42 
Psyche 
[March 
A number of apparently hasty couplings of this kind have been 
uncritically repeated in the current synonymic list of Nearctic Rho- 
palocera (dos Passos 1964). Examples may be found in such genera 
as j Erynnis, Pyrgus , Staphylus, Cogia, Amhlyscirtes , and Panoquina. 
Thus Evans’ interpretations receive empty endorsement and wider 
dissemination when, in fact, they require re-examination. 
Pyrgus oileus and P. philetas are separate species 
Evans (1953: 222) erroneously set Pyrgus philetas Edwards as a 
subspecies of Pyrgus oileus (Linnaeus), and dos Passos (1964: 19) 
echoed this action. MacNeill (1962: 101) meanwhile emphasized 
their distinctness : “The two species are broadly sympatric in Mexico 
and I have taken them together at several widely separated localities 
on the mainland [as opposed to peninsular Baja California, where 
only P. philetas is known].” More recently, Freeman (personal com- 
munication) also has found these two forms coexisting in mainland 
Mexico. 
Central to any taxonomic interpretation is the fact that, even with 
spatial and temporal coexistence, P. oileus and P. philetas differ in 
diverse characters of facies and morphology. These include (1) color- 
pattern of the wings — particularly (a) the ventral surface of the 
secondary, which, in philetas , is characteristically blanched and much 
less marked by sharp contrasts than it is in oileus ; and also ( b ) the 
dorsal surface of the male primary, which, in the proximal third of 
space ib, almost always has 1 or 2 white spots in philetas that are 
virtually or (in nearly all individuals) quite lacking in oileus ; (2) 
the density, length, and orientation of white hair-like scales on the 
dorsal surface of the male primary — these scales are abundant, ex- 
ceedingly long, and directed obliquely distad-and-caudad in oileus } 
but are less common, short, and directed chiefly distad (not caudad) 
in philetas ; and ( 3 ) the genitalia in both sexes (figs. 1-4). These 
distinguishing characters are various and complex enough that control 
of them by a single genetic switch mechanism is unlikely in the ex- 
treme. One may safely conclude that P. oileus and P. philetas are 
not polymorphic variants. 
Genitalia differences are so pervasive and conspicuous, and so 
adequately shown in figs. 1-4, as scarcely to warrant verbal comment. 
Yet it may be worth directing specific attention, in males (figs. 1 
and 2), to the relative lack of spines on the valvae in oileus , the 
medial extension of the anterodorsal part of the distal process of the 
valvae in philetas , the longer saccus and adjacent longer valval articu- 
lation in oileus , the median keel and flanking concavities of the dorsal 
