Fig. 4. Left: plots of maximum vertical pulling forces per body weight as achieved by representatives of 18 Stenus and one Dianous species on various surfaces (species-specific arithmetic means ± S.D.). Note the considerably higher pulling forces on filter paper (D). For sample sizes, see Table 2. Right: mean maximum vertical pulling forces as a function of the mean number of tarsal tenent setae, i.e. the number of tenent setae on one hind tarsus as reported in table 1 in Betz (2002). Before the analyses, both variables were corrected for body mass, as described in the text. (A) photographic paper, (B) glass slide, (C) dry Phragmites leaf, (D) filter paper. Red represents species with slender tarsi (subgenera Stenus s. str., Nestus), whereas green represents species with wide tarsi (subgenera Hypostenus, Metastenus and Hemistenus). Asterisks beside the coefficient of determination r² indicate different significant levels of the regression analysis: ^*P0.05; ^***P0.001. b, slope. 1, Stenus comma; 2, S. biguttatus; 3, S. fossulatus; 4, S. bimaculatus; 5, S. juno; 6, S. providus; 7, S. boops; 8, S. canaliculatus; 9, S. cicindeloides; 10, S. solutus; 11, S. similis; 12, S. tarsalis; 13, S. latifrons; 14, S. bifoveolatus; 15, S. binotatus; 16, S. pubescens; 17, S. nitidiusculus; 18, S. impressus; 19, Dianous coerulescens.