86 



Day: Ephemeroptera 



Fig. 3:6. a,b, anterior and posterior lamellae of third nymphal gill of Heplagenia sp.; c, H. 

 kennedyi, male genitalia; d, H. e/eganfu/a, male genitalia; e, H. rubroventris, male genitalia 

 (a,b, Spieth, 1933; c-e, Needham, Traver and Hsu, 1935). 



Genus Heptagenia Walsh 



Distribution is general in smaller streams throughout 

 California from the seacoast to the eastern slopes of 

 the Sierra Nevada. 



Key to the California Species 

 Male Adults 



1. Veins of fore and hind wings entirely colorless; legs 

 pale, fore femora and tibiae tinged with black at apices; 

 tergites 2-9 pale, faintly smoky along posterior margins 

 (fig. 3:6c) (Alameda and Napa counties) 



kennedyi McDunnough 1924 



— Long veins of fore wing dark; fore legs not as above 



2 



2. Subcosta and radius of fore wing amber in basal half; 

 all other veins fine, blackish; fore leg light brown, 

 femur banded at middle and darkened at apex; tergites 

 2-7 pale hyaline, posterior margins smoky; 8-10 tinged 

 with pink (fig. 3:6d) (San Joaquin Valley) 



elegantula (Eaton) 1885 



— Long veins fine, dark brown; cross veins entirely- 

 colorless; fore femur dark ruddy with apex narrowly 

 black; fore tibia pale basally, ruddy apically; abdomen 

 widely marked with dark red (fig. 3:6e) (widespread) 



rubroventris Traver 1935 



lateral abdominal spines on segments 6, 7, and 8 absent 



elegantula (Eaton) 1885 



Pronotum widest at middle; claws pectinate, postero- 

 lateral abdominal spines present on segments 6, 7, and 

 8 rubroventris Traver 1935 



Genus Cinygma Eaton 



The single representative of this genus in California 

 is herewith designated as C. sp? This species is 

 quite close to C. dimicki McDunnough but the male 

 may be separated from the latter species by its wide 

 black bands across the posterior margins of the ster- 

 nites. The nymph has comparatively much smaller 

 gills on segment 1 than have been found in other 

 nymphs of this genus. Cinygma is found in the lower 

 Sierra Nevada from 5,000 to 7,000 feet in moderately 

 fast water, nearly always clinging to wood and bark 

 of dark color. 



Although flattened and apparently well adapted for 

 swift water habitation, the two following nymphs 

 prefer slow moving currents. They are found under 

 rocks in midstream or in rocky situations at the 

 water's edge. 



Known nymphs 



— Pronotum widest at front; claws not pectinate; postero- 



Fig. 3:7. Male genitalia of Rhithrogena. a, flavianula; b, doddsi 

 (a, Day, 1954; b, McDunnough, 1934). 



Genus Rhithrogena Eaton 



With the exception of three species, this genus has 

 been found in California only above 6,000 feet in the 

 Sierra Nevada. R. petulans may extend its range from 

 southern California into the redwood belt of northern 

 California. R. morrisoni has been found on both sides 

 of the Sierra Nevada, and an undescribed related 

 species occurs in the Redwood Belt and Coast Range. 

 The nymphs are limpetlike forms with expanded gills 

 forming perfect suction cups for attachment to stones 

 in fast currents. 



Key to the California Species 

 Male Adults 



1. Fore wing 8 mm. or less in length (fig. 3:276); Shasta 

 County decora Day 1954 



— Fore wing 10 mm. or longer 2 



2. Lateral spine near base of each long, slender division 

 of penes, 5 or 6 dorsal spines in central part of each 

 division; larger species, wing 15 mm. in length (fig. 

 3:7a); Alpine County . . . flavianula (McDunnough) 1924 



— Basal lateral spines of penes as above; ventral spines 

 present on each division of penes in central part; wing 

 13 mm. or less in length 3 



