NO. I BLACK FLIES OF GUATEMALA — DALMAT III 



plate 40, figure 360. Each cephalic fan with 26-30 pectinate branches, 

 the hairs on these branches are simple, fine, rather long, and close 

 together, intermixed with longer, heavier simple hairs at regular inter- 

 vals. Mandible with 9-10 teeth along its inner margin ; when there are 

 10 teeth, the basal two teeth are close to each other but separated from 

 the rest ; the apical two teeth are well separated from each other as 

 well as from the middle group, the teeth of which are more or less 

 contiguous to one another ; none of the teeth are very well pointed or 

 markedly longer than the others. Antenna 290 [x long, 4-segmented, 

 reaching about three-fourths the way to the end of the basal stalk 

 of the cephalic fan ; segments i and 2 light brown, segment 3 much 

 darker and much thinner than segments i and 2 ; segment 3 almost 

 equal to length of segments i and 2 taken together; segment i with 

 longitudinal striations. Submentum with 17 apical teeth arranged in 

 groups of 3-3- 1 -3- 1 -3-3 as in aqumnarensis ; ventrolateral row with 5 

 hairs in straight line, the most-distal bifid along almost all its length, 

 the other hairs simple; most-basal hair minute; lateral margin of 

 submentum almost completely serrated, the toothlike processes not 

 very deeply cut. No occipital cleft (pi. 42, fig. 397). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 58-62 

 rows of hooks on its apex. Postclypeal sclerites very long and wide, 

 strongly tapered at inner extremity, not heavily sclerotized, with ir- 

 regular edges that appear to extend from point of junction of epi- 

 cranial plate and f rons-clypeus ; well separated, longer than in any 

 other Guatemalan species. Posterior sucker with 95-105 rows of 

 hooks. Anal gills composed of 3 simple digitate processes, each longer 

 than in aquamarensis, more rounded, and curving dorsally. Anterior 

 arms of X-shaped sclerite very heavily sclerotized, broadening an- 

 teriorly, with posteriorly directed spur from midregion ; no patch be- 

 tween arms ; posterior arms completely encircle the posterior sucker ; 

 with 4 to 5 rows of rectal scales that are bifid or trifid, and with sev- 

 eral trifid scales lateral to the expanded portion of the anterior arms. 

 Eighth segment with 2 well- formed, conical, ventral papillae; no 

 sclerotized plaques. 



Types. — (^, in collection of the Instituto de Salubridad y Enferme- 

 dades Tropicales, Mexico City ; collected in the Desierto de los Leones, 

 D. P., Mexico, at 3,200 meters above sea level, March 5, 1944. Para- 

 types, 7 J*(^ and 7 5$, in collection with type ^. 



