232 A. Lillehammer Fig. 29. Distribution of lsogenus nubecula New Fig. 31. Distribution of lsoperla grammatica mann. • The northernmost records in Sweden (Poda). and Finland. ''" I f ) ""'.:-b,;-. '..4.. ';~,,"'c.~,.-/" (t j; Fig. 32. Distribution of lsoperla obscura (Zetter stedt). Fig. 30. Distribution of lsoperla difformis (Klapalek).
Norwegian stoneflies II 233 forest areas, and in northern Norway it occurred also in the Sub-Alpine vegetation belt. In Sweden the species was taken both in the southern and northern parts, but mainly in southern streams (Brinck 1949). Isoperla grammatica (Fig. 31) is the most common of the Isoperla species. In the south it was taken both in coastal areas and at high altitudes (1100 m a.s.l.). It inhabits small streams, temporary or permanent, large streams and rivers. The species has not been taken in lakes. It does not occur above the Sub-Alpine belt, being common in the Boreal coniferous forest areas. In Sweden it was taken in all parts of the country (Brinck 1949). Isoperla obscura (Fig. 32) was taken in all parts of the country. In northern Norway the species has been found in small and large streams, rivers, lakes and lake outlets. In the coastal areas the species is rare. In southern Norway the species occurs in all types of freshwater in the central mountain areas where it was taken up to 1465 m a.s.l. It was seldom found in the lowlands where it is restricted to large streams and rivers, but it has been taken as far south as below 0yeren in the Glama watercourse, Akershus. In the west it is most common in the mountains, only occurring in large streams in the lowlands and then only in inner fjord areas. In some areas Isoperla obscura seems to occupy a wider spectra of habitats than elsewhere. These are the North 0sterdalen area, the mountain areas of 0vre Heimdal and the areas of Kautokeino and Pasvik. Isoperla obscura was taken both in northern and southern Sweden, but according to Brinck (1949) the species is eucoenic in northern rivers. Fam. Perlidae The carnivore Dinocras cephalotes (Fig. 33) was found in scattered localities from Telemark in the south to Finnmark in the north. Most of the records are from the central mountain areas of southern Norway where it was taken in small and medium-sized streams, largely in the Boreal pine forest zone, although it has also been taken in the Sub-Alpine belt (1090 m a.s.l. in 0vre Heimdal). In the west the species has been taken twice in Rogaland. In the north nymphs have been taken in Anajokka near Kautokeino. This is the northernmost record of this species. In Sweden Dinocras cephalotes was not taken in the northernmost parts and it has not hitherto been recorded from Finland. Fam. Chloroperlidae In this family there are only two species, both omnivorous. Xanthoperla apicalis (Fig. 34) has been taken at scattered localities in the boreal forest areas in southern Norway, once in northern Norway and not at all in western Norway. Siphonoperla burmeisteri (Fig. 35) occurs in all types of freshwaters in southern Norway in the boreal coniferous forest area up to the Sub-Alpine. In Sauda it was once found in the lowest part of the Sub-Alpine belt. The highest locality is at Mellsen in 0ystre Slidre at about 1000 m a.s.l. in the upper part of the coniferous forest belt. It is common in the west, including the coastal areas. In the north it has been taken in small and large streams, rivers and lakes in the pine forest area of Pasvik, where it is common. Outside this area it is more scarce. The species was taken both in northern and southern Sweden and is, according to Brinck (1949), eucoenic in northern streams. Fam. T aeniopterygidae In this family there are two species, both herbivorous. T aeniopteryx nebulosa (Fig. 36) has been taken in all parts of Norway, but is absent in the coastal lowland areas of North Rogaland and Vestfold. It occurs at all heights up to about 1200 m a.s.l. in the Low-Alpine belt. The species may be common and numerous both on stable stone substrata covered by moss and algae and in streams with a sand bottom and silting. It is found in all types of biotopes, except lakes, although it may be very common in outlets. The species has been taken both in northern and southern Sweden (Brinck 1949). Brachyptera risi (Fig. 37) has also been taken in all parts of Norway, but in Troms and Finnmark only in the fjord and coastal areas. In southern Norway it was taken in the outerm08t coastal areas of both North
Change language