as wide as long. Elytral width across scutellum 
tip 1. 0-1.1 times elytral length from scutellum tip. Stiff semi-erect 
hairs on head, prothorax, and elytra. Pronotal striae absent but 
very fine and light microsculpture present. Elytral striae distinct, 
about three per 0. 1 mm. Aedeagus tip narrower (fig. 12), with termi- 
nal setae, and downcurved tip in side view. Spermatheca with 
shorter crest on flattened anterior bulb (figs. 13-15). 
Variation. No variation is noted. 
Etymology. The name refers to the arid grassland and shrub 
desert region of Texas and New Mexico and adjacent parts of 
Mexico. 
Field notes. The type habitat (in Culberson Co.) is a shrub and 
cactus desert. The dominant plant is perennial broomweed, Xan- 
thocephalum sarothrae (Pursh) Shinners. The beetles were col- 
lected here by digging laterally into the ant nests from the side of a 
small ravine, and aspirating the ants and beetles as they appeared. 
Biology. The beetle is probably widespread in nests of the har- 
vester ant, Pogonomyrmex maricopa Wheeler, throughout much 
of the Chihuahuan region. The ant itself has a wider range in the 
arid southwest (Creighton, 1950; Cole, 1968). Dr. Foster has pro- 
vided the following additional observations. Beetle larvae have 
been found in ant nests only at depths of over two feet, and larvae 
are usually in the presence of ant brood. Both larvae and adults 
appear to be free living, and no contact with the ants or trophallaxis 
or phoresy has been observed. There appears to be a single genera- 
tion per year, with eggs being deposited early in the spring, mature 
larvae appearing by early September, and the winter passed as an 
adult. Additional careful study of the habits of the beetle is needed. 
