August, 1944 



Ross: Caddis Flies of Illinois 



93 



106 



100 



Apex of aedeagus with apico-lateral 

 corners of flange blunt, in profile 

 appearing to merge with apex of 

 dome, and narrow, as in fig. 383. . . 

 orris, p. 



28. Eighth tergite with ventral margin 



concave, the apico-lateral lobe bear- 

 ing a wide, compact brush of long 

 setae, fig. 3845; clasper receptacle 

 appearing deeply invaginated, large 

 and round, especially as seen from 



dorsal aspect, fig. 385 



betteni, p. 99; depravata, p. 



Either ventral margin of eighth tergite 

 with no apico-lateral lobe or only a 

 small brush, fig. 384^^, or clasper re- 

 ceptacle much smaller or more slen- 

 der, fig. 387 29 



29. Clasper groove not well-marked, clasp- 



er receptacle either not evident or 

 appearing from lateral view as only 

 a shallow crescent beneath dorsal 



cap, fig. 386^-D 



Either clasper groove well marked, 

 fig. 387//, or clasper receptacle rep- 

 resented by a definite pocket, fig. 

 3875-7, or by an invagination, fig. 



30 



Fig. 384. — Hydropsyche, lateral aspect of 

 female eighth tergite. J, bifida; B, betteni. 



DORSAL CAP 



CLASPER 



RECEPTACLE 



-ENTRANCE 



CHANNEL 



' CLASPER GROOVE 



POSTERO-LATERAL 



FLANGE 



LATERAL LOBE 



-APICAL TUFT 



.-.DORSAL CAP 



__. CLASPER 



RECEPTACLE 



"■POSTERO-LATERAL 

 FLANGE 



. LATERAL LOBE 



Fig. 385. — Hydropsyche betteni, female ter- 

 gites. Upper figure, lateral view including 

 tenth tergite; lower figure, dorsal view of ninth 

 tergite alone. 



3S6H-N, projecting beneath dorsal 

 cap 36 



30. Ninth tergite with lateral lobe not de- 



veloped; clasper groove small and 

 very shallow, scarcely any indenta- 

 tion visible beneath dorsal cap from 



dorsal view, fig. 386^^ 



dicantha, p. 102 



Ninth tergite with lateral lobe dis- 

 tinctly developed, either narrow, 

 fig. 386/C, or broad, fig. 386C; clasp- 

 er groove well-marked, larger and 

 forming a deep concavity visible 

 beneath dorsal cap from dorsal view 31 



31. Clasper groove with a small, distinct 



pit near dorsal margin, fig. 3865. . . 



placoda, p. 103 



Clasper groove without a pit 32 



32. Lateral lobes of eighth sternite with 



mesal and lateral margins parallel, 

 fig. 388C; head and thorax mostly 

 dark purplish brown, basal seg- 

 ments of antennae pale, with only 

 light V-marks, wings without irro- 



rate pattern cuanis, p. 100 



Lateral lobes of eighth sternite with 

 mesal margin sloping decidedly lat- 

 erad toward apex, fig. 388D; either 

 body much lighter, wings with irro- 

 rate wing pattern or basal segments 

 of antennae with very dark V-marks 33 



33. Lateral lobe of ninth tergite thick- 



ened at base, triangular in cross 



section, fig. 386D hageni, p. 103 



Lateral lobe of ninth tergite thin and 

 leaflike 34 



34. Clasper groove, from dorsal view, 



appearing wider and slightly angu- 



late at middle, fig. 386£ 



arinale, p. 104 



Clasper groove shallower and evenly 

 rounded, fig. 386F, G 35 



35. Clasper groove, from dorsal view, ap- 



pearing shallower, narrowing more 



rapidly anteriorly, fig. 386F 



phalerata, p. 102 



Clasper groove deeper, the anterior 

 portion wide, fig. 386G. . .aerata, p. 101 



36. Clasper groove forming a well-marked, 



curved trough, the upper end of 

 which projects only slightly under 



dorsal cap, fig. 387^ walkeri, p. 96 



Clasper groove either indistinct, fig. 

 3S6K, or running into a pocket-like 

 clasper receptacle, fig. 3875 37 



37. Clasper receptacle forming a wide tri- 



angular, crescentic or irregular 

 pocket which is not narrowed ven- 



trad, fig. 3S6H-N 38 



Clasper receptacle forming a pouch 

 with a narrow ventral opening, fig. 

 3875-/ 44 



