6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 93 



knowledge will probably place many of our other species of Zenillia 

 in Pantel's group 2. 



Most of the species of Zenillia possess an inner ventral bristle on 

 the midtibia. It will be noticed that this character, as used in the 

 following key, while usually of specific value, is only a secondary 

 sexual character in some species. The Hyphantrophaga and Eusisy- 

 ropa groups have one bristly hair behind on the apex of the hind 

 coxa. Zenillia fulgoris has one very fine and Zenillia virilis has several 

 fine hairs on the apex of the hind coxa. All the other species of 

 Zenillia lack these bristly hairs on the hind coxa. 



KEY TO THE SPECIES OF ZENILLIA 



There are 21 species of Zenillia included in the key. Nine occur in 

 the Nearctic Region, 8 in the Neotropical, and 4 are common to both 

 realms; the genotype libatrix is a Palearctic species. Eight of the 

 species are new, and 4 have been removed from synonymy. Since 

 Zenillia libatrix has been released in the northeastern part of the 

 United States, it is included in the key, but to date there is no evidence 

 to indicate that the species has become established. Chrysophryxe 

 tibialis, new species, is included because the type is labeled as the male 

 allotype of C'hrysoexorista viridis Townsend (U.S.N.M. No. 19611), 

 an included species. 



1. Midtibia usually with one median anterolateral bristle; if with a smaller 



additional one, then facial ridge is never bristly on more than lowest 



one-fourth 3 



Midtibia with two or more median anterolateral bristles 2 



2. Midtibia with two median anterolateral bristles, upper one smaller ; palpus 



yellow, facial ridge bristly to middle 1. libatrix (Panzer) (p. 8) 



Midtibia with three or more median anterolateral bristles ; palpus black ; 

 parafacial with a dark-brown reflecting spot just below lowest frontal 

 bristles 2. futilis (Osten Sacken) (p. 11) 



3. Discal macrochaetae present on second and third abdominal segments 6 



Discal macrochaetae absent on second and third abdominal segments 4 



4. Three postsutural dorsocentral macrochaetae; palpus rufous, black toward 



base, extreme tip yellow ; midtibia with one strong median anterolateral 

 bristle and a smaller one below (male only) 



3. angustata (Van derWulp) (p. 12) 



Four postsutural dorsocentral macrochaetae: palpus yellow; midtibia usually 



with one median anterolateral bristle i 5 



5. Antenna with first and second segments rufous, third black; facial ridge 



bristly on lowest one-fifth; legs black, tibiae brownish black; abdomen 

 with dorsum completely covered with gray pollen, which extends on to 

 dorsal shoulders of first segment; dorsal vitta indicated at least on second 



segment 4. euchaetiae, new species (p. 13) 



Antenna with first and second segments and in female base of third segmenl 

 yellow, remainder black ; facial ridge bristly on more than lowest one-fifth, 

 often nearly halfway; legs reddish brown; abdomen in male with narrow 

 apical margins of segments 2, 3, and 4 brownish black, adjacent pollen 



