moderately long. Section "b" of anal legs cylindrical and long; its inter- 

 mediate distal seta is the longest seta of the larva; this seta is almost as 

 long as the body in the 1st stage; the lateral seta of section "b" is as long 

 as intermediate seta in the 4th stage. Claw short, with thin and slightly 

 curved end; seta 7 is long, several times as long as the claw. Three caudal 

 tracheal gills. 



Pupa. Antennae of male pupae longer than those of female pupae. 

 Labrum slightly narrowed, with almost straight anterior margin and convex 

 posterior margin; two pairs of very short setae near the anterior margin; 

 2 short medial setae and 2 long lateral setae near the posterior margin. 

 Mandibles short, their basal seta straight; seta anterior to it curved. 

 Presegmental plates oblique, oblong; postsegmental plates skittle -shaped 

 and small. 



The pupal case is attached to the substrate by single attachment disks 

 connected by flaps of the case; the light color of the flaps contrasts with 

 the dark gray walls of the case. 



Mode of life and habitats. Stagnant and running water. 



Distribution. European USSR. In addition, Europe, Africa, southern 

 Asia, North America. 



1. Orthotrichia tetensii Kolbe 



Morton, 1887:202.- Klapalek, 1897:9-11, Figures 3-4.- Struck, 1900:29, 

 Plate 6, Figure 48, Figure 48. - Ulmer, 1903:134; 1909:225, 292, 

 Figure 351, a.- Siltala, 1904b:23-24. - Lestage, 1921:458-464.- Lepneva, 

 1940:202, -Nielsen, 1948:95-114, 138-139, Figures 2, B, 3, D, 4, D, 34-42, 

 51, D, 52, C, 63, Plate I, Figures 1-5. 



Full-grown larva. Length at the end of the stage 2.6—3.1 mm, width 

 of head 0.21—0.24 mm; ratio of length of head, thorax and abdomen at 

 beginning of 5th stage 10:15.5:18.5, at end of stage 10:16.5:77; abdomen not 

 laterally compressed, slightly flattened dorsoventrally (Figure 459). 

 Sclerotized parts brownish yellow, brown or darker in some places. Head 

 (Figure 460) without pattern, uniformly buff yellow, ovoid and narrower 

 anteriorly; in dorsal view head much lower anteriorly than posteriorly; 

 sutures clearly marked. Frontoclypeus relatively large, with long, broad, 

 anterior part; gula with slightly concave broad anterior margin. Sensilla 

 of antennae long (65 /u), its seta situated near the base, short and straight 

 (Figure 46l). Eyes displaced posteriorly, situated almost in midlength of 

 the head. The setae of the anterior part of the head differ from the normal 

 arrangement of the setae in Orthotrichia; only the lateral inward-curved 

 seta of the 3 anterior-margin setae of the frontoclypeus retains its position 

 near the anterior angle; the other 2 setae and seta 7 are displaced 

 posteriorly and are situated posterior to the antennae; the thin anterior 

 and posterior frontal setae are curved anteriorly and inward, recumbent; 

 setae 8 and 10 retain their position; setae 9 and 11 are both situated 

 posterior to the eye and the curvature of the frontal suture; seta 9 longer 

 and thicker than the others, setae 12, 14 and 15 of about the same length 

 (as long as the width of the head); seta 17 shorter than the above setae, 

 widely separated and directed upward and slightly anteriorly; ventral 

 seta 18 small but well marked. 



392 



