AET. 23 REVISION OF MACEOCENTRUS MUESEBECK 9 



Maxillary palpus with longest segment usually longer than sec- 

 ond segment of autennal flagellum ; stigma most frequently 

 uniformly brown or yellow; nervulus usually postf ureal by 

 about its own length ; usually second and third tergites more 

 or less blackish as well as the first and sometimes the follow- 

 ing in part ; second tergite most frequently longer than broad 

 and usually completely aciculate; male scape swollen 24 



22. First abdominal tergite unusually stout, usually not more than 



one and one-half times as long as broad at apex ; distance be- 

 tween spiracles of first tergite at least half the basal width of 

 propodeum; antennae normally 50 to 54 segmented; clypeus 

 about as broad as length of scape and broadly strongly emar- 



ginate at apex 19. robustus, new species 



First tergite not esiiecially stout, usually twice as long as broad 

 at apex ; distance between spiracles of first tergite much less 

 than half the basal width of propodeum ; antennae normally 

 42 to 48 segmented ; clypeus not so broad as length of scape 23 



23. Mesonotal lobes, and mesosternum posteriorly, black; sec- 



ond abdominal tergite usually completely finely aciculate, 

 the third more weakly so on basal half ; ocell-ocular line twice 

 as long as diameter of a lateral ocellus ; mes^opleurum closely 



punctate and subopaque below 20. nigripectus, new species 



Mesonotal lobes and mesosternum never black ; second abdomi- 

 nal tergite usually smooth apically, the third rarely with dis- 

 tinct aciculations ; ocell-ocular line not twice the diameter of 

 a median ocellus; mosopleurum smooth and shining. 



21. ancylivorus Rohwer 



24. Face, viewed from in front, only very little, often indistinctly, 



broader than long; antennae usually 45 to 50 segmented; 

 stigma usually uniformly brown, occasionally entirely pale yel- 

 low ; mesoscutum posteriorly sharply emarginate, the scutellar 

 furrow scarcely transverse ; dorsum of thorax and abdomen 

 most frequently largely blackish or piceous, though rarely 

 almost entirely yellow ; length normally 4 to 5 mm. 



22. instabilis, new species 

 Face much broader than long ; antennae usually more than 50- 

 segmented ; mesoscutum not so sharply emarginate at apex, 

 the scutellar furrow strongly transverse ; length usually 6 

 to 7.5 mm ^ 



25. Second abdominal tergite completely aciculate and usually dis- 



tinctly longer than broad at apex, the depressed lateral 

 margins not much broadened at base of tergite ; third tergite 

 aciculate on basal half; prescutum prominently elevated, de- 

 scending almost vertically in front ; head thin, cheeks not 

 wider than temples, as viewed from side ; rather uniformly 

 yellowish ferruginous, mesonotal lobes not blackish. 



23. utilis, new species 

 Second abdominal tergite usually mostly smooth apically and 

 usually hardly as long as broad at apex, the depressed lateral 

 margins much broadened at base of tergite; third tergite 

 usually not, or only indistinctly, aciculate; prescutum not 

 strongly convex, descending more gradually in front; cheeks 



98306—32 2 



