NO. I BLACK FLIES OF GUATEMALA — DALMAT I7I 



apical spines instead of i. The genital rod of the same species has the 

 basal dilatation short, forming almost an equilateral triangle, while in 

 mathesoni the dilatation is more elongate and oval. 



The material used for comparison with acatenangoensis is the fol- 

 lowing : 



Sinnilium (DyarcUa) virgatum Coquillett: One male, one female, 

 and their cocoons collected in Hutto, Tex. These were lent to the 

 author by the U. S. National Museum at the request of Dr. Alan 

 Stone. Descriptions and drawings of Stone (1948). 



Simulium (Dyarella) rubicundulmn Knab : Several males, females, 

 and their cocoons collected on the Finca El Vergel, Chiapas, Mexico, 

 and given to the author by Dr. Luis Vargas. Also hundreds of speci- 

 mens collected in various parts of Guatemala and reared in the Oncho- 

 cerciasis Laboratory. Drawings of male and female genitalia by 

 Vargas (1942), 



Simulium {Dyarella) mathesoni Vargas: One male, one female, 

 and their cocoons collected in Gulatao, Oaxaca, Mexico, and given to 

 the author by Dr. Luis Vargas. Also several specimens collected in 

 Guatemala and reared in the Onchocerciasis Laboratory, some of 

 which were compared with the type by Dr. Vargas. Drawings of male 

 genitalia and cocoon by Vargas (1943). 



After studying the above material the author does not concur in the 

 synonymy of Stone (1948) in which rubicundulmn Knab and mathe- 

 soni Vargas are considered as being the same as virgatum Coquillett. 

 Each of these species, as well as acatenangoensis, is believed to be 

 distinct, the latter species being very close to mathesoni. In the same 

 paper by Stone, hippovorum Malloch is also considered a synonym 

 of virgatum Coquillett. 



Types. — Holotype (J*), 3 slides, and allotype (5), 4 slides, and 4 

 paratypes (2 (^(^, 2 $$) in collection of the United States National 

 Museum; holotype and allotype collected from the Rio Ladrillera, 

 Finca La Esperanza Perez, Acatenango, Department of Chimalte- 

 nango, Guatemala, November 25, 1948. Remaining paratypes (5 $$ 

 and 4 (^c^) in the collection of Herbert T. Dalmat. 



SIMULIUM (DYARELLA) ARDENI Dalmat 



Sintulium {Dyarella) ardent Dalmat, Ann. Ent. Soc. Amer., vol. 46, No. i, pp. 

 35-40, figs. 1-8, 1953 (original description, c?, 5, and pupa). 



Male (pi. 24, figs. 51A-51C). — 3.2 mm. long. 



Head: Holoptic. Upper half of each eye light brown, with dark 

 reddish-brown median patch ; lower half dark reddish brown. An- 

 tenna 730 II long, 1 1 -segmented, tapering ; segment 3 = 1+2, 3<4 + 5, 



