A Revision of the North American Species 



OF THE 



Dipterous Genus Diaphorus. 



M. C. Van Duzee 



In separating the genus Diaphorus from Chrysotus I have 

 found no better method than that proposed by Prof. J. M. Aldrich 

 in his paper on the Dolichopodidae of Grenada, Kansas Univer- 

 sity Science Bulletin, vol. i, p. 85, 1902. To place in Chrysotus 

 all species in which the eyes of the male are approximated below 

 the antennae and in Diaphorus all in which they are approximated 

 above the antennae ; where there is no approximation to refer to 

 Chrysotus all in which the male have no large bristles at the tip 

 of the abdomen. Nearly all the species falling in Diaphorus by 

 these rules have the pulvilli of the fore and sometimes those of 

 the middle and hind tarsi enlarged, and also have more or less 

 distinct bristles at the tip of the abdomen ; there are exceptions 

 but one of these characters is always present to determine the 

 position of the species. I do not know of any species that could 

 be placed in Chrysotus by this method of separation that have 

 bristles at the tip of the abdomen larger than those on the hind 

 margins of the other segments, and only a few species in which 

 the fore pulvilli are enlarged and then not conspicuously so, the 

 group to which Chrysotus discolor Loew, belongs have the pul- 

 villi enlarged as much as any I have seen in that genus. The 

 Diaphorus are usually more slender and the abdomen more cylin- 

 drical than those of the Chrysotus. The third and fourth longi- 

 tudinal veins are nearly straight and parallel beyond the posterior 

 cross vein, except in D. simplex Aid. and D. repandus n.sp. where 

 they are bent. (Fig. 11). 



Prof. J. M. Aldrich has called my attention to the separation 

 of the Diaphorus into two genera by Kowarz ; the characters 

 given in his table to separate them are "Wings oval, eyes of the 

 male broadly separated on the front, Melanostolus ; Wings wedge- 



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