NO. I BLACK FLIES OF GUATEMALA — DALMAT I35 



1.4 times that of head. Width of first four abdominal segments 1.2 

 times width of head ; segments 5-7 expanded, greatest at segment 6 

 which is 1.6 times width of segments 1-4 ; cross section and profile the 

 same as that of other species in the subgenus Lanea. General color 

 yellow to tan, with greenish transverse bands around the abdominal 

 segments ; ventrolateral dark patches present on segment 7, at times 

 on segment 6 as well. 



Head: Designs on frons-clypeus and epicranial plates shown on 

 plate 40, figure 364. Each cephalic fan with 45-49 pectinate branches, 

 the hairs on these branches stout, bifid, well separated, not intermixed 

 with other types of hairs. Mandible with 2 short, triangular-shaped 

 teeth on its inner margin, the teeth close together but still separated 

 from each other ; more distal tooth just slightly larger than the other. 

 Antenna 390 fx long, 4-segmented, light yellow, just surpassing the 

 basal stalk of the cephalic fan; segment 3>2>i; base of antenna 

 rather long ; no transverse striations. Submentum with 9 apical teeth, 

 somewhat like a half of a hexagon in shape, the central tooth and the 

 outermost tooth on each side somewhat larger than the others ; ventro- 

 lateral row composed of 4 stout hairs in straight line, bifid or trifid 

 near the tips ; lateral margin of submentum with 7 well-formed tooth- 

 like serrations. Occipital cleft dome-shaped, the sides somewhat 

 parallel to one another (pi. 42, fig. 401). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 32 

 rows of spines at its apex ; postclypeal sclerites small, not very well 

 sclerotized. Posterior sucker with 63-65 rows of hooks. Anal gills 

 composed of 3 main divisions, each with 5-8 somewhat spatulate, 

 fingerlike processes arising close to one another, forming a handlike 

 structure ; each process bluntly rounded at tip. Anterior and posterior 

 arms of X-shaped sclerite well sclerotized; anterior arms each with 

 wedge-shaped expansion along the outer margin which almost reaches 

 the extremity of the arm ; expansions of both sides joined by a median 

 patch between the two anterior arms at the point where they join 

 with the posterior ones ; posterior arms extending almost to the lateral 

 margins ; no rectal scales. Two ventral papillae on segment 8, well 

 developed, somewhat pointed ; no sclerotized plaques. 



Types. — Holotype (c^), 4 slides, and allotype ($), 5 slides, in col- 

 lection of United States National Museum ; both collected from a 

 stream between Malacatan and Ayutla, Department of San Marcos, 

 Guatemala, July 18, 195 1. Paratypes, 5 c^c?, 4 $$, 19 pupae, and 16 

 larvae, in collection of the author. 



