233 



New Australian diptera from ants* nests. 



By Frederick Knab and J. R. Malloch, Bureau of Ento- 

 mology, U.S. Department Agriculture, Washington, D.C. 



Communicated by A. M. Lea. 



[Read October 10, 1912.] 



The Diptera described in the following are an inter- 

 esting addition to the myrmecophilous fauna, particularly 

 the two Syrphidce here described as species of Microdon. 

 While the Microdontinct are believed to be generally myrme- 

 cophilous in the larva state, but very few species have been 

 actually bred from ant nests. There has particularly been 

 some doubt as to the habits of the more anomalous forms, 

 such as these here described; it will thus be seen that differ- 

 ences in the organization of the imago bear no relation to 

 the larval habits. 



All the species of Microdontince so far reported from Aus- 

 tralia show the pedunculate wasp-like abdomen, quite unlike 

 the typical species of Microdon. We were, therefore, at first 

 inclined to put the species from Victoria (M. daveyi) in a 

 separate genus, but a review of the literature and examina- 

 tion of material from remote parts of the world has led 

 us to a more conservative course. It was found that the 

 genus Mixogaster, to which one of the Australian species has 

 been wrongly referred, is quite a distinct concept, and 

 apparently confined to America; Geratophya was poorly 

 denned, and it is extremely doubtful that the Australian 

 species should be referred to it. A last objection arose in 

 the fact that species occur elsewhere which intergrade with 

 the Australian ones in the shape of the abdomen. 



Microdon daveyi, n. sp. 



9 . Dull-black, finely granulose, ornamented with golden 

 pubescence. Frons at vertex at least one-third as wide as 

 head, widening towards the antennae, covered with golden 

 pubescence except on a transverse patch at lower extremity 

 of ocellar triangle ; face projecting immediately below 

 antennae, flattened and nearly straight, perpendicular in pro- 

 file, descending to slightly below lowest level of eyes, thickly 

 covered with golden pubescence ; postocular cilia yellow. 

 Antennae long, the two basal joints ferruginous, the third 

 black, proportions 6-1-12; arista as long as basal joint (6), 

 bare, ferruginous : third joint subcylindrical, very slightly 



