ABT. 23 REVISION OF MACROCENTEUS — MUESEBECK O 



KEY TO THE NBABC11C SPECIES OF MACROCHNTBUS ' 



1. Maxillary palpi short, not distinctly longer than height of head ; 



labial palpi very short, shorter than the face, even the apical 

 segment but little longer than thick ; antennae 24 to 40 seg- 

 mented ; head always black ; small species, normally measur- 

 ing 3 to 4.5 mm. in length 2 



Maxillary palpi u.sually much longer than height of head; very 

 rarely not distinctly so, but then head is not black ; labial 

 palpi rarely shorter than face, the apical segment usually 

 three or more times as long as thick ; antennae normally 

 40 to 60 segmented 5 



2. Second intercubitus lacking ; nervellus inclivous, much longer 



than lower abscissa of basella, the latter hardly one-fourth 

 as long as mediella ; antennae 24 to 30 segmented ; ovipositor 

 sheaths a little longer than abdomen, but much shorter than 

 body ; thorax and abdomen mostly piceous or blackish, with 



prothorax and mesothorax paler 1. incompletus, new species 



Second intercubitus distinct though often hyaline ; nervellus at 

 least no longer than lower abscissa of basella, the latter less 

 than one-third mediella ; antennae usually 30 to 40 segmented ; 

 ovipositor sheaths at least as long as the body 3 



3. Legs short and rather stout ; anterior basitarsus not distinctly 



half as long as anterior tibia ; apical segment of anterior 

 tarsus as long as the second ; longer calcarium of posterior 

 tibia half as long as basitarsus; antennae distinctly shorter 

 than the body, second flagellar segment only twice as long as 



thick; thorax and abdomen black 2. crassipes, new sijecies 



Legs very slender ; anterior basitarsus more than half as long as 

 anterior tibia ; apical segment of anterior tarsus much shorter 

 than the second ; longer calcarium of posterior tibia much less 

 than half as long as basitarsus; antennae longer than the 

 body, second flagellar segment more than three times as long 

 as thick; thorax and abdomen usually more or les.s yellowish 4 



4. Eyes small ; cheeks broad and strongly convex in both sexes ; 



female antennae normally 32 to 35 segmented, flagellum 

 mostly brownish piceous except three or four basal segments. 

 which are yellowish; male thorax more or less blackish or 

 piceous, mesonotum and sometimes entire thorax blackish. 



3. crambivorus Viereck 

 Eyes not especially small; cheeks gradually receding; female 

 antennae normally 37 to 39 segmented, flagellum yellowish 

 with apical half somewhat fuscous; thorax in both sexes 

 yellow, with pronotum and propodeum dusky or blackish. 



4, crambi (Ashmead) 



» In the key, as well as in the descriptions and discussions that follow, much use has 

 been made of venational differences. The terminology employed is that proposed by 

 Rohwer and Gahan, Morismology of the hymenopterous wing, Proc. Ent. Soc. Washington, 

 vol. 18, pp. 20-76, 1916. 



