56 



Indiana University Studies 



RANGE. — Oregon, Idaho, and Utah. Probably elsewhere in the 

 northwest. 



Morphologically the insects of this species are decidedly 

 related to Diplolepis rosx, and less closely to D. bicolor. Sig- 

 nificantly, the galls of variety bassetti show striking similarity 

 to those of roscB. The galls of the other variety, tho super- 

 ficially similar to ros%, are in all respects merely a compact 

 cluster of galls of the D. bicolor type, differing mainly in pos- 

 sessing the filamentous covering. The evolutionary transi- 

 tion from the galls bicolor to rosx, or the reverse procedure, 

 cannot have been more profound than the evolution of the two 

 types of galls in this one species. 



There will be no question that this is a single species, for 

 the characters separating the two varieties are very few. But 

 if one has any doubt of the validity of the varieties he should 

 examine a large series of individuals, when he should be im- 

 pressed with the constancy of the distinctions within these 

 few characters. Geographic isolation has probably contrib- 

 uted materially to the separation of two forms, for as far as 

 the ranges of the two are known at present they are sepa- 

 rated by the high altitudes of the barren lava-bed country of 

 western Oregon. The type localities of the two are two hun- 

 dred and fifty miles apart. Moreover, variety bassetti occurs 

 in a region of excessive precipitation and tempered seasons, 

 while the other variety occurs in the very arid deserts of the 

 northern Rocky Mountains, a country of extreme climate. 



I should not consider this a variety of Diplolepis rosx, 

 tho the two are very close. Rosse seems to be a native of 

 Europe, but has more or less of a world-wide distribution, 

 being readily imported into new regions; and apparently the 

 species reached the eastern part of the United States as an 

 importation from Europe. Rosse has not been recorded from 

 west of the Rockies. No species native to America is very 

 closely related to ros% except this Pacific Coast species, 

 bassetti. There may be considerable significance in this 

 situation. 



Diplolepis bassetti variety bassetti (Beutenmuller) 



Rhodites bassetti Beutenmuller, 1918, Can. Ent., L, p. 307, pi. IX, figs. 

 13, 14. 



FEMALE. — Differs from the female of the other variety as fol- 

 lows: Eyes not protruding beyond cheeks; scutellum closely rugose, 



