212 



Illinois Natural History Survey Bulletin 



Vol. 23. Art. 1 



between convex Ri and convex Cui, 

 fig. 734 2 



2. M apparently not branched, fig. 734 



Oecetis, p. 236 



M obviously branched, fig. 735 3 



3. Epicranial stem distinct, lateral su- 



tures absent or indistinct, fig. 736; 

 katepisternum constricted at apex, 



fig. 739 4 



Epicranial stem absent or indistinct, 

 lateral sutures well marked, fig. 738; 



Fig. 736. — Mystacides sepulchralis, head. 



Fig. 737. — Selodes vernalis, head. 



Fig. 738. — Athripsodes tarsi-punctatus, head. 



Fig. 739. — Mystacides sepulchralis, meso- 

 pleuron. 



Fig. 740. — Leptocella albida. 



Fig. 741. — Athripsodes transversus. 



em, mesoepimeron; ep, epicranial stem; k, 

 katepisternum; Is, lateral suture. 



katepisternum truncate at apex, fig. 

 740 5 



4. Dorsal triangle of head small, epicra- 



nial stem long, fig. 737; color whitish, 



straw yellow or light brown 



Setodes, p. 256 



Dorsal triangle of head large, epicra- 

 nial stem short, fig. 736; color very 

 dark brown or bluish black, includ- 

 ing wings Mystacides, p. 253 



5. Meso-epimeron membranous nearly to 



ventral margin, fig. 740; hind wings 

 with most of Rs and its branches 



atrophied; ground color white 



Leptocella, p. 213 



Meso-epimeron with a wide sclero- 



tized bridge between membranous 



area and ventral margin, fig. 741; 



• hind wings with Rs and its branches 



present; ground color not white. . . 6 



6. Front tibiae with 2 apical spurs 



Athripsodes, p. 221 



Front tibiae without apical spurs. . . . 

 Leptocerus, p. 212 



Leptocerus Leach 



Leptocerus Leach (1815, p. 136). Genotype, 

 monobasic: Phryganea interrupta Fabricius. 



Ymymia Milne (1934, p. 16). Genotype, 

 monobasic: Setodes americana Banks. 



The curious translucent case, the hooked 

 middle leg and anal tufts of the larv,ae, and 

 the genitalia of the adults readily distinguish 

 the only North American species of this 

 genus. 



The type of case, structure of larva and 

 adult venation leave no doubt but that 

 americanus is congeneric with the genotype, 

 which is European. This necessitates re- 

 ducing Ymy?nia to synonymy and resurrect- 

 ing Setodes for the group of species for 

 which Milne used the name Leptocerus. It 

 is interesting to note that within both these 

 groups the male genitalia vary greatly in 

 shape. 



Leptocerus americanus (Banks) 



9. 



Setodes americana Banks (1899, p. 215); d^, 

 Setodes grandis Banks (1907^, p. 128); c?. 



Larva. — Fig. 742. Length 6-7 mm. Head, 

 pronotum and legs straw color, the head 

 and pronotum with many black spots. Gula 

 somewhat heart shaped. Mandibles short, 

 truncate at end. Middle leg with claw 

 hooked, tibiae with rounded mesal teeth. 



