92 



PSYCHE. 



DIPTERA FROM THE HEADWATERS OF THE GILA RIVER. —H. 



BY C. H. TYLER TOWNSEN'D, LAS CRUCES, N. MEX. 



TABANIDAE. 



Four 9 specimens of Tabanus (prob- 

 ably subgen. Therioplectes OS. )i from 

 the West Fork, show two distinct forms 

 easily separated by differences in the 

 antennae, front, and markings of the 

 abdomen. They look much alike, are 

 of the same size and have the same 

 general coloration. I have examined 

 descriptions of all the North American 

 species, but am unable to identify these 

 two forms with any of them. They 

 agree with each other in the following 

 characters, in most of which they ap- 

 proach T. rheinivardtii Wd. OS. 



Wings clear hyaline, without spots or 

 bands, costal cells clear except a yellow line 

 at stigma. First posterior cell open full 

 width. No stump at bend of anterior branch 

 of third vein, which bend is not angulate but 

 lounded. Eyes faintly but distinctly pubes- 

 cent. A slight ocellar tubercle, not or hardly- 

 denuded. Palpi stout, and rather broad 

 basally. Third antennal joint with a well de- 

 veloped process at base. Thin tuft of black 

 hair between base of wings and humerus. 



They differ particularly from T. 

 rheinwardtii (syn. erythrotelus 

 Walker. See Westwood's figure. 

 Dipt. Saund. pi. 2, fig. i) as follows: 

 Basal portion of third antennal joint 

 much shorter, and more widened, angle 

 more prominent. Abdomen grayish- 

 slate to blackish, not reddish on sides 

 or with hardly a tinge of red, no median 

 row of triangles. No clouds on wings. 



first posterior cell not at all coarctate. 

 They may be separated from each other 

 by the following descriptions. 



7. Tabanus gila7i2is\'\. i\i. Two 9 s. 

 West Fork Gila, July ro to 16. Taken 

 from horses. 



Length, 14 mm. Eyes (not revived) show 

 two dull green, oblique stripes on a cupre- 

 ous-brown background, running from innei 

 front angle of eye to outer upper border. 

 Front just perceptibly narrowed anteriorly, 

 parallel portion but little more than 2.i times 

 as long as vertical width. Callosity sub- 

 round, notched above, in one specimen con- 

 nected with the subcallus, in the other not. 

 Subcallus widened, longitudinally elongate, 

 in one case prolonged by a line above, in 

 the other deeply notched. A brownish tinge 

 on each side of subcallus and on vertex. Cal- 

 losities shining black. Front otherwise cin- 

 ereous pollinose, the portion next antennae 

 pale reddish and less pollinose. First anten- 

 nal joint widened apically, apical width equal 

 to length, but less than width of basal por- 

 tion of third joint. Second joint very short, 

 ending in a spur on upper edge. Basal 

 portion of third joint as wide as its whole 

 length, angle of process blunt; annulate 

 portion as long as basal, stout but last joint 

 elongate and tapered. First two joints red- 

 dish-yellow, third same color at base with 

 rest black. Palpi pale yellowish, white-hairy 

 with but few black hairs. Face, pectus, and 

 pleura white-hairy. Thorax and scutellum 

 whitish pollinose, with four heavy blackish 

 vittae on thorax rather <Jlosely approximated, 

 a slight reddish-yellow tinge apparent on 

 sides of thorax. Abdomen slate-color or 

 blackish, with a median longitudinal whitish 

 line widened on hind margins of segments. 



