Abdominal segment 1 with large dorsal process with rugose surface; 

 saddle-shaped median indentation at posterior margin shallow, lobes with 

 small black denticles (Figure 2 99) laterally. 



Lateral line from end of segments 5— 8, with dense, thin, brownish setae. 

 Holding apparatus with reddish brown plates; denticles black, numbers as 

 follows: 111:4; 1V:2; V: 3+ 16-17; VI:3-4; VII:3-4. 



Segment 9 strongly convex laterally, with 4 setae above each rod, 3 setae 

 large, thick, black, one (near median seta) small, light; ventral surface 

 with 4 short, thick, black setae. Anal rods long, narrower posteriorly, thick 

 at end, curved laterally; one of 4 small setae situated basally, thick, black, 

 2nd seta in about middle, light; other 2 setae large, black, situated subapically 

 behind each other; dark, but slightly smaller and thinner, seta near basal 

 seta. Sheath of male genitalia consisting of 4 lobes, lateral lobes larger, 

 the smaller lobes form the penis sheath (Figure 300 ). 



Pupal case more or less smooth, covered with interwoven plants and 

 with a thick, coarse membrane at ends; only 2—3 holes in membrane at 

 posterior end, divided by narrow bars. 



Mode of life and habitats. Detritophagous, phytophilous, in 

 snaall, sunlit water bodies, including ponds and lakes, marshy areas, in 

 vegetation of lakes and slow rivers, and in calm, detritus -rich biotopes 

 on open shore; common in ditches, small calm brooks, and near river 

 banks. 



D i s t r i but ion. European USSR, Western and Eastern Siberia, Altai, 

 Sayans, Middle Asia. In addition, Europe, North America. 



2. Limnophilus politus McLachlan 



Meyer, 1867:164-165.- Struck, 1900, Plate IV, Figure 31.- Ulmer, 

 1903:58.- Siltala, 1903a: 12-15, Figure 4, a-k; 1904c:49; 1907:498, 

 507-510.- Ulmer, 1909:259. Figure 389.- Lestage, 1921:729-732, 742, 748.- 

 Lepneva, 1940:212,215, Figure 159 h.- Hanna. 1956b: 139-144. 



Full-grown larva. Length 19—21 mm. Head pattern (Figure 301, A) 

 darker than in L. rhombicus; dark T-shaped figure on frontoclypeus wide 

 anteriorly, reaching frontal sutures laterally, with lighter brownish yellow 

 median area near anterior margin; this indentation is relatively deep in light 

 specimens and area near anterior frontal seta is less dark, so that the 

 darker part, which resembles head pattern of L. r ho mb i c u s, stands out 

 clearly against the lighter brownish background in these specimens; posterior 

 part of sclerite with large dots forming a wedge-shaped figure, and several 

 small dots on dark, uniformly wide stripe. Dorsal stripes dark, extending 

 from anterior to posterior margin, narrower posteriorly near coronal 

 suture; distinct black dots on stripes, and also lateral to them in posterior 

 part; lateral stripes also distinct, with rows of dark dots; a broad, dark 

 space between stripes behind eyes. Ventral surface of head mainly 

 brownish laterally, with groups of large dark dots, and with a light stripe 

 near anterior margin and along gular suture. Gula dark in its greater 

 part or entirely (Figure 301, b). 



Setae (Figure 30l)as in L. rhombicus. Labrum slightly darker 

 (Figure 302) than in L. rhombicus. Mandibles as in L. r ho mb i c u s. 



227 



