FAMILY MYCETOPHILID.E — THE FUNGUS GNATS 121 



KEY TO GENERA* 



1. Second basal cell closed apically 2 



Second basal cell open apically 12 



2. Anterior branch of third vein at least half as long as posterior branch; 



auxiliary vein short, ending free; posterior divisions of pronotum with 



one or more long bristles (Ditomyiinge) 11 



Anterior branch of third vein less than half as long as posterior 

 branch, in some cases vestigial or absent; auxiliary vein in most 

 cases long and ending in the costa; posterior divisions of pronotum 

 without long bristles 3 



3. The second basal cell much shorter than the first; first and second basal 



cells separated (Bolitophilinse) (18) Bolitophila Meigen 



The second basal cell almost as long as the first or the basal sections of 

 the third and fourth veins fused for a short distance 4 



4. Both crossveins closing the basal cells present, nearly in a straight 



line; basal section of fourth vein lacking (Diadocidinte) (19). 



Diadocidia Rutlie 

 Basal sections of third and fourth veins fused for a short distance ex- 

 cept in Palteoplatyura in which basal section of fourth vein is present o 



5. Antennae long and slender, in most cases longer than the body (Macro- 



cerinjB) (4) Macrocera Meigen 



Antennce more robust, in some cases distinctly thickened and flatteried 

 (Ceroplatinffi) G 



6. Proboscis prolonged into a snout Asindulum Latreille 



Proboscis not prolonged into a snout 7 



7. Antennae conspicuously flattened; palpi porrect (Heteropterna, Cerote- 



lion, Euceroplatus) (5) Ceroplatus Bosc 



Antennae not conspicuously flattened, palpi curved 8 



8. The anterior crossvein not obliterated by the fusion of the bases of the 



third and fourth veins (20) Paheoplatyura Meunier 



The anterior crossvein not obliterated by the fusion of the base of the 

 third and fourth veins 9 



9. Basal section of fourth vein absent (Isoneuromyia, Neoplatyura, Proeero- 



platus, Lapyruta, Micrapemon) (9) Platyura Meigen 



Basal section of fourth vein present 10 



10. Ocelli wanting; anterior branch of third vein ending in the costa. 



Hesperodes Coquillett 

 Ocelli present, anterior branch of third vein ending in the first vein 

 (21) Apemon Johannsen 



11. Fork of fourth vein distal of fork of third vein (22) . . .Ditomyia Winnertz 

 Fork of fourth vein basal of fork of third vein (14) . . .Symmerus Walker 



12. First and third veins arising separately at base of wing; venation de- 



fective; proboscis elongate (Lygistorrhinae) (Probolaeus) (2, ,3). 



Lygistorrhina Skuse 

 First and third veins arising from a common stem well beyond base 

 of wing • 13 



* Checked by Dr. O. A. Johannsen. 



