On the identity of Isoperla curtata (Plecoptera: Perlodidae): behavioural and molecular approaches show the existence of two separate species

Abstract

The identity of Isoperla curtata Navas, 1924, an Iberian endemics, has been questioned in the past since its description. In fact, there is a marked variability in pigmentation, wing length and in the penial armature within the species. Differences in the ecology of populations were also noted in previous studies: more orophilic in the Central-Northern part of the distribution area, and termhophilic in Sierra Morena (Southern Spain). In these studies it was underlined that it is difficult to arrange this polymorphism and divide I. curtata in subspecies or separate species. To clarify the real taxonomic status of I. curtata we combined a behavioural and a molecular approach on material collected in different streams from two different mountain systems of its distribution area, one in the Central-North and the other in the South Spain. We recorded and analyzed the mating call and we used a molecular marker, sequencing a fragment of the mithocondrial gene COI. Results of both approaches are in agreement and show a clear distinction of this taxon in two separate entities that deserve a specific status. The Central-Northern species corresponds to the nominal taxon, I. curtata, while the Sierra Morena populations (Southern Spain) belong to a new species, Isoperla morenica sp. n., hereafter described.