-35- 



45. Rt. clasper with a pro- 

 jection on mesal basal 

 area. 



fig. 152 



No mesal basal projection 



on rt. clasper. fig. 153 



tenuata Blickle & 

 Denning 1977 



stylata Ross 1938 



Oxyethira Eaton 1873 



As with most Hydroptilidae the distribution of the species in 

 the genus Oxyethira reflects, for the most part, the areas wherein 

 workers have been active. However, there does seem to be a general 

 pattern in that the species are more numerous east of the Missis- 

 sippi River and in the more northern regions of the area under con- 

 sideration. The numbers of species recorded from the northern areas 

 studied are: NH-IA, ME-14, MN-13, WI-10, IL-8, NY-7 , PQ-6; in the 

 south FL-11 and GA-6. This is not to say that any locality has been 

 covered completely, but some areas more extensively so than others. 

 In addition one species, Oxy . araya has been taken in the Yukon, 

 Canada and two, Oxy . obtatus and Oxy . sida , in Newfoundland. Some 

 species, such as Oxy . pallida , are quite widespread throughout the 

 area, and others as Oxy . aeola, Oxy . forcipita , Oxy . michiganensis 

 and Oxy . serrata occur across northern U.S.A. and southern Canada. 

 Oxy . dualis has been recorded from CA to NH and OR to NM but seems 

 to be restricted in breeding habitats. 



Four very similar species that may be difficult to separate 

 from each other occur from Florida northward to Canada to Califor- 

 nia as follows: Oxy . aeola Ross 1938, Oxy . abacatica Denning 1947, 

 Oxy . anabola Blickle 1966 and Oxy . barnstoni Harper 1976. The 

 first occurs from Oregon to British Columbia to Minnesota, the 2nd 

 in southeastern U.S.A., the 3rd from New Jersey to Canada and west 

 to Minnesota, the last one is known from Quebec. In the areas where 

 the species distribution overlaps they can be confused with each 

 other, however, when compared carefully as to genitalic characters 

 and structures of the other parts of the abdomen, differences be- 

 tween them are apparent. They are separated in the species key, 

 see completes 17 through 19, differences not in the key are: 8th 

 segment dorsally ; aeola - deeply irregularily emarginate, lateral 

 lobes with mesal shoulder; anabola - evenly emarginate, no mesal 

 shoulder; lateral ; aeola - lateral lobes sinuate on lower margin; 

 anabola - lower margin straight. In barnstoni the 8th tergum is 

 more weakly incised on the posterior margin, the 10th segment is 

 stouter and regularily rounded (lateral view) more so than in the 

 other species. 



