1st -stage larva is very similar in the different species); the larva of the 

 Hy porhy acophila type resembles this primitive stage but is larger. 



Branch 2 consists of 2 American groups with species, the larvae of which 

 are not known, and the European group "tristis," the species of which 

 (Rh. tristis and Rh. aquitanica) belong to the primitive type of the 

 group Hy po rhy a cophila like the species of branch 1. 



Branch 3 consists of 3 groups distributed in South Asia, Japan and North 

 America; only the larvae of the group "acropedes" are known, of the 

 North American species Rh. acropedes and of the Japanese species 

 Rh. articulata.* The larva of Th. acropedes and that of the Japanese - 

 Sakhalin species Rh. hokkaidensis, not included in the groups of Ross, 

 form the group Paleorhyacophila Lepn., described below; the larvae 

 of Rh. articulata belong to the type of the group Hy po r hy a c o p hi 1 a. 



Branch 6 consists of 9 groups, 3 of which are distributed in North 

 America, 3 in Asia, 1 in North America and Europe and 2 in Europe. The 

 larvae of the following North American groups are known: "carol in a" 

 (Rh. f ene str a, R h. 1 e d r a, Rh. kiamichi) and "invaria" (Rh. in- 

 var i a, R h. v i b o x, R h. n i g r i t a), and also of those of the middle - and 

 South Asian group "scissa" (Rh. ob s cu r a) and of the European groups: 

 "philopotamoide s" (Rh. h i r t i c o r n i s, Rh. p h i lo p o t am o i d e s and 

 Rh. pubescens) and "glareosa" (Rh. glareosa);** the larvae of the 

 preceding species belong to the primitive type of the group Hypo rhy a - 

 cophila Dohler. The larvae considered as the type of the group 

 Hypo rhy acophila differ also in other characters, such as form of head 

 and mandibles, and shape and length ratio of legs; they thus are subgroups of 

 the group Hyporhyacophila. The larvae of Rhyacophila obscura 

 of the group "sciss a" (branch 6) have a flattened head and strong forelegs 

 which are longer than the thin mid- and hind legs; similar forelegs are 

 characteristic for the larvae of the American species Rh. fenestra of the 

 group "carolina" and for the larva of Rhy a cophila sp. A (j a van a? ), 

 described by Ulmer (1957:140-141, Plate 12, Figures 34-35). 



Branch 7 includes the small Japanese-Chinese group "yosiiana" and 

 the large group "sibirica" with 26 species and 3 European species 

 (Rh. abchasica, Rh. laevis, Rh. product a), which are distributed in 

 North America, Japan, the Ussuri territory and Siberia. Larvae of 

 4 American species in the group "s ibi ri c a" are known; Rh. at rat a and 

 Rh. me lit a belong to the group Mesorhyacophila Lepn. (see p. 248) 

 according to the larvae; Rh. minora and Rh. manistee belong to group 

 Hyporhyacophila; to the same primitive group apparently belong the 

 larvae of the Asian species Rh. narvae and R h. s i b i r i c a, and probably 

 also Rh. depresse and Rh. lenae; of the European species of the group 

 "sibirica" the larvae of Rh. abchasica belong to the group Hyporhya- 

 cophila (see footnote on p. 136). 



The European species Rh. laevis has an isolated position in the group; 

 the larvae of this species have single abdominal gills. On the basis of this 

 and other characters, Dohler separated this species as the group Pros - 

 rhyacophila (this species was included in the group "sibirica" of Ross). 

 One may also place Rh. retracta of branch 9 in the group Prosrhyaco- 

 phila; the larvae of this species also have finger-shaped gills; however, they 

 are smaller than those of Rh. laevis and have a slightly different structure. 



* Rh. art iculat a Morton (syn. Rh. towadensis Iwata); see Ross, 1956:117; Fischer, 1960:73. 

 ** See: Dohler, 1950:250, 273, 289; Lepneva, 1961:652. 



134 



