INSECUTOR INSCITItE MENSTRUUS 41 



AN ACALYPTRATE GENUS OF MUSCOIDEA 



(Dipt era) 

 By CHARLES H. T. TOWNSEND 



Eucordylidexia, new genus. 



Genotype, Eucordylidexia ategulata Townsend, new species. 



This genus is remarkable for being practically a duplication 

 of Cordyligaster, except that both scales of the tegulse are 

 atrophied to a mere doubled rim. It is the only member of 

 the Muscoidea so far known with vestigial tegulae. The 

 petiole of the abdomen is more slender than that of Cordy- 

 ligaster septentrionalis and the wings are usually wholly and 

 deeply infuscate excepting only the glassy alula. The male 

 forceps and claspers are much more delicate in structure than 

 in that species. 



Eucordylidexia ategulata, new species. 



Length of body, 13 to 15 mm. ; of wing, 9.5 to 11 mm. Fif- 

 teen specimens, 2 from Guatemala (Deam and A. P. Cock- 

 erell), 6 from Costa Rica (Schild and Burgdorf), and 7 from 

 Panama (Busck and Jennings). 



The descriptions by Wiedemann, Brauer and Bergenstamm, 

 and Wulp of C. petiolata fit this species quite faithfully, and it 

 agrees quite perfectly with septentrionalis in color. There is 

 thus no necessity for color description. Comparison with 

 septentrionalis shows no appreciable structural differences out- 

 side of the tegulse and hypopygium. 



Holotype, No. 19219, U. S. Nat. Mus., female, Puerto Bar- 

 rios, Guatemala, February 24, 1905 (Chas. C. Deam). Allo- 

 type, male, San Carlos, Costa Rica (Schild and Burgdorf). 



It is taken for granted that petiolata, the genotype of Cordy- 

 ligaster, has well-developed tegulae, since none of the authors 

 just mentioned refers to this character and Wulp's figures all 

 show normal tegulse. One specimen from Acapulco (Baker), 

 which I determine as minuscula Wulp, and 35 specimens of 

 septentrionalis Townsend from District of Columbia all show 

 fully developed tegulse ; these two species are congeneric with 

 nyomala Townsend from Peru, which also has large tegulae. 



