24 SOUTH AMERICAN TIPULIDAE 



diverge from Rz is apparent. The genitalia of the male 

 sex shows several distinct lines of specialization. The general- 

 ized jivaro and exilis have the ninth tergite large, subquadrate, 

 with a broad and deep median furrow; the ninth pleurite is 

 extensive, the eighth sternite very small but with a conspicuous 

 median tripartite organ. As evolution proceeds we find the 

 broad furrow on the ninth tergite narrowed to a delicate impressed 

 line, the ninth pleurite becoming small, oval or elongate-oval, 

 situated on the caudal face of the ninth sternite and the eighth 

 sternite with the median lobe single and finally becoming re- 

 duced to a mere tuft of hairs. The order of specialization in 

 the forms known to me seems to be about as follows: 



1. More generalized with shortened antennae and generalized 

 hypopygium, — jivaro, exilis and possibly other species described 

 by earlier workers, l^ut from their insufficient descriptions not 

 definitely recognized. 



2. No representatives of the intermediate group are known to 

 me. 



3. With the antennae elongated but still much shorter than the 

 body, — 7nitua, ornaticornis V. d. W., carizona Alex. 



4. Highly specialized species with the antennae only a little 

 shorter than the entire body, — monilijera Loew, moniliformis 

 Rod., armillatus. Of uncertain position, known only from 

 the female sex, — quichua sp. n. 



The body color-pattern is curious and is indicated in all of the 

 species. The insects show a more or less distinct, very narrow, 

 dorso-median vitta running from the head over the entire length 

 of the thorax; on the ground color between the usual thoracic 

 stripes occur rather abundant hair-like setae and each of the 

 setigerous punctures is surrounded by a ])rown circle, producing 

 a spotted appearance. 



Tipula exilis sp. n. 



Monilijera group; antennae short in both sexes; head and thorax dark gray; 

 a narrow dorso-median Une running the length of the thorax; wings mottled 

 white, brown and gray; abdomen of the female very long and slender. 



Male. — Length, 12 to 15 mm.; wing, 12.1 to 14.1 mm.; abdomen, 11.6 mm. 



Female. — Length, 24 to 26 mm.; wing, 1.5.2 to 15.5 mm.; abdomen, 19 to 

 21.5 mm. 



Frontal i)rolongati()n of the head modrrately long, brown, a littlo darker 

 on the sides of the organ; palpi nioderatcly long, dark brown. Antennae 

 rather short (sec plate IV, fig. 5), a little longer than in T. jivaro which is very 



