Description of drumming signals of two species of Nemoura Latreille, 1796 from France (Plecoptera, Nemouridae)

The vibrational duets of Nemoura lacustris Pictet, 1865 and N. flexuosa Aubert, 1949 are described from France. Nemoura lacustris communicates with a two-way duet having an ancestral signal pattern in which both male and female exhibit monophasic signals. Nemoura lexuosa has a more complex signal in which the male grouped call is composed by 2-4 repeated groups characterised by an increasing mean number of beats within successive groups and decreasing intergroup intervals. The female answer is composed of a variable repetition of beats usually with the three first intervals and the last one longer than others. An uncommon characteristic of the N. flexuosa call is the existence of a second male signal (reply or response) in the absence of the female answer. This reply is similar to the female answer, probably mimicking it and acting as a mate guarding tactic as previously proposed for the replies in other stoneflies by Boumans and Johnsen in 2015, or it could act stimulating the answer of potential female mates, but this should be confirmed.