362 PROCEEDINGS OF THE NATIONAL J.IUSEUM vol. loe 



raised, two lateral ocelli; antennae S-segmented, segment I of each 

 antenna fused l)asally or completely fused (fig. 3,c,h), short, attached 

 to ventral surface (female) or anterior surface (male) of antenna! 

 tubercle, inserted well above (male), at, or below mideye height 

 (female), segment II shorter than I, segment III long, with or without 

 apical seta, round, or compressed, with concavity along outer margin, 

 pointed or rounded apically; no visible palpi; proboscis minute, when 

 visible not much longer than rounded, rigid proboscis tubercle in 

 front; occiput narrow or wide; pile dense on occiput, eyes, dense or 

 sparse on antennae; frontal region above and below antennae, occiput, 

 proboscis plate, and lower part of sternopleura and meropleura grayish 

 pollinose. 



Thorax: Convex, strongly arched in front, leveled out behind, 

 covered with dense pile except on lower sternopleura and mero- 

 pleura, near base of halter, and on upper anterior side of postalar 

 callosity; humeri separated by less than head width; squama large, 

 narrow or wide; legs well built, tibiae with one (outer) or two (inner 

 and outer) apical spurs, metatarsus extended (fig. 4,e) or compressed 

 (fig. 4,,^/), three pulvilli, middle one narrowest; wing reaches beyond 

 (female), at, or near tip of abdomen (male), rounded or angled at 

 apex; venation strong; subcosta ends beyond middle of wing, no 

 humeral crossvein, R2+3 incomplete or reaching wing margin, vein R4 

 ends at or before wing apex, no radial, cubital, or marginal veins reach 

 wing margin behind R4 (except possibly in lutescens), and anal axillary 

 vein short, usually not penetrating posterior lobe, four to six posterior 

 cells, only the first and subdiscal ones closed, basal cells nearly even or 

 second basal up to one-third longer, anal cell narrow or widened at 

 apex. 



Abdomen: Compressed dorsoventraily, widest at segment III or 

 IV; six tergites and seven sternites easily visible; genitalia concealed 

 under tergite VII, directed posteriorly, not ventrally; stigmata of at 

 least segments II-IV free, lying in intersegmental membrane, each 

 enclosed by small chitinous ring. 



Remarks: The first posterior cell is divided near the apex of the 

 discal cell, and in this discussion I have interpreted the upper part as 

 the first posterior cell and the lower part as the second posterior cell. 



Key to the species of Plalea Erichson 



1. Antennae inserted on largo tubercle both above mideye height level; wings 



not extending much beyond tip of abdomen [males] 2 



Antennae inserted on small (or large) tubercle, the antennae inserted at 

 or below mideye height level; wings extending beyond tip of abdomen 

 [females] 4 



2. Wing with vein II j+j incomplete 3 



Wing with vein R j+3 complete (Brazil) P. lomata Erichson 



