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Indimia University Studies 



RANGE. — Colorado, Utah, Arizona, and probably New Mexico. 

 Probably thruout the southern Rocky Mountains and adjacent regions 

 wherever Q. Gambelii varieties occur. 



The two known varieties occur in distinct faunal areas of 

 the southern Rocky Mountains of Colorado. Inasmuch as 

 that country involves so many other faunal areas, 

 there are probably many other varieties of the species 

 to be described. I have galls from Q. Gambelii varieties from 

 several localities in Arizona and Utah that probably belong to 

 this species. A, rugulosus Bassett and its varieties produce 

 rather similar galls on evergreen white oaks of parts of the 

 southwest, but those insects are generically distinct from 

 frequens. As far as I know, frequens occurs only on the 

 deciduous white oaks. 



The species is most closely related to P. chrysole'pidicola of 

 the Pacific Coast, and it is not impossible that we shall con- 

 sider these one. species after other, intermediate varieties be- 

 come known. P. elofigatiis of Texas is the next most closely 

 related species, but frequens does not resemble elongatus 

 nearly as closely as it does some of the varieties of chryso- 

 lepidicola. 



Gillette described this species as from Q. undulata. I have 

 seen it only from the white oak with large, long, deciduous 

 leaves; this would appear to be Q, Gambelii, or one of its vari- 

 eties or closely related species, according to the more recent 

 treatments of these difficult oaks. 



Plagiotrichus frequens variety frequens (Gillette) 



Andricus frequens Gillette, 1892, Ent. News, III, p. 247. Dalla Torre 

 and Kieffer, 1902, Gen. Ins. Hymen. Cynip., p. 63. Thompson, 

 1915, Amer. Ins. Galls, pp. 6, 32. Felt, 1918, N.Y. Mus. Bull., 200, 

 p. 59. 



Callirhytis frequens Mayr, 1902, Verh. Ges. Wien, LII, p. 289. Dalla 

 Torre and Kieffer, 1910, Das Tierreich, XXIV, pp. 566, 806, 838. 



FEMALE. — Differs from the other variety of the species as follows : 

 Color mostly dark rufous to black on the head and thorax, varying to 

 almost solid black; antennae rufous basally, black terminally; fovese 

 rather small, distinctly smaller than in the other variety, black; abdomen 

 wholly black; legs including the coxae rufous, hind tibiae dark to black; 

 areolet of moderate size; length 1.7-2.5 mm. 



GALL. — Quite identical with the gall of the other variety. 



RANGE. — Colorado: Manitou. Probably confined to a limited 

 region in Colorado east of the Continental Divide. 



