102 



Indiana University Studies 



GALL. — A minute. egg--shaped capsule in the aments. Monothal- 

 amous. Each capsule ovate, somewhat elongate, more pointed apically; 

 golden yellow brown, the surface finely pitted like leather; averaging 

 1.5 mm. long by 0.7 mm. wide; thin-walled, entirely hollow. Singly or 

 two or three completely fused; showing clearly the origin from the 

 anthers, sometimes incompletely furrowed, or with parts of anthers at- 

 tached; on the aments of Quercus Douglasii. 



RANGE. — California: Three Rivers. Probably occurs thruout the 

 range of Quercus Douglasii. 



TYPES.— 10 females, 3 males, 27 clusters of galls. Holotype fe- 

 male, paratype adults, and galls at The American Museum of Natural 

 History; paratype females and galls at Stanford University, the U.S. 

 National Museum, and with the author. Labelled Three Rivers, Cal- 

 ifornia; March 23, 1920; Q. Douglasii; Kinsey collector. 



A form on the flowers of the oak must have a short hfe 

 history, with an alternate, probably agamic generation. 



This tiny species is of especial interest because the gall so 

 closely resembles that of Andricus gig as Kinsey, gig as galls 

 differing mainly in being larger, averaging 2.0 mm. in length 

 by 1.0 mm. wide. Gigas was obtained from the same oak, in 

 the same faunal area. I also have gigas from the same flov/- 

 ers which gave this Neiiroterus. Of course the two insects 

 are very distinct, belonging to different genera, even if the 

 name Andricus does not define a genus. Some other species 

 of Cynipidse produce similar galls on the aments. Here is one 

 of the few cases I know among cynipids producing distinct 

 galls where the species and genus of the gall maker is not the 

 primary factor in determining the type of the gall. The 

 anther appears to have only certain possibilities for abnormal 

 development; practically identical results are effected when 

 the stimulus is supplied by either Andricus gigas or Neu^ 

 roterus floricola. Galls of much the same type, altho 

 clustered differently and of several different shapes, are ef- 

 fected by Andricus dubiosus (Fullaway), Andricus serri- 

 cornis Kinsey, Neuroterus pallidus Bassett, and some other 

 species. In fact, I do not now recall any species where any 

 other sort of modification of the anther is produced. The 

 diversity of these insects is great; it would appear to be the 

 nature of the anther which restricts the type of modification. 



Plagiotrichus Mayr 



Plagiotrichus Mayr, 1881, Gen. Gallenbw. Cynip., pp. 8, 12, 32. Dalla 

 Torre and Kieffer, 1910, Das Tierreich, XXIV, p. 388. 



