206 



Usinger: Hemiptera 



Five species of Belostoma have been recorded 

 from California but three of these, boscii L. & S., 

 fusciventre (Dufour), and apache Kirkaldy, remain 

 unverified. Fusciventre was described from Mexico, 

 and Mexican specimens which agree with the descrip* 

 tion have distinct interocular depressions and are 

 much darker than anything I have seen from California. 

 Apache was proposed as a new name for minor Dufour, 

 a Brazilian species, dubiously recorded also from 

 California by Kirkaldy (1908). Boscii appears also to 

 have been recorded first from California in the Kirk- 

 aldy-Bueno catalogue, though the early records and 

 misidentifications of Uhler (1870-1894) may have been 

 the source. 



Key to the Genera of Belostomatidae 

 Adults 



1. Basal segment of rostrum much thicker and shorter 

 than second; size large, more than 40 mm.; eggs not 

 laid on backs of males 2 



— Basal segment of rostrum not conspicuously thickened, 

 subequal to second segment; smaller, 36 mm. or less; 

 eggs laid on backs of males 3 



2. Anterior femora sulcate on inner face opposite tibiae 

 (fig. 7:17) Lethocerus Mayr 1852 



— Anterior femora not sulcate on inner face, one species, 

 B. griseus (Say, 1832), eastern United States . 



Benacus Stal 1861 



3. Membrane of hemelytra reduced (fig. 7:166); length 

 more than 27 mm.; except A. immaculatus (Say) from 

 Florida and Georgia Abedus Stal 1862 



— Membrane of hemelytra not reduced (fig. 7:16a); length 

 less than 22 mm Belostoma Latr. 1807 



Last Instar Nymphs 



Front legs with 2 equally developed claws 2 



Front legs with only 1 well-developed claw 3 



Front femora sulcate Lethocerus Mayr 



Front femora not sulcate Benacus Stal 



Inner anterior angles of eyes separated by a smooth 

 area and then indented in the form of a right angle with 



tapering anteocular part of head Abedus Stal 



Inner anterior angles of eyes continuous with gradually 

 tapering anteocular part of head Belostoma Latr. 



Key to California Species of Abedus 



Metaxyphus with a distinct median keel; western North 



America dilatatus (Say) 1832 



Metaxyphus elevated but not keeled 2 



Antennae 4-segmented, with prolongations from the 

 2nd and 3rd segments (=mayri De Carlo, 1948); Cali- 

 fornia, widely distributed (fig. 7: 166) ' 



hungerfordi De Carlo, 1932 



Antennae 3-segmented, with or without prolongations 



from the 2nd and 3rd segments 3 



Antennae without prolongations. Front tarsi with claws 

 as long as terminal tarsal segment; California?, Arizona, 



Mexico macronyx (Mayr) 1863 



Antenna with short prolongations from 2nd and 3rd 

 segments. Front tarsi with claws 3/4 or less the 

 length of terminal tarsal segment (=brachonyx Mayr); 

 California?, Arizona indentatus (Haldeman) 1853 



Key to California Species of Lethocerus 



1. Inner apical angle of under side of hind tibia produced 

 into a sharp point (fig. 7:18); interocular space dis- 

 tinctly narrower than width of an eye; Mexico and 



Saratoga Springs, Death Valley, California 



angustipes Mayr 1871 



- Inner apical angle of under side of hind tibia rounded; 



interocular space not narrower than width of an eye 



(fig. 7:17); widely distributed over the United States 



americanus Leidy 1847 



Key to California Species of Belostoma 



1. First rostral segment longer than second; vertex along 

 inner margins of eyes without conspicuous pubescence; 

 fore femora typically with 3 spots on outer and 3 spots 

 on inner surface (fig. 7:16a); Sacramento, San Joaquin, 

 and Imperial valleys flumineum Say 1832 



— First rostral segment shorter than second; vertex along 

 inner margins of eyes with conspicuous gray pubes- 

 cence; fore femora not spotted as above; widespread 

 bakeri Montd. 1913 



REFERENCES 



CUMMINGS, CARL 



1933. The giant water bugs. Bull. Univ. Kansas, 34:197- 

 219. 

 DeCARLO, J. A. 



1938. Los Belostomidos Americanos. An. Mus. Argent. 

 Cien. Nat. Buenos Aires, 39:189-252, Lam. I-VIII. 



Fig. 7:18. a, Lethocerus angustipes (Mayr), under side of hind 

 leg (Cummings, 1933); b, Abedus macronyx (Mayr), antenna; 

 c, A. dilatatus (Say), antenna; d, A. indentatus (Hold.), antenna; 

 e, A. hungerfordi De Carlo, antenna; f, A. indentatus (Hold.), 

 caudal filament; g, A. hungerfordi De Carlo, caudal filament; 

 h, A. dilatatus (Say), caudal filament (Hidalgo, 1935). 



