August, 1944 



Ross: Caddis Flies of Illinois 



223 



10. 



Anterior margin of pronotum with 

 well-separated hairs of nearly equal 

 length, fig. 767 transversus, p. 233 



Color pattern and spots more con- 

 trasting, fig. 765 



tarsi-punctatus, p. 229 



Color pattern and spots less contrast- 

 ing, fig. 764 alagmus, p. 229 



Adults 



1. Genitalia with movable claspers, figs. 



774-791 (males) 2 



Genitalia without claspers, figs. 792- 

 807 (females) 19 



2. Claspers with a basal projection nearly 



as long as height of clasper, fig. 774 3 

 Claspers with either a short basal pro- 

 jection or none, figs. 780, 791 4 



3. Basal projection of claspers evenly 



rounded, fig. 774 ancylus, p. 227 



Basal projection of claspers angled, 

 fig. 775 flavus, p. 228 



4. Tenth tergite U-shaped, the base form- 



ing the bottom of the U, the ventral 

 arm of the U divided into lateral 

 halves, each tipped with a cluster of 



spines, fig. 776 saccus, p. 234 



Tenth tergite not U-shaped, some- 

 times long and necklike, fig. 778. . . 5 



5. Claspers with a serrate, mesal lobe; 



tenth tergite divided by a narrow 

 fissure into dorsal and ventral parts, 

 the ventral lobe with a strong, long, 

 lateral blade, fig. 777. .erraticus, p. 235 

 Claspers without a serrate mesal lobe; 

 tenth tergite not divided into dorsal 

 and ventral parts 6 



6. Basal segment of clasper with a long 



spur almost as stout and long as 



mesal process, fig. 778 



erullus, p. 235 



Basal segment of clasper without such 

 a spur, at most with a large seta on 

 the mesal lobe, fig. 784 7 



7. Tenth tergite long, somewhat hooded, 



and with a pair of long, sclerotized 

 arms arising at its base and reach- 

 ing almost midway to apex, fig. 779 8 

 Tenth tergite either no longer than 

 cerci, fig. 791, or without such a 

 pair of arms, fig. 785 9 



8. Lateral arms of tenth tergite only half 



length of tergite; spine of aedeagus 



upturned at tip, fig. 779 



nephus, p. 230 



Lateral arms of tenth tergite more 

 than half length of tergite; spine of 

 aedeagus curved ventrad, figs. 780, 

 781 9 



9. Tenth tergite very long, with a sharp. 



hooded apex, fig. 780; aedeagus 



slender tarsi-punctatus, p. 



Tenth tergite shorter, as in fig. 781, 

 with a blunt and slightly enlarged 



apex; aedeagus robust 



alagmus, p. 



10. Claspers with body long and slender, 



with mesal process small, scarcely 

 longer than width of apical lobe, and 

 the body of the clasper with a mesal 

 lobe just under mesal process, figs. 



782, 783 



Claspers either with short body, fig. 

 790, longer mesal process, fig. 785, 

 or without a mesal lobe below mesal 

 process 



11. Base of clasper not produced into a 



spur, fig. 782, aedeagus small, with 

 the base narrow and with two in- 

 ternal spines dilutus, p. 



Base of clasper produced into a spur, 

 fig. 783, aedeagus large, with a 

 single internal spine and with the 



base greatly enlarged 



annulicornis, p. 



12. Claspers with apical segment bent at 



right angles to basal segment, fig. 



784 



Claspers with apical segment at most 

 slightly angled from basal segment, 

 fig. 786 



13. Mesal lobe of clasper with a fusiform, 



pointed spine, ng. 784 



angustus, p. 



Mesal lobe of clasper without a spine, 

 fig. 785 resurgens, p. 



14. Tenth tergite with a long neck and a 



long, somewhat hood-shaped head, 



fig. 786 ophioderus, p. 



Tenth tergite without a definite, long 

 neck and head, fig. 787 



15. Tenth tergite sickle shaped, the ven- 



tral margin evenly concave, fig. 787 



mentieus, p. 



Tenth tergite not at all sickle shaped, 

 fig. 788 



16. Sclerotized mesal process of clasper 



stout, fig. 788; front wings dark 

 brown, almost black, with a scatter- 

 ing of white scales 



-Sclerotized mesal process of clasper 

 slender, fig. 790; front wing medium 

 to light shades of brown without 

 scales 



17. Tenth tergite with narrowed apical 



portion nearly as long as base, cylin- 

 drical and rounded at apex, fig. 788 



punctatus, p. 



Tenth tergite with narrowed apical 

 portion short, tapering and truncate, 

 fig. 789 submacula, p. 



229 



229 



11 



12 



231 



232 



13 



14 



231 

 230 



232 

 15 



232 

 16 



17 



234 



235 



