August, 1944 



Ross: Caddis Flies of Illinois 



55 



Acrocentropus Betten (1934, p. 213). Geno- 

 type, monobasic: Polycentropus Incidns Hagen. 



Only one species of this genus has been 

 taken in the state. A second species, lucidus, 

 occurs in the northeastern states and may 

 eventually be found in Illinois. We have 

 not reared this genus in Illinois, but descrip- 

 tions of the larvae by Vorhies (1909) and 

 others indicate characters for a clear-cut 

 generic diagnosis. 



KEY TO SPECIES 

 Adults 



1. Apex of abdomen with dorsal and 



ventral appendages, figs. 218, 219 



(males) 2 



Apex of abdomen conical with a pair 

 of flaplike ventral appendages, figs. 

 220, 221 (females) 3 



2. Tenth tergite sclerotized and pro- 



duced into a heavy, upturned hook; 

 apex of aedeagus sharp, fig. 218. .. . 



lucidus, p. 56 



Tenth tergite broad and truncate, not 

 sclerotized; aedeagus tubular with 

 the apex obliquely truncate, fig. 219 

 placidus, p. 55 



\Xli/^^ 



219 

 A 



PLACIDUS 



Figs. 218-219. — Phylocentropus, male gen- 

 italia, /i, lateral aspect; B, claspers, caudo- 

 ventral aspect. 



Figs. 220-221. — Phylocentropus, female gen- 

 italia. 



3. Apex of eighth sternite broad, the mes- 

 al incision forming 2 wide lobes, fig. 



220 lucidus, p. 56 



Apex of eighth sternite narrowed and 

 divided into 2 small lobes, fig. 221 . . 

 placidus, p. 55 



Phylocentropus placidus (Banks) 



Holocentropus placidus Banks (1905/^, p. 15); 



Phylocentropus maximus Vorhies (1909, p. 

 711); d^, larva and pupa. 



Larva (after Vorhies). — Length 15-16 

 mm. Head, pronotum and legs straw yel- 

 low, pronotum with posterior half of lateral 

 border and all posterior border black; body 

 colorless. Labium elongate and styliform. 

 Mandibles short and stocky, dorsal surface 

 with more or less granular teeth and mesal 

 portion provided with a dense large brush. 



Adults. — Length 9-1 1 mm. Color vari- 

 ous shades of brown ; wings finely and al- 

 most evenly speckled with light brown. 

 Front wings with Rg angled near base and 

 touching stem of M. Male genitalia, fig. 

 219: cerci ovate, tenth tergite wide, un- 

 sclerotized and almost truncate at apex ; 

 claspers appearing ovate from side view, 

 ventral aspect more or less quadrate with 

 a dense brush of black setae along mesal 

 margin; aedeagus tubular, the apex oblique- 

 ly truncate. Female genitalia, fig. 221 : 

 eighth sternite tapered at apex and incised 

 to form a pair of small lobes. 



Our Illinois records of this species are 

 from two southern localities in the Ozark 

 Hills. The account of its biology is given 

 by Vorhies, who found it making tubular 



