THE STREPTOCERA GROUP OF THE DIPTEROUS GENUS 



TIPULA LINNAEUS. 



W. G. DiEiz, M. D. 



A natural group of species, which briefly may be characterized 

 as follows: Wings approximately unicolorous, stigma distinct, 

 the antestigmal spot always extends into cell 1st M2, but is 

 interrupted in the outer end of cell R in most of the species. 

 The eighth sternite of the male is prolonged and narrowed 

 posteriorly, except devia. The hypopygium is of moderate 

 size. .The ninth tergite, generally small, is emarginate in the 

 middle, except fragmentata. The pleural suture is distinct, 

 except devia — the pleurite prolonged into a process, , generally 

 long and twisted, hornlike, rarely into an acutely pointed 

 cone, derbyi, or simply tipped by a sharp point, devia. The 

 ovipositor is very short, the upper valves generally rounded or 

 oval, in some species ending in a downward curved point, 

 giving thus a beaklike appearance; the lower valves scaphoidal. 

 In all the specimens in my collection, the posterior end of the 

 abdomen, especially the males, is curved upward and sometimes 

 backwards towards the abdominal tergum. Whether this 

 also obtains in the living insect I have no means to know. 



The species, below medium in size, are yellowish to testaceous 

 in color, with more or less lustre. They resemble each other 

 very closely and the genital structure of the males must in 

 almost all cases be depended upon for differentiation. 



KEY TO THE SPECIES. 



1. Joints of the antennal flagellum unicolorous. Western species 2 



Flagellar joints bicolored. Eastern United States; aberrant form. 



devia spec. n. 



2. The ninth tergite of the male distinctly emarginate 3 



Not as in the alternative fragmentata spec. n. 



3. The pleural process long, hornlike 4 



The pleurite prolonged into a pointed, conelike pvocass. .. .derbyi Doane 



4. The pleural process long, twisted, more or less curved, glabrous 5 



The process shorter, approximately straight, stiletto-like, hair\^, 



monocliroma Spencer 



5. Process conspicuously curved 6 



Process approximately straight trypetophora spec. n. 



6. The ninth tergite with a deep, oval emargination, the sides prolonged into 



converging processes, the inner margin with a conspicuous tooth. 



opisthocera spec, n 



Not as above 7 



7. Process shorter, viewed laterally, much wider in basal half. . .mutica spec. n. 

 Not as in the alternative 8 



8. Antennal flagellum — except basal joint — dark brown streptocera Doane 



Antennae entirely yellowish var. streptocera pallidocera var. n. 



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