91 

 Day: Ephemeroptero 



Fig. 3:13. a-h, male genitalia; a, Arneletus velox; b, A 

 herdi; c. Parol eptophlebia sp.; d, Siphlonurus speciabilis, 

 S. columbianus; i, S. occidentalis; g, Paraleptophlebia debi 

 h, P. pallipes; i, Choroterpes sp., anterior and posterior lame 

 of third gill and first gill; /', Paraleptophlebia sp., third nym 

 gill; k, Choroterpes sp., wings (a,b,d,e,f, Needham, Trover, 

 Hsu; c,i-k, Spieth, 1933; g,h, McDunnough, 1926). 



hep- 

 e, 



lis; 



lloe 

 phal 

 and 



up to 18 mm. They prefer quiet water and are often 

 found in warm, poorly aerated, detached pools. 6 



Key to the California Species 



Adults 



Hind wing of male often orange tinted; fore and hind 

 wings of both sexes with a large dark brown blotch in 

 the radial space (fig. 3:13d); widespread below 5,000 ft. 



elevation spectabilis Traver 1934 



Fore and hind wings of both sexes hyaline; prominent 

 dark U-shaped marks on abdominal sternites 2 



U-marks on .sternites 8 and !» diffuse fui'l poorlj defined; 

 a pale ruddy spot on the rear of the mesonoiurn <Uu. 

 3:13c); Sierra Ne\&d&. . . .colum'j ,,n,u , MoDunnougb 1936 

 U-marks clearly defined on sternites 8 and ft; no 

 ruddy mark on the mesonotum (fig, 3:18/); widespread 

 Occident all" Eaton 1885 



Key to the California Species 

 Nymphs, female 



1. Posterior margin of styliger plate with long, narrow 

 medial projection, sides of which are smoothly concave 

 from base to acute, pointed tip 



spectabilis Traver 1935 



— Posterior margin of styliger plate not as above 2 



2. Posterior margins of styliger plate with short, wide 

 medial projection, sides of which are straight and form 

 a right angle at tip occidentalis Eaton 1885 



— Posterior margin of styliger plate with low, rounded 

 medial projection columbianus McDunnough 1925 



Genus Edmundsius Day 



The genus Edmundsius was described from a single 

 species, Edmundsius agilis Day 1953. This genus 

 has been reported from California only, and both 

 nymph and adult resemble, in a general way, the 

 same life forms of the genus Siphlonurus. 



The nymphs of E. agilis have been taken in Madera 

 County on the western slope of the Sierra Nevada, at 

 elevations of from 5,000 to 8,000 feet. The species 

 frequent large, shallow, but well-aerated pools in a 

 typical small Sierra stream of high gradient. Nothing 

 is known of the adult life of this species except that 

 maturity is reached at the above locality during July 

 and early August. 



Adults. -~ The large male, about 16-17 mm. in length, has 

 wings with typical venation of the Siphlonurinae (fig. 3:2a). 

 Eyes contiguous, not divided, with lower part darker; 

 genitalia as in figure 3:27a. 



Nymph. — The gray brown nymph, up to 17 mm. in length, 

 is distinguished by long claws on the middle and hind 

 legs which are relatively twice as long as the claws of any 

 nymph of the closely related Siphlonurus. Tergites 2-8 dis- 

 tinctively marked with prominent white spots, one on each 

 side. Hind leg as in figure 3:27m. 



Genus Isonychia Eaton 



The genus Isonychia is represented in California by 

 but one species, /. velma Needham 1932. The nymph 

 has been found only in very fast riffles in the larger 

 rivers and streams of northern California and is a 

 large dark species up to 20 mm. in body length. 



Adults. — Forceps base of male and subanal plate of 

 female deeply excavated apically; venation strong, dark 

 brown (see fig. 3:2d for wing venation). 



Nymph. — Body darkest yellow-brown; head almost black; 

 tergites with faint, narrow pale median stripe in anterior 

 halves paralleled by a submedian pale stripe on each side. 



6 S. maria Mayo, 1939, is here regarded as a synonym of S. 7 This key is useful when applied to series of mature female 



spectabilis. nymphs. 



