42 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



divide the larvae to species. The adults of 

 all species resemble each other very closely 

 in appearance and general structure, differ- 

 ing chiefly in characters listed in the key. 



KEY TO SPECIES 

 Adults 



1. Apex of abdomen with assemblage of 



sclerotized rods and plates (males), 



fig. 146 2 



Apex of abdomen cylindrical (females), 

 fig. 151 ' 6 



2. Eighth sternite scoop-shaped, not pro- 



duced into a bifid process, fig. 146. . 



erotica, p. 44 



Eighth sternite produced into a bifid 

 process, fig. 150 3 



3. Eighth sternite with apico-lateral cor- 



ner produced into a brushy lobe, 

 and with apex massive and deeply 



and widely excavated, fig. 147 



tenebrosa, p. 43 



Eighth sternite with apico-lateral 

 corner angulate, not produced, and 



with apex more slender, fig. 150. .. . 4 



4. Lateral spine of aedeagus stout and 



abruptly angled near apex, fig. 148. 



maculata, p. 43 



Lateral spine of aedeagus slender and 

 only gradually curved, fig. 150. .. . 5 



5. Lateral spine of aedeagus curved only 



near apex; apex of aedeagus abrupt- 

 ly narrowed at base, fig. 149 



lega, p. 43 



Lateral spine of aedeagus sinuate; 

 apex of aedeagus only gradually 



narrowed at base, fig. 150 



palina, p. 43 



6. Internal plate of ninth tergite with a 



dorsal, bandlike prolongation which 

 is joined to the base of the tenth 

 tergite, fig. 1525; apico-lateral lobes 

 of eighth sternite long, trianguloid, 



fig. 152^ 



maculata, p. 43;lega, p. 43; palina, p. 43 



Internal plate of ninth tergite without 

 dorsal prolongation, fig. 1515; apico- 

 lateral lobes of eighth sternite nar- 

 row, fig. 151^ 7 



7. Internal sternal "whip" attached to a 



TENEBROSA 



Figs. 151-154.— Protopti/a, female genitalia. J, ventral aspect; 5, lateral aspect. 



