50 PROC. ENT. SOC. WASH., VOL. 23, NO. 3, MAR., 1921 



ANOTHER ANOMALOUS DIPTERON ADDED TO THE RHYPHIDAE. 



Bv RAYMOND C. SHANNON. 



In connection with the preceding paper by Mr. W. L. McAtee 

 in which the aberrant dipteron Axymyia furcata McAtee is 

 newly described, it seems desirable to publish the following notes 

 on its systematic position. 



Under the title "Rediscovery of the Bibionid Genus Eupei- 

 tenus 1 " Coquillett records his identification of a dipteron as 

 Eupeitenus atra Macq. He is evidently confident of its position 

 in the Bibionidae as he states: "The head and its members, as 

 also the body and legs, are essentially those of Plecia" (Bibioni- 

 dae). 



Critical examination of the same specimen shows that it is 

 not a member of the Bibionidae and the characters given below 

 show that it finds its natural position with the Rhyphidae. 

 The genus Plccia possesses the following characters: Radial 

 sector forking far beyond R-M crossvein; R2 and R3 fused and 

 very short; antennae consisting of scape and an eight-jointed 

 flagellum; scutellum very much reduced and not separated from 

 mesonotum by a distinct suture; Cu2 recurrent at distal end, 

 thus narrowing the anal cell. Axymyia differs in having the 

 radial sector forking well before the R-M crossvein; branch 

 R2-|- R3 long and R2 present as a distinct vein; flagellum of 

 antennae composed of fourteen segments; scutellum well 

 developed and separated from mesonotum by a distinct suture; 

 anal vein evanesces some distance from wing margin, hence 

 anal cell not narrowed at margin. 



Mr. F. W. Edwards has proven that Mycetobia (formerly 

 placed in the Mycetophilidae) is a member of the Rhyphidae. 2 

 The principal character used in both these cases, namely the 

 forking of the radial sector basaci of the R-M crossvein (origi- 

 nally discovered by Edwards), apparently is a fundamental one 

 in the suborder Nemocera. Recently Alexander has added the 

 Trichocerinae to the Rhyphidae. Dr. C. P. Alexander has 

 very kindly examined this manuscript and approves of the posi- 

 tion of the Axymyinae in the Tipuloidea, for which favor the 

 author expresses his sincere thanks. The writer is much 

 indebted to Prof. O. A. Johannsen for a number of points 

 relating to the classification of the Nemocera and for some very 

 timely advice. 



Characters of the Rhyphidae: Radial sector forking anteri- 

 orly to R-M crossvein; anal cell widening towards wing margin; 

 antennae with a many-jointed homomomous flagellum; no 

 true macrochaetae present; ocelli present. This last named 



'Knt. News, p. 106, 1909. Wing figured. 



2 Ann. Mag. Nat. Hist., ser. 8, vol. 17, 1916, p. 108-116. 



