95 

 Day: Ephemeropteta 



Fig. 3:17. Male genitalia of Ephemerella spp. a, typical 

 nitalia of invaria group; b, typicol genitalia of needhami group; 

 typical genitalia of serrata group (Needham, Traver, and Hsu, 

 35). 



the penes deeper (fig. 3:176) needhami group 



. Penes broadened more at apex than at base; minute 

 papillae borne near apex on each side (fig. 3:166) 



simplex group 



Penes broadened as much or more at base than at apex; 

 no such minute papillae near apex; usually with barblike 

 lateral dorsal spines, 1 on each side (fig. 3:17c) .... 



serrata group 



Nymphs 



Gills present on abdominal segments 3-7 2 



Gills absent on segment 3, present on 4-7 5 



Teeth or spines generally present on the anterior margin 

 of fore femur; when absent, head tubercles present and 



spines of abdomen very large (fig. 3: 18a, b) 



walkeri (fuscata) group 



Teeth or spines wanting on anterior margin of the fore 



femur 3 



A whorl of spines at each tail joining; maxillary palp 



weak or wanting serrata group 



Tails fringed with long hairs in the apical part, may 

 have whorls of spines at the base; maxillary palp nor- 

 mally developed 4 



Rather long spines along the posterior margins of the 

 femora, and on the upper surface of the fore femur, 

 where they are arranged in an irregular transverse band 

 near apical end; (fig. 3:20c); tails without whorls of 

 spines at the base invaria group 



Fig. 3:19. Ephemerella nymphs, a, species of 

 b, tibialis; c, hecuba (a, Needham, Traver, and 

 Walley, 1930; c, Day). 



bicolor group; 

 Hsu, 1935; b, 



Fig. 3:18. Ephemerella sp ? of walkeri group, o, nymph; b, 

 ore leg of nymph showing spines on femur (Needham, Traver, 

 nd Hsu, 1935). 



— Only short and inconspicuous spines along the margins 

 of the femora; usually no spines on upper surface of 

 fore femur; but if present, generally distributed and not 

 in a transverse band; tails may have whorls of spines 

 in the basal half needhami group 



5. Knee spines present on all femora (fig. 3:19c) 



hecuba group 



— Knee spines absent 6 



6. Gill on segment 4 operculate; maxillary palp wanting; 

 segment 9 longer than segment 8 (fig. 3:19a) 



bicolor group 



— Gill on segment 4 usually semioperculate; maxillary 

 palp present; segment 9 not longer than segment 8 

 (fig. 3:20e) simplex group 



Genus Ephemerella Walsh: Serrata Group 



Key to the Colifornia Species 



Adults 



1. Ganglionic areas of sternites white or hyaline; dark, 



