AKT. 9 FLIES OF THE FAMILY SYRPHIDAE SHANNOX 3 



D\ Second abdominal segment strongly constricted and several times 



longer than broad, or abdomen very long and slender throughout. 



E\ Third longitudinal vein deeply constricted into first posterior cell. 



Salpingogaster Schiner. 

 E^ Third vein moderately curved downwards or straight. 



Baccha Fabricius. 

 D^ Abdomen parallel sided or moderately constricted basally. 



E\ A distinct row of stiff, erect hairs across anterior margin of 



mesonotum Ocyptamus Macquart. 



E^ Without a distinct row of erect hairs across anterior margin of 

 mesonotum. 

 F\ Apical cross vein (post angular section) upright; a distinct black 

 spot at apex of wing; second abdominal segment moderately 



constricted Calostigma, uew genus. 



F^ Apical cross vein directed obliquely outward ; wing without a 



black spot Mesogramma Loew and Allograpta Osten Sacken. 



B^ Humeral calli and region between them more or less covered with pile ; 

 male, and sometimes female, with only four visible abdominal segments 

 (sometimes three) exclusive of hypopygium. 

 C\ Antennae usually very elongate (either the first or third joints or both, 

 elongated) ; discal cross vein joining discal cell well before the 

 midde; stlgmatical cross vein present; apical cross vein (post angu- 

 lar section) usually upright; spurs usually present on either the 

 third or fourth vein which projects into first posterior cell ; nieta- 

 sternum girdled with chitin ; hind basitarsus usually thickened. 



MICKODONTINAE. 



D'. Second abdominal segment greatly broadened on basal half, strongly 

 constricted on apical half ; face swollen below. 



Rhopalosyrphus Giglio-Tos. 



D'. Second segment not broadened basally and constricted apically ; face 



uniformly sloped. 



E\ Third vein with or without a spur; fourth vein without spurs; 



abdomen constricted on basal half of second segment or behind 



the third, or abdomen more or less ovate Microdon Meigen 



E^ Third vein without spur but a spur present on the fourth vein and 

 on apical cross vein ; abdomen constricted on basal half of second 



segment Mixogaster Macquart. 



C. Antennae rarely elongate; discal cross vein joining discal cell at or 

 before middle; stigmatical cross vein rarely present (sometimes in 

 Eristalinae) ; apical cross vein usually directed obliquely outward; 

 third vein without, fourth vein rarely with spurs ; metasternum 

 usually membranous behind ; hind metatarsus not thickened. 

 D^. Arista with either long or very dense and short plumosity ; face pro- 

 duced downwards ; apical cross vein usually strongly recurrent on 

 distal end ; marginal cell usually closed ; hypopeura with a tuft of 



pile ; thorax usually with bristles volucellinae. 



D'. Arista bare or very thinly pilose ; apical cross vein not, or very 

 slightly recurrent on distal end (except Alipumilio) . 

 VJ. Third vein deeply looped into first posterior cell; facial slopes 



pilose ; metasternum pilose eristalinae. 



Fi. Marginal cell closed and petiolated. 



G\ Thorax and abdomen with bands of tonientum. 



Meromacrus Rondani. 



