366 



Leech and Chandler: Coleoptera 



Fig. 13:59. Psephenidae. a, Eubrianax edwardsi, larva, loft side, dorsal and right side, ventral 

 view; b, Ectopria sp., larva, ventral (a, Blackwelder, 1930; b, West, 1929). 



— Ninth abdominal segment with a ventral operculum 

 closing a caudal chamber containing 3 tufts of retrac- 

 tile filamentous gills (fig. 13:596), no other abdominal 

 gills; extensions of abdominal pleurae separated from 

 each other 3 



2. Eighth and 9th abdominal segments without lateral 

 expansions; gills on segments 1-6 or 2-6 



Psephenus Haldeman 1853 



— Eighth abdominal segment with lateral expansions 

 (fig. 13:59a); gills on segments 1-4 



Eubrianax Kiesenwetter 1874 



3. Ninth abdominal segment expanded, with hind margin 

 bilobed Acneus Horn 1880 



— Ninth abdominal segment quadrate (fig. 13:596), posterior 

 margin straight and little wider than anterior margin 

 Ectoparia LeConte 1853 



Key to Western Species of Psephenus 

 Adults " 



1. Head impression longitudinally divided; elytra pale 

 at base; common throughout California along streams 



haldemani Horn 1870 



— Head impression not longitudinally divided; elytra 

 uniform in coloration, except very narrowly on the 

 basal margin 2 



2. Pronotum velvety black 3 



— Pronotum dull and opaque, not velvety 4 



3. Pronotal sides evenly and feebly arcuate from base 

 to apex; pronotal punctures rather strong and dense 

 anteriorly, becoming finer and sparse behind; California 

 along streams veluticollis Casey 1893 



— Pronotal sides straight or feebly sinuate in middle two- 

 fourths, anteriorly arcuately continuous with the rounded 

 apical angles, apex arcuate; labrum impressed at 



"Based on Blaisdell's key (1923). It is possible that couplet 2 

 will prove to be a sexual character. 



middle; pronotal punctures scarcely recognizable 



(female); California along streams 



calaveraa Blaisdell 1923 



4. Pronotal sides bioadly rounded and sub parallel toward 

 base, more convergent and nearly straight anteriorly, 

 apex truncate; elytra with impressed lines, disc feebly 

 elevated along the suture (male); southern California 



along streams falli Casey 1893 



— Pronotal sides broadly arcuate, somewhat broadly 

 feebly sinuate at middle, apex arcuate; elytra without 

 impressed lines, not elevated along suture in male; 

 Idaho along streams lanei Blaisdell 1923 



Key to Western Species of Acneus Horn 

 Adults 



1. Elytra black, with 4 pale spots which do not reach the 

 elytral suture (fig. 13:580"); California, Oregon along 

 swift, rocky streams quadrimaculatus Horn 1880 



— Elytra predominantly pale with pale area reaching 

 suture, each elytron with 7 black spots; Oregon along 

 swift, rocky streams oregonensis Fender 1951 





REFERENCES 



BLAISDELL, F. E. 



1923. Two new species of Psephenus Hald., with a 

 note on N arpus angustus Casey. Ent. News, 34:234-238. 

 FENDER, K. M. 



1951. A new species of Acneus. Proc. Ent. Soc. Wash., 

 51:271-272. 



