248 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



Larva (pi. 41, fig. 387, and pi, 43, fig. 424). — (First description of 

 larva.) Total length, 6.6 mm. Head capsule i.i times longer than it 

 is wide. Width of thorax 1.4 times width of head. Abdominal seg- 

 ments 1-4 approximately 1.2 times width of head ; segments 5-7 some- 

 what expanded, widest at segment 6 which is 1.4 times average width 

 of segments 1-4; cross section of larva oval; in profile, appearing 

 similar to those of subgenus Dyarella. General color gray to tan, with- 

 out dark patches on ventrolateral regions of segments 6 and 7. 



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

 plate 41 , figure 387. Each cephalic fan with 44-45 pectinate branches, 

 the hairs on these branches simple, close together, rather long, inter- 

 spersed with slightly longer, heavier hairs at regular intervals. Man- 

 dible with 2 sharp-pointed teeth on its inner margin, both appearing 

 to emerge from the same base, the apical one longer. Antenna 370 ju, 

 long, 5-segmented, yellow, just passing the basal stalk of the cephalic 

 fan; segment i>2 = 3<4; segment 2 with superficial division at its 

 midregion ; segment i with longitudinal striations. Submentum with 

 9 apical teeth, the median one longer than the others, in shape like one 

 end of a hexagon ; ventrolateral row with 6-10 hairs in a straight line, 

 either trifid or with four branches ; lateral margin of submentum with 

 5 toothlike indentations. Occipital cleft triangular in shape (pi. 43, 

 fig. 424). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 39-44 

 rows of hooks at its apex ; postclypeal sclerites long, poorly sclerotized, 

 appearing to emerge from the posterior junction of the frons-clypeus 

 and the epicranial plates. Posterior sucker with 1 15-125 rows of hooks. 

 Anal gills with 3 principal branches, each with i large fingerlike pro- 

 jection and three shorter, more slender ones, giving a total of 12 

 branches in all. Anterior and posterior arms of X-shaped sclerite 

 long ; anterior arms well sclerotized only on basal half ; posterior arms 

 well sclerotized reaching the lateral margin of the larva ; well-sclero- 

 tized patch between the anterior and posterior arm of each side ; large 

 group of scales on either side between the anterior and posterior arms, 

 lateral to the patches; rectal scales present, bifid to 4-branched, in 

 irregular group. No ventral papillae or plaques on eighth segment. 



Types. — Pupae, in the collection of J. Romeo de Leon; collected 

 in streams above Totonicapan, and in the Rio Samala, Totonicapan, 

 Department of Totonicapan, Guatemala. Among the (^(^- and $5 

 used for the above descriptions, the following two have been desig- 

 nated as plesiotypes: Male (Accession Acat. 112-9) ; reared from 

 pupa collected in Rio Laguneta, Finca Tehuya, Acatenango, Depart- 

 ment of Chimaltenango, Guatemala, on April 2, 1948; collectors. 



