Occasional Papers of the Museum of Zoology 1 1 



America as far north as about 20" N. All the species known 



for Central America and for the ^Nlagdalena River (Colombia) 



belong in this group. Of group 4, the two species occur in 



British Guiana, and one of these has been recorded from as 



far south as Santarem, Brazil. 



Key to Males of Groups i and 2* 



li} Dorsum of head, prothorax, thorax and first seven abdominal seg- 

 ments largely black, apical half of 8 and 9 and 10 entirely or largely 

 yellow. 

 b\ A wide yellow humeral stripe ; a dorsal black spot on abdominal 



segment 10 flavovittatuiu. 



b". Dorsum of thorax on each side with a yellow oval spot; abdom- 

 inal segment 10 without a black spot ovatuiii. 



a". Not as above. 



1)\ Segments 9 and 10 black above ; head largely pale, markings 

 obscure. 



c\ Segment 8 largely yellow or yellowish above tcfcricuiii. 



c^ Segment 8 black above mclaniirnm. 



W. Segments 9 and 10 pale above (reddish or yellowish), similar 

 to 8 or distal part of 8. 



c\ A broad black posthumeral stripe ; head above broadly and 

 definitely patterned with black. 



d\ Dorsum of thorax largely black ; area below between the 



fork of the mid-dorsal carina black ; mid-area of hind 



lobe of prothorax a definite round black spot. Jriaiigulare. 



d^ Dorsum of thorax, except area of the middorsal carina, 



pale, the area below between the fork pale ; prothorax pale, 



the hind lobe without definite markings bcschkii. 



cl No definite posthumeral stripe ; head above largely pale, 

 markings generally obscure and indefinite. 

 d\ Superior appendages in profile not swollen ventrally at 



base; apex of 7 and all of 8 pale aurantiacum. 



d". Superior appendages in profile swollen ventrally at base; 

 apex of 7 and basal part of 8 black consors. 



Key to Females of Groups i and 2'' 

 a\ Prothorax and thorax dark above, a wide yellow antchumeral stripe, 

 occupying about two-fifths the width of the mesepisternum and cx- 



* For a discussion of cinnamomcum, dorsale, macilentum, obsolelum and 

 ochraceum, known to me only from descriptions and not included in the key, 

 see text. 



5 For a discussion of macilentum, bcschkii and amar.onicnm, the females of 

 which have been described but which arc otherwise not known to me and are 

 not included in the key, see text. 



