Variation of larval size and adult emergence period of Boyeria irene (Fonscolombe, 1838) (Odonata: Aeshnidae) in the Francia River of western Spain

Abstract Boyeria irene (Fonscolombe, 1838) is a large dragonfly common in rivers and streams in southern Europe, but it is little known about the biometrical variations of their populations. In this paper, we test whether the time of the emergence period of this species differs in the same river, whether the larval size varies during the emergence period, and whether the distinct size variations are associated with the different river sections. Results have revealed that 1) female exuviae are larger than those of males, 2) except for the paraproct length, the exuviae have similar size across the entire river length, 3) size of the exuviae is larger in the first period of emergence than in the second one. A difference in emergence duration across the three river sections has been recorded.