fauna of Europe and the Caucasus of species with highly specialized larvae 

 of the groups Pararhyacophila, Hyperrhyacophila and 

 Rhyacophila s. str. These larvae have a flattened body, a highly 

 differentiated primary chaetotaxy, highly, but diversely developed thoracic 

 and abdominal gills and complex anal legs with hooklike and sword- shaped 

 processes. 



The small European species groups proposed by Ross ("tristis," 

 "philopotamoides" and probably "g 1 ar e o s a"), which consist of 

 1 to 3 species, have larvae of the primitive type Hyporhyacophila; they 

 were combined by Ross with the large American and Asian species groups; 

 they represent in Europe conservative groups of descendents of the ancient 

 immigrants from Asia; but although they remained isolated in Europe, they 

 retained a primitive type of larva like their Asian ancestors; according to 

 Ross, they also retained their common systematic position in branches 2 

 and 6 (which include large Asian-American and small European groups). 



A similar position in branch 1, which contains several Asian- American 

 groups and 1 European group, is taken by the group "stigmatica" 

 (Rh. stigmatica, Rh. meyeri, Rh. bonaparti); the larvae of this 

 group are of the Metarhyacophila type* which is closely related to 

 the primitive type Hyporhyacophila; however, it has fringed abdominal 

 gills and is convergent to the Asian larval type Paleorhyacophila. 



Thus, the classification of the Rhyacophila established by Ross on the 

 basis of imaginal characters proves on the whole correct (with several 

 exceptions) also as regards the relationships in the larvae (which are not 

 completely clarified). This classification thus is close to a natural 

 system of the R hy a c o ph i 1 a, reflecting its phylogeny and evolution. 



Flint and Wiggins revised some American groups (both adults and larvae) 

 Flint published articles on the larvae of the Nearctic species of the genera 

 Limnophilus and Arctopsyche; he also described the American 

 species of Rhyacophila which are used in the present book (Flint, 1960, 

 1961, 1962). Wiggins wrote a survey of the Nearctic species of B e r a e a, 

 established a new family (Phryganopsychidae) and described the larvae of 

 the American species of Phryganeidae (Wiggins, 1954, 1959, I960); he also 

 established the subfamily Yphrinae in the Phryganeidae; this subfamily 

 consists of a single, primitive species, Yphria californica Banks 

 (Wiggins, 1962).** 



The trend of work of Siltala was raised to a high level by Nielsen* (see 

 147 bibliography on pp.176, 193, 194). 



Nielsen began a study of oviposition, egg masses and the lst-stage larva 

 of 1 species in connection with his hydrobiological studies (Nielsen, 

 1936:255—266); Nielsen appreciated exact comparative morphological data 

 for the solution of biological problems and for the clarification of the 

 phylogeny of Trichoptera; he wrote as follows: "1st doch die Morphologie 

 die Lehre vom Werkzeug, die Biologie die Lehre von' seiner Anwendung] 

 Ferner wird eine solche Untersuchung zum Verstandnis der ganz unklaren 

 Frage der Phylogenie der Ordnung beitragen konnen und somit auf den 

 entwicklungsgeschichtlichen Zusammenhang der verschiedenenbiologischen 

 Typen Licht werfen" (Nielsen, 1942:257). 



* The larvae are described according to Dohler (1950); the author did not see larvae of the Metarhya - 

 cop hi la type. 

 "" : ' All the other genera of Phryganeidae belong to the subfamily Phryganeinae. 

 t Snodgrass, 1935. 



137 



