2 (l). Length 3.5— 6.0 mm. Basal seta of mandibles short and spinelike, 

 much shorter than distal seta. Presegmental plates present on 

 abdominal segments 4—7, postsegmental plates on segment 4. Length 

 of pupal case 4— 8 mm 2. Agapetinae Mart. (p. 336) 



1. Subfamily GLOSSOSOMATINAE Ulmer 

 Key to Genera 

 Full-grown larva 



1 (2). Head and pronotum chestnut brown, without dots . 



1. Mystrophora Klap. (p. 323) 



2 (l). Head and pronotum yellowish brown or brown, with more or less 



distinct dots 2. Glossosoma Curt. (p. 333) 



1. Genus Mystrophora Klapalek 



Full-grown larva. Length 8—9 mm. Sclerotized areas chestnut brown, 

 without dots; dots visible only on the exuviae. Gula triangular, clearly 

 differentiated; pregula forming a narrow, transverse stripe; submentum 

 trapezoidal, with long anterior margin and short posterior margin. Prono- 

 tum with 3 oblique pale yellow dashes with setae at the sides. Meso- 

 and metanotum without tergites. The pleuron of prothorax small, that of 

 meso- and metathorax large. Legs thin; the three pairs differ little 

 in length. Anal claw massive, short, with ventral spinules. 



Pupa. Length 6—7 mm. Median seta of the 3 setae of the anterior 

 margin of the labrum, smaller than the other two. Basal tooth of mandible 

 small. Wing sheaths reaching abdominal segments 4—5. Presegmental 

 plates present on segments 3—7, postsegmental plates on segments 4—5. 

 End of body divided into two small lobes each with 3 setae. 



Pupal case built of sand grains and small stones. 



Mode of life and habitats. Mountain brooks, streams with rapids, 

 on stones. 



Distribution. USSR: northern part of the European USSR, southern 

 Siberia, Kamchatka and Far East. In addition, northern and Central 

 Europe, North America. 



The following species occur in the USSR: Mystrophora altaica 

 Mart. , M.ussurica Mart, and M. intermedia Klap. Only the larvae of 

 M. altaica Mart, are known. The larvae of M. intermedia were 

 briefly described by Kimmins (1943); he does not even describe the 

 coloration of the larva. It is not possible to give a key to the larvae of 

 My strophora. 



323 



