1952] 
Creighton — Pogonomyrmex huachucanus 
75 
genus Pogonomyrmex. This point is of interest in view of 
Wheeler’s theory that huachucanus is a relict species. 
According to Wheeler (1) huachucanus and the closely 
allied Chilean species bispinosus are the remains of a primi- 
tive Pogonomyrmex fauna which originated from the genus 
Myrmica in boreal America and subsequently spread south- 
ward through the arid portions of both North and South 
America. This primitive Pogonomyrmex fauna was later 
replaced in large part by more adaptable, modern species. 
The replacement left relict species at widely isolated points 
in the orignal range. This theory, which was designed to 
explain the close structural similarities which mark huachu- 
canus and bispinosus, was necessarily based upon the 
characteristics of the worker of huachucanus. Wheeler 
knew nothing of the male of huachucanus. The structure 
of the male is of particular importance in phylogenetic con- 
siderations and it is interesting to find that this caste shows 
features which agree well with Wheeler’s view. The gen- 
eral appearance of the male of huachucanus is quite unlike 
that of the males of the other North American species of 
Pogonomyrmex. The latter are good sized insects as ant 
males go, with a length of nine millimeters or more. This 
is true even when the worker caste is comparatively small, 
as is the case with desertorum. The surface sculpture is 
variable but it is never heavy enough to produce a com- 
pletely dull surface and, in most cases, the body is distinctly 
shining. The erect body hairs are long, thin, flexuous and 
very abundant. They often mat together but, even when 
they do not mat, they are close enough to each other to 
obscure the parts on which they occur. The antennal scape 
is at least as long as the first three funicular joints taken 
together. The male of huachucanus is an exception to each 
of the above features. It is a small insect, not more than 
seven millimeters long. The sculpture of the head and 
thorax is dense, giving these parts a dull appearance. The 
erect body hairs are well separated, stout, evenly curved 
and notably shorter than those of the other species. They 
do not mat together nor do they obscure the parts on which 
they occur. The antennal scape is less than half as long as 
the first three funicular joints taken together. As to 
whether these features can be considered primitive is a 
