1987] Shattuck — Pogonomyrmex occidentalis complex 163 
SI: Scape Index (SL X 100)/ (HW) where: 
SL is the scape length (maximum length of the scape exclusive of 
the radicle). 
HW is the head width (maximum width of the head in full face 
(dorsal) view, exclusive of the eyes). 
Analysis of Character States 
In this section the species concepts of Cole (1968) are maintained. 
Each character is considered separately by species, or pair of species 
where applicable. In the next section each species is considered 
individually and specific taxonomic changes proposed. Data are 
pooled and analyzed by county within each species or group of 
species. Figures 23 through 36 represent the character distribution 
data graphically. Each bar graph represents pooled data for one 
county, with the vertical axis representing frequency and the hori- 
zontal axis representing the character states (state 1 on the left, state 
5 or 6 on the right). The number of specimens represented is indi- 
cated and each graph is located at the approximate center of the 
area pooled. 
Gaster 
Pogonomyrmex occidentalis possesses Gaster states 1, 2 and 3 
(Table 1) distributed randomly, with all states occurring in all areas 
of the range in roughly equal proportions (Fig. 23). 
Cole (1968) stated that in P. salinus the “base of dorsum of first 
gastric segment [is] frequently densely and coarsely punctate and 
opaque, sometimes only very finely punctate or densely shagreened 
and subopaque or shining,” while for P. owyheei it is “as in occiden- 
talism which has “light to moderate shagreening which does not dull 
the shining surface”. These characterizations were confirmed in the 
present study. The gaster of P. salinus may possess any of the states, 
with state 1 the least common and state 5 the most common (Table 
1). In P. owyheei, most specimens possess states 1, 2 or 3, with states 
4 and 5 represented in lower frequencies (Table 1). Thus while this 
character is of some value in distinguishing these two forms, there is 
frequent overlap with 80% of the P. owyheei and 44% of the P. 
salinus specimens showing Gaster states 2 or 3. 
