Trichoptera in finnish biogeographical provinces

Abstract

The sum of Trichoptera found in Finland is 208 species, after we here report both Crunoecia irrorata (Curtis, 1834) and Apatania stylata Navas, 1916 as new for the country. Out of the 21 biogeographical provinces there is now altogether 2520 finds, an increase of + 40.1% since the earlier paper dealing with the subject (Nybom 1960). Putting into a graph the latitude of the weighted geographical centre of a biogeographical province, and the sum of Trichopteran species found in it, and calculating a regression line, it comes up that in the north of Finland about 50 species less are found than in the south. In addition, when comparing the actual sums with this regression line, the three provinces with most incomplete investigation work are Al = Aland Islands, Oba = northern Ostrobothnia, southern part, and Ka = southern Karelia, in which the sum of finds are - 32%, - 21%, and - 19% below the regression line, respectively. Recently, the only determination key to Finnish caddisflies built up by the late J. Kyrki, Oulu University, was published in a book for fly fishers (Rinne et al. 1995).