1987] 
Shattuck — Pogonomyrmex occidentalis complex 177 
3a. Propodeal spines absent or, if present, shorter than the distance 
between their bases; venter of petiolar peduncle smooth, with- 
out a process; frontal lobes expanded laterally, without a 
thickened border P. brevispinosus 
3b. Propodeal spines distinctly longer than the distance between 
their bases or, if shorter or absent, then venter of petiolar 
peduncle may possess a broad and short to narrow and long 
process; frontal lobes slightly expanded laterally, with a 
thickened border ( occidentalis subcomplex) 4 
4a. Basal tooth of mandible offset, causing basal margin of 
mandible to form an angle medially P. occidentalis 
4b. Basal tooth of mandible not offset, basal margin of mandible 
even over its entire length 5 
5a. Propodeal spines absent or, if present, distinctly shorter than 
the distance between their bases; thoracic profile arched, with 
an angle present near the mesopropodeal suture; majority of 
workers from a given nest series with a well developed process 
or tooth on the venter of petiolar peduncle 
P. sub dent at us 
5b. Propodeal spines longer than the distance between their bases 
or, if shorter, then without a process or tooth on the venter of 
the petiolar peduncle; thoracic profile flat, without an angle 
near the mesopropodeal suture; venter of the petiolar peduncle 
generally without a process (present in some populations from 
western Nevada and eastern California) 6 
6a. Base of antennal scape angular, with flange present, and dor- 
sum of petiolar and postpetiolar nodes with 5 or more moder- 
ate to heavy rugae superimposed over punctations on posterior 
half. (Known only from the San Bernardino Mountains of 
California) P. montanus 
6b. Base of antennal scape rounded or angular; if angular, then 
dorsum of petiolar and postpetiolar nodes with less than 5 
moderate rugae on posterior half. (Widespread) 
P. salinus 
Summary 
The occidentalis subcomplex of Pogonomyrmex is defined as a 
subgroup of Cole’s (1968) “ occidentalis complex,” consisting of five 
nominal species. Six taxonomically significant morphological char- 
acters are quantified and recorded from throughout the ranges of 
