Potamophylax rilaensis sp. nov. (Trichoptera: Limnephilidae), a new species of the Potamophylax winneguthi Species Cluster from Bulgaria

The Potamophylax winneguthi Species Cluster is recognized for its high diversity and microscale distribution across Kosovo, Serbia, Bulgaria, and Bosnia and Herzegovina. In this paper, we describe Potamophylax rilaensis sp. nov., a new species within this cluster from Bulgaria, which is morphologically most similar to P. juliani Kumanski 1999 (in Kumanski & Malicky 1999) and P. kosovaensis Ibrahimi & Bilalli 2024 (in Ibrahimi et al. 2024).

The males of P. rilaensis sp. nov. differ from closest congeners by distinct morphological features, particularly in the shape of the inferior appendages, parameres, and paramere spine pattern. Potamophylax rilaensis sp. nov. was found at two localities in the Rila Mountains, at elevations ranging from 1462 to 1935 m above sea level. With the addition of P. rilaensis sp. nov., there are now eight known species within the P. winneguthi Species Cluster identified from the Balkan Peninsula.

A comprehensive overview of species distribution, habitat preferences, and diagnostic features of male genitalia is also provided.