Studies of North American Bees 35 



Stelis (Microstelis) arizonensis n. sp. 



$. Length 7-8 mm. Black; broad lateral face marks contiguous to an- 

 terior orbital margins, sometimes two small spots on clypeus, a short, broad 

 line behind ocelli, L-shaped marks margining the lateral and latero-anterior 

 margins of mesoscutum, axillar spots scarcely separated from a broad and 

 continuous line bordering mesoscutellum posteriorly, small spots on tu- 

 bercles and usually under hind wings, and uninterrupted broad bands on 

 the middle of tergites 1-5, chrome yellow. The bands on tergites i and 2 

 have linear spots laterally near the posterior margin which sometimes 

 break through to form squarish emarginations, while that on 2 is more 

 narrowed medially than the others, though not interrupted, and that on 5 

 is usually squarely, shallowly emarginate laterally on the anterior margin 

 and also medially notched. Tegulae yellowish or reddish, with a dusky 

 central hne. Legs usually red, with small yellow spots on the knees ; the 

 coxae, sometimes the trochanters and femora behind and beneath and a 

 spot on outer face of the tibiae usually more or less black, this latter color 

 sometimes involving most of the legs, leaving only the femora above, the 

 ends and inner sides of the tibiae and the basal tarsal joints red. Wings 

 infuscated along costal margin as in S. costalis Cress., the second recur- 

 rent nervure received beyond the second transverse cubital nervure. Sculp- 

 ture and pubescence essentially as in 5". costalis. 



S- Length 6-7.5 mm. Colored like the 5, except that the clypeal spots 

 are usually present and are sometimes enlarged to form a broad, superiorly 

 trilobate band, the legs are usually darker, sometimes black with the ends 

 of the femora and the basitarsi red and the knees with yellow spots, and 

 tergite 6 usually has an apical yellow band or two yellow spots. The 

 pleura may be wholly black or may have one to three small yellow spots. 

 Second recurrent nervure usually interstital with second transverse cubital 

 nervure though sometimes slightly beyond it, this being a variable character 

 apparently partially associated with the sex. 



Type. — Southern Arizona, August 1902 (F. H. Snow), 5- 



Allotype. — Type lot, i J'. 



Paratypes. — Type lot, i $, 2 J*; Oak Creek canyon, Arizona, 

 6,000 feet, July (F. H. Snow), i J*; do., August, 5 J*; Santa 

 Rita Mountains, Arizona, 5-8,000 feet, July (F. H. Snow), i (^. 



The paratype male from the Santa Rita Mountains is aberrant, 

 differing from the other nine males in its almost wholly black 

 legs, black tubercles, black sixth tergite and its anteriorly laterally 

 emarginate bands on tergites 4 and 5. 



This species is obviously very closely related to S. costalis 

 Cresson, from Texas, but differs at once in both sexes by the 



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