— Parameres not or but very shortly fused at bases (fig. 

 14:38m) 10 



4. Parameres fused 0.6 of distance to tip, free parts 

 pressed together halfway, abruptly narrowed to well- 

 separated fingerlike apices on distal 0.2; aedeagus 

 narrow, posterior margin with lateral teeth. . hurdi Wirth 



— Parameres fused less than halfway to tips 5 



5. Apices of parameres expanded, anterior margin of fused 

 part with deep mesal cleft 6 



— Apices of parameres tapering to filiform tips 7 



6. Apices of parameres blunt and greatly surpassing tip 

 of aedeagus caudad; anterior margin of fused part with 

 deep mesal cleft texana texana (Long) 



— Apices of parameres sharp, subequal to, and appressed 

 to, tip of aedeagus; anterior margin of fused part trun- 

 cate texana simulata Walley 



7. Fused part of parameres about 1/4 of total length 



8 



— Fused part of parameres 1/3 to 1/2 of total length . . 9 



8. Aedeagus with pair of low teeth on lateral margins; 

 fused part of parameres broader than long; dististyles 

 arcuate; 9th sternite with bilobate caudal margin . . . 



cilipes (Coquillett) 



— Aedeagus .v;ith lateral margins entire; fused part of 

 parameres longer than broad; dististyles sinuate; 9th 

 sternite rounded caudad quatei Wirth 



9. Aedeagus with apex pointed; fused part of parameres 

 about 1/3 of total length brevipennis (Macquart) 



— Aedeagus with rounded apex; fused part of parameres 

 about 1/2 of total length brookmani Wirth 



10. Parameres filiform on distal 1/3 or more 11 



— Parameres stout distad 13 



11. Parameres fused at base for distance about equal to 

 basal width 12 



— Parameres at least slightly separated at bases 



bipunctata (Linnaeus) 



12. Basistyles with distinct patch of dark spines on mesal 

 margin; aedeagus more than 1.2 times as long as broad 

 townesi Wirth 



— Basistyles without patch of spines on mesal margin; 

 aedeagus as broad as long squamipes (Coquillett) 



13. Parameres fused at bases 14 



— Parameres well separated at bases by about 1/4 their 

 total length, straight and rodlike, of uniform thickness 

 to tips; aedeagus more than 1.5 times as long as broad 



cinctipes (Coquillett) 



14. Parameres longer than basistyle; thickened from bases 

 to tips; aedeagus shield-shaped (fig. 14:38m) 



macswaini Wirth 



— Parameres about 0.75 times as long as basistyles, 

 rather heavy, but apices tapered; aedeagus heavily 

 sclerotized, with strong, expanded sublateral, caudal 

 lobes, deeply notched mesad both on fore and hind 

 margins occidentalis Wirth 



15. Parameres straight and clublike, with expanded caudal 

 apices; 9th tergite broadly rounded, reaching nearly to 

 apices of basistyles colemani Wirth 



— Parameres sinuate, sharp and incurved toward aedeagus 

 distad; 9th tergite short, not reaching more than 1/2 

 the length of basistyles monilicornis (Coquillett) 



16. Aedeagus about as long as broad, bell-shaped in out- 

 line, anterior basal arch extending more than halfway to 

 tip; dististyle slender, more than 5 times as long as 

 greatest breadth calcarata (Coquillett) 



— Aedeagus more than 1.5 times as broad as long, in 

 outline shaped like a derby hat, anterior arch shallow, 

 about 1/3 of total length; dististyle very broad, about 

 3 times as long as greatest breadth. . . var. sonora Wirth 



431 

 Wirth and Stone: Diptera 



Subfamily DASYHELEINAE 



Genus Dasyhelea Kciffer 



(Figs. U:ZSf,ff,t; 14:39n-0 



This genus is more aquatic than the preceding ones, 

 and favorite habitats include blanket algae of ponds 

 or slow streams, algae on dripping banks, and the 

 fermenting sap of tree ulcers. The larvae cannot 

 swim, but travel by crawling over the substrate and 

 will drown if submerged completely. 



Keys to the California Species of Dasyhelea 

 Females 



1. Posterior margins of abdominal tergites light yellow 

 2 



— Abdominal tergites uniformly dark 6 



2. Abdominal pleura with small black streaks 3 



— Abdominal pleura with large dark patches on segments 

 3-6 or all light 5 



3. Mesonotum with compact central tuft of long, scalelike 

 bristles; Kern, Imperial, and Riverside counties .... 



cincta (Coquillett) 1901 



— Mesonotum without central tuft of long, scalelike 

 bristles 4 



4. Anterior veins of wing brownish, intermediate antennal 

 segments elongate; Kern and Inyo counties 



brookmani Wirth 1952 



— Anterior veins of wing whitish, intermediate antennal 

 segments moniliform; Colorado River 



pallens Wirth 1952 



5. Mesonotum grayish-green pruinose with 3 contrasting 

 darker, narrow, longitudinal vittae; abdominal pleura 

 3-6 extensively black; southern and central California 

 grisea (Coquillett) 1901 



— Mesonotum uniformly brassy pollinose; abdominal 

 pleura uniformly pale; Imperial, Kern, and San Luis 

 Obispo counties pollinosa Wirth 1952 



6. Halteres with knobs entirely brown to black; mesonotum 

 velvety black; scutellum black; Modoc, Tulare, and San 

 Luis Obispo counties atrata Wirth 1952 



— Halteres with knobs yellow or white, at least above 



7 



7. Mesonotum shining 8 



— Mesonotum pruinose or quite dull 9 



8. Mesonotum extensively yellowish on sides and humeri; 

 3 broad, brown vittae in middle; Kern and Merced 

 counties ancora (Coquillett) 1902 



— Mesonotum uniformly black, humeri narrowly yellow; 

 southern California tristyla Wirth 1952 



9. Mesonotum extensively whitish or silvery pruinose; 

 pattern in lines or spots 10 



— Mesonotum dull or velvety black or both, with no 

 pruinose markings 13 



10. Humeri with large quadrate area yellow; silvery prui- 

 nose mesonotal pattern extensive; Imperial and River- 

 side counties f estiva Wirth 1952 



— Humeri black or very narrowly yellow 11 



11. Large species (more than 2 mm.); many long bristlelike 

 hairs; mesonotum with 3, narrow, longitudinal, setiger- 

 ous, pruinose gray vittae; Humboldt County 



tenebrosa (Coquillett) 1905 



