94 



Day: Ephemeroptera 



Fig. 3:15. a, Ameletus amador, male genitalia; fa, Ephemerella 



hecuba, male genitalia; c, Paraleptophlebia he/ena, tusks on 



mandibles of nymphs (o, Mayo, 1939; fa, McDunnough, 1935; c, 

 Day, 1952). 



Known Nymphs 



Several of the California species of the genus Paralep- 

 tophlebia show considerable intraspecific variation 

 of size, color, and maculation. The following table is 

 given for its general value only. All species included 

 in the table possess lateral abdominal spines on 

 both segments 8 and 9. See figure 3:15c showing 

 tusks of the mandibles of P. helena. 



Genus Choroterpes Eaton 



The genus Choroterpes is represented in California 

 by but one species, C. terratoma Seeman 1927= The 

 nymph has been found in northern California only in 

 lotic, warm waters in small streams of the Coast 

 Range, north of San Francisco. The type locality is 

 in Los Angeles County. 



Male adult. — Small, about 6 to 7 mm, in length; gray brown 

 and blackish in general coloration, with sternite nine 

 entirely brown, and a dark ganglionic mark on eight; fore 

 wings hyaline with long veins dark brown except in anal 

 area; long, first joint of forceps bent strongly inward and 

 with bulbous process on inner margins near base (fig. 3:16a). 



Nymph. — Depressed in form; eyes of male nymph dorsal; 

 eyes of female nymph at dorsolateral margins of head; head 

 wide, flat, and relatively large. 



Subfamily EPHEMER ELLINAE 

 Genus Ephemerella Walsh 



Ephemerella is one of California's most common 

 genera, found in streams throughout the state. With 





Fig. 3:16. Male genitalia, a, Choroterpes terratoma; b, Epheme- 1 

 rella sp ?, typical genitalia of simplex group; c, Ephemerella 

 sp ?, typical genitalia of walkeri group; d, Ephemerella sp ?fl 

 typical genitalia of bi color group (a-c, Needham, Traver, and 

 Hsu, 1935; d, McDunnough, 1930). 



a few outstanding exceptions, the nymphs prefer 

 moderate currents and live on silt bottoms or among 

 trash and debris. However, some of California's 

 finest species are found in the granite-strewn torrents 

 of the Sierra Nevada, taking protection from the main 

 force of the water behind boulders, in crevices, and 

 in quiet situations near the edge of the stream. 



Key to the SPECIES GROUPS 

 Male Adults 



1. On pleural fold of segments 4-7, small fingerlike pro- 

 jections directed backward, those on 5-7 fully half as 

 long as their respective segments (fig. 3:156) 



hecuba group 



— No such projections along pleural fold 2 



2. Third joint of forceps at least twice as long as wide . 3 



— Third joint of forceps scarcely longer than wide 4 



3. Third joint of forceps 4 to 5 times as long as wide; 

 second joint not strongly bowed, but swollen basally, 

 slender apically; brownish species attenuata group 



— Third joint of forceps at least twice as long as wide; 

 second either strongly bowed or irregularly swollen; 

 blackish species (fig. 3:16c) . . . walkeri (fuscata) group 



4. Penes united, swollen basally, but not apically; no 

 spines present on penes; a distinct tubercle present 

 between them at the base (fig. 3:16d) bicolor group 



— Penes united, somewhat swollen apically; spines 

 usually present on penes; with or without a tubercle 

 between the bases of the penes 5 



5. Lateral apical margins of the penes projecting as dis- 

 tinct processes forward; usually several to many spines 

 on the penes 6 



— Lateral apical margins of the penes rounded, and with 

 no forward projecting processes; spines, if present, 

 barblike and dorsolateral in position 7 



6. Lateral apical processes of the penes short, blunt, and 

 directed inward; the apical notch between the penes 

 relatively shallow (fig. 3:17a) invaria group 



— Lateral apical processes of penes long and slender, 

 directed forward or outward; the apical notch between 



TABLE 3:1 

 Summary of Characters for Nymphs of Paraleptophlebia 





Head marked 



Tusks extended for- 



Lat. branchlets on 



Mid. abd. tergites 



Fore tibiae 



Nymphs 



with 



ward beyond head 



gill tracheae 



pale spotted 



marked with 



associata 



White spot 



None 



Short, fine 



Yes 



Unmarked 



cachea 



White areas 



None 



Very few 



No 



Unmarked 



calif ornica 



2 white spots 



None 



Sparse, fine 



Yes 



Dark area 



gregalis 



White spot 



None 



None 



Few 



Dark margin 



debilis 



Dark vertex 



None 



None 



Many 



Dark bands 



helena 



Black V 



Present 



None 



Strongly 



Brown spot 



placeri 



Pale spots 



None 



None 



Yes 



Dark bands 



quis quilia 



Dark brown 



None 



None 



Small 



Light brown 



pallipes 



Pale occiput 



None 



Yes 



Yes 



Unmarked 



2 ay ante 



Black wash 



Present 



None 



Yes 



Brown bands 



