Association of adult female and male stoneflies (Plecoptera) from an Alpine river using wing morphometrics and mitochondrial DNA

The identification of stonefly (Plecoptera) species is often necessary in ecological studies and environmental assessments. Formal descriptions of many species are only available for adult males, making the identification of adult females problematic or impossible. We used morphometric analysis of seven species in five genera sampled from the Tagliamento River (Italy) to test whether field-caught females and males could be associated. Using 23 characteristics of the wing shape, Canonical Variant Analysis separated all seven species and clearly grouped males and females together in each species, despite some instances of small morphometric distance such as between species of Capnia Pictet, 1841. Three unknown females of Nemoura Latreille, 1796 were grouped with male N. cinerea (Retzius, 1783), and could thus be identified. Mitochondrial DNA (the DNA-barcoding region of the cox1 gene) supported the results, despite low genetic divergence between some congeners (e.g., 1% distance between species of Leuctra Stephens, 1836). Our results suggest that wing shape exhibits little variation between sexes in these species and that it may be a useful method of identifying adult females where only male descriptions are available.