1909.] 219 



A NOTE ON THE MALE GENITALIA OF ANISOTOMA ANGLIC A, 

 Rye, and GNATHONCUS NIDICOLA, Joy. 



BY NORMAN II. JOT, M.R.C.S., F.E.S. 



Anisotoma anglica, Rye. 



In the Ent. Mo. Mag,, vol. xli, p. 198 (1905), Mr. Champion 

 gives it as his decided opinion that A. anglica is a form of A. cinnn- 

 momen, apparently because the J posterior femoral characters are 

 similar ; and Dr. Fleischer has also stated that he was unable to 

 distinguish any difference in the fj genitalia of the two forms. 

 Mr. Champion also notes that A. cinnamomea is a very variable 

 species. It certainly varies very much in size, and small specimens 

 differ somewhat in shape from largo ones ; but if individuals of 

 A. cinnnmomea and A. anglica of the same size ai'e compared, 

 i.e., those that have been equally well fed in the larval state (nearly 

 all fungus-feeding species do vary greatly in size and development), 

 it will be found that they differ very little inter se. The general 

 shape is quite different, A. anglica being shorter and having less 

 parallel-sided elytra, in fact, it more resembles A. lucens than 

 A. cinnamomea in outline This is so apparent, that when I first took 

 A. anglica I thought it was a fine specimen of A. lucens when in the 

 net, and I know A. cinnamomea well enough, having taken and bred 

 several hundreds from trufiles sent to me from Wiltshire. In A. an- 

 glica the thorax is more strongly contracted in front and is broadest 

 at the centre (not behind as in A. cinnamomea), and the posterior 

 angles are sharper. 



There are several other minor points of difference. In small, 

 undeveloped examples the differences are not quite so obvious, but 

 are sufficiently well marked. Then the colour of the antennae is 

 certainly of great importance in this genus. It is remarkably con- 

 stant in any given species, and even in A. nigrita, where the insect 

 has a light and dark form, the club is invariably black. A. cinna- 

 momea always has the club of the antennae quite black, in A. anglica 

 the club is, at most, very slightly darker than the basal portion. 

 I have examined the (^ genitalia of several specimens of the two 

 forms, and have no hesitation in asserting that the result of the 

 examination quite settles the question of the specific distinctness of 

 A. anglica, if, indeed, any further proof is wanted. I was careful to 

 compare examples of the same size, and found that the penis in 

 A. anglica is much more slender than in A. cinnamomea : moreover, 

 it is parallel-sided, whereas in A. cinnamomea it is slightly conical 

 in shape, being broadest at the base. 



