356 CONXECTICUT GEOL. AND XAT. HIST. SURVEY [Bull. 



Type of subgenus. — Dicranota rivularls Osten Sacken (Eastern 

 Xeairtic). 



A weak division of the genus, paralleling Plectro77iyia in the 

 Rhaphidolahis group of species. The subgenus includes a few Euro- 

 pean species (loiu/ltar.sis Bergroth, robusta Lundstrom) and other 

 Nearctic forms (as eucera Osten Sacken and iowa Alexander). With- 

 in the group are found species with elongate antennae in $ and oth- 

 ers with the organ short in both sexes. 



Key to Species 

 (Based chiefly on male characters) 



1. Halteres pale; antennae short in both sexes, if bent backward ending some 



distance before wing-root ; male hypopygium with outer angle of basistyle 



produced into a lobe (Fig. 41, K) rivularis 



Halteres with knobs weakly to strongly inf uscated ; antennae ($) elongate, 

 if bent backward extending to some distance beyond base of abdomen ; male 

 hypopygium without lobe on basistyle (Fig. 41, G, I) 2 



2. Wings unmarked except for the pale brown stigma ; mesonotal praescutum 



with three brown stripes ; male hypopygium with inner dististyle elongate, 

 approximately twice the small oval outer style ; interbase with a long 



slender stem, the acute apex bent at a right angle (Fig. 41, I) eucera 



Wings with a brown seam on anterior cord, additional to the dark brown 

 stigma ; mesonotal praescutum with four brown stripes, the intermediate 

 pair approximated ; male hypopygium with both dististyles nearly equal in 

 length; interbase a short, powerful, beak-like blade (Fig. 41, G) iowa 



Dicranota (Paradic7'(mota) eucera O. S. (Figs. 40, F; 41,1). 



1861). Dicranota eucera Osten Sacken; Mon. Dipt. N. Amer., 4:281- 



282. 



Fig.— Dickinson, Cfls. Wise, p. 209, fig, 109 (wing) : 1932. 



General coloration of mesonotum gray; pleura gray. Antennae 

 dark throughout; in $ elongated, if bent backward extending about to 

 base of third abdominal segment, of 5 short, extending about to wing- 

 root. AVings with a weak brownish tinge, stigma darker; Rs short, 

 angulated at origin; cell ^3 short to very short petiolate. Abdomen 

 dark brown. Male hypopygium (Fig. 41,1). $. L. about 5-5.5 

 nun.; w. 6-7 mm.; antenna about 8 mm. $. L. 6-6.5 mm.; w. T-7.5 

 mm. 



(Apr., May) Mass., westw. to Minn., southw. to Md., Va. and N. C. Wisconsin 

 records (Dickinson, 1. c.) pertain to the next species (Rogers, in litt.). 



D. {Pamdicfanota) \oyf2t. X\qx. (P'ig, 41, G). 



1920. Dicranota ioira Alexander; Can. Ent., 52 : 78-79 ( $ ). 



1921. D. rogersi Alexander; lUd., 53 : 136 {$). 



Generally sinular to eucera in the elongate antennae of male. Male 

 hypopygium (Fig. 41, G). $. L. 5.5-6.5 mm. : w. 6-7.5 mm. 9. L. 

 7.5-8.5 mm. ; w. 8-10 mm. 



(June-Aug.) Que., westw. to Mich., Wise, Minn., and la., southw. to Hudsonian 

 Zone of Mt. Washington, N. H. 



