ECOLOGIC AND SPATIAL DISTRIBUTION OF 
PYRGUS OILEUS AND PYRGUS PHILETAS 
(LEPIDOPTERA: HESPERIIDAE) 
AT THEIR NORTHERN DISTRIBUTIONAL LIMITS 
By John M. Burns 1 and Roy O. Kendall 2 
Introduction 
In the course of his studies of the world hesperiid fauna, Evans 
(i937> 1949, I95L 1952, 1953, 1955) was — as he himself stated 
(1949: xi) — much influenced by Mayr (1942) and therefore ap- 
plied the polytypic species concept freely in postwar publications. 
Limited mainly to material in the British Museum (Natural His- 
tory), Evans worked with fragmentary distribution data — especially 
for the western hemisphere — and often did not fully digest the data 
he had. (In view of the number of New World species to be treated 
and the uncertain but certainly brief time that remained to him, this 
is no surprise.) As a result, he frequently grouped in a single species 
morphologically related forms that struck him as approximately al- 
lopatric. 
An extreme example of such lumping is Evans’ (1953: 21 1) poly- 
typic species Erynnis juvenalis embracing five subspecies — propertius 
(Scudder and Burgess), meridianus Bell, “ plautus (Scudder and 
Burgess),” juvenalis (Fabricius), and clitus (Edwards) — each orig- 
inally designated as a species. Detailed analyses (Burns i960, 1964, 
in prep.) have shown that this transcontinental assemblage is far 
more accurately described as two distinct superspecies — one western 
and one eastern — that are sympatric in central North America from 
northern Arizona, New Mexico, Texas, and Oklahoma to at least 
the transverse Volcanic Cordillera of southcentral Mexico. Each 
superspecies comprises a pair of allopatric species: E. propertius and 
E. meridianus, on the one hand; and E. juvenalis (which includes 
clitus ) and E. telemachus Burns (which succeeds plautus sensu 
Evans), on the other. [. E . plautus (Scudder and Burgess) is really 
a synonym of E. juvenalis (Fabricius).] Submergence of these four 
species in a single one, in the manner of Evans, obscures rather than 
clarifies evolutionary relationships (see Burns 1964). 
department of Biology, Wesleyan University, Middletown, Connecti- 
cut 06457. 
2 1 3 5 Vaughan Place, San Antonio, Texas 78201. 
Manuscript received by the editor April 8, 1969 
Published with the aid of a grant from the Museum of Comparative 
Zoology. 
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