104 



Day: Ephemeroptera 



TABLE 3:2 

 Summary of Characters for Adults of the Genus Baetis 





Wing length, 

 mm. O 



Turbinate 



Veins In 



Costal projection of 



Abdominal tergites. 



Speoles 



eye, o 



hind wing 



hind wing 



e?3-6 



adonis 



5 



Large 



3 



Acute 



Yellow brown 



alius 



5'/ 2 



Moderate 



3 



Acute 



Hyaline brown 



bicaudatus 



6!4 



Small 



2 



Acute 



Hyaline brown 



devinctus 



5 



Moderate 



3 



Acute 



Whitish 



diablus 



8 



Med. large 



3 



Acute 



Yellow brown 



insignificans 



4 



Small 



2 



Absent 



Pale 



intermedins 



m 



Large 



3 



Acute 



Light brown 



leechi 



4 



Moderate 



3 



Curved 



Brownish yellow 



piscatoris 



6 



Moderate 



3 



Acute 



Yellow white 



sulfur os us 



4 



Moderate 



3 



Weak 



Smoky brown 



thermophilos 



5 



? 



3 



Weak 



Olive brown 



tricaudatus 



7 



Moderate 



3 



Acute 



Hyaline 



palisadi 



8 



Large 



3 



Acute 



Hyaline 



veins 2 and 3 (fig. 3:25c); Truckee and Feather rivers 



intermedins Dodds 1923 



— Vein 3 of hind wing stronger; often a faint intercalary 

 between veins 1 and 2 of hind wing, and usually faint 

 traces of 2 intercalates between veins 2 and 3; Santa 

 Cruz and Napa counties piscatoris Traver 1935 



Only five nymphs of California Baetis have been 

 associated with the adults, these being: 



B. alius Day 

 B. bicaudatus Dodds 

 B. intermedins Dodds 

 B. piscatoris Traver 

 B. tricaudatus Dodds 



The labial palp of the nymph of Baetis is three- 

 jointed, the distal joint being short and rounded as in 

 figure 3:26A. 



Genus Centroptilum Eaton 



Scattered collections indicate this genus is probably 

 generally distributed throughout California; the nymph 

 is a free-ranging, open water form. 



Key to the California Species 

 Male Adults 



1. Mesothorax olive brown or black 2 



— Mesothorax red brown or brown 3 



2. Head and thorax olivaceous brown; abdominal tergites 

 2-6 yellowish tinged with brown; third joint of forceps 

 not strongly bowed, but widened apically (fig. 3:26rf,A); 

 San Bernardino Mts., Santa Cruz and Napa counties 



asperatum Traver 1935 



— Head and thorax shiny black; abdominal tergites 2-6 

 hyaline white; third joint of forceps distinctly bowed 

 (fig. 3:26c, l); Santa Cruz County 



conturbatum McDunnough 1929 



3. Hind wing long and narrow, about 6 times as long as 

 broad, with two longitudinal veins but no intercalates 

 or cross veins; abdominal tergites 2-6 hyaline white, 

 sometimes faintly pink tinged (fig. 3:26m); Sonoma and 

 Contra Costa counties convexum Ide 1930 



— Hind wing broader than above, about 4 times as long 

 as broad, with a distinct intercalary below the second 

 of the two longitudinal veins, and 7 to 1 1 distinct cross 

 veins present; abdominal tergites 2-6 yellowish white, 

 semitranslucent, with posterior margins and lateral 

 areas reddish or orange brown (fig. 3:26/,n); San Gabriel 

 Mts venosum Traver 1935 



But one nymph of the above species is known, 

 namely that of C. convexum Ide. Gills are single on 

 all segments; the thorax is pale with restricted brown 

 markings; abdominal tergites three to five are brown 

 with pale median areas; and there is a dark band 

 across the tails just beyond the middle. 



The labial palp of Centroptilum is three-jointed, the 

 distal joint dilated and roundly truncate apically as 

 in figure 3:26e. 



Genus Apobaetis Day 



Apobaetis is known from the type species A. inde- 

 prensus Day, taken only from the lower Tuolumne 

 River, California. The male adults have wings about 

 4 mm. in length and cannot be separated from either 

 Pseudocloeon or Paracloeodes; the nymphs of the 

 three genera may be separated by the form of the 

 labium as figured herein (fig. 3:28c). The nymph of 

 A. indeprensus is unique in the entire subfamily 

 Baetinae in having a straight, unmodified frontal 

 margin of the labrum. 



Genus Paracloeodes Day 



The type species of the genus, P. abditus Day, has 

 been taken only from the lower Tuolumne River, 

 California. The second species of the genus, P. 

 portoricensis from Puerto Rico, was set up by removal 

 from the genus Cloeodes. The male adults of P. 

 abditus have wings about 3% mm. in length and cannot 

 be separated from either Pseudocloeon or Apobaetis; 

 the nymphs of the three genera may be separated by 

 the form of the labium as figured herein (fig. 3:286). 



Subfamily AMETROPINAE 



In the Nearctic this subfamily consists of two genera, 

 Ametropus Albarda and Metreturus Burks. Neither 

 genus is represented in California. 



The adult of Ametropus is characterized by the fore 

 tarsus of male adults being very long in proportion 

 to the short tibia, and by claws dissimilar on all 



