A new troglobitic species of the genus Porrhomma (Araneae: Linyphiidae) from Bosnia and Herzegovina with taxonomic remarks on its relative Porrhomma egeria Simon, 1884

A new species of the spider genus Porrhomma from Bosnia and Herzegovina, P. ozrenense sp. nov. is described and illustrated based on male and female specimens collected from Mokra Megara cave in the area of Ozren Mountain. It is the first troglobitic Porrhomma species described from the Dinarides and the Balkan Peninsula in general. The main troglomorphic characters of the new species are extreme eye reduction, leg elongation, and noticeable depigmentation. A detailed description, photographs of the habitus and copulatory organs of the new species, and a distribution map are provided. Its relationship with other closely related species is discussed, especially in regard to the variability or taxonomic inconsistency of the European species P. egeria. The great faunal potential of the cave is emphasized and conservation measures are proposed to preserve its rich biodiversity.