A new species of Speleophriopsis (Copepoda: Misophrioida) from an anchialine cave in the Adriatic Sea, Mediterranean

Abstract

A new copepod species, Speleophriopsis mljetensis, collected from an anchialine cave Bjejajka on Mljet Island (Croatia) is described. The prosome of the new species is 5-segmented; the urosome has five somites in females and six in males; the genital double-somite is symmetrical and is longer than wide; the caudal rami are symmetrical, with seta I well developed; the antennules of both sexes are 27-segmented and symmetrical; the antennal exopod is 7-segmented; the maxillule possesses 15 armature elements on the praecoxal arthrite and the proximal basal endite has three slender setae and one stout claw-like seta, the fifth legs are symmetrical, 4-segmented and uniramous, and the distal segment is elongate and armed with seven and six elements in males and females, respectively. Speleophriopsis mljetensis is comparated with similar species S. balearicus and S. canariensis. The new species is mainly distinguished by the armature of the genital operculum, the fifth legs of both sexes, maxilliped distal segment armature and total length of both sexes. This is the second report of a speleophriid copepod, otherwise thought to be a Tethyan relict, from an Adriatic anchialine cave. In the Bjejajka Cave, the salinity varied between 1.5 at the surface to 39 psu at the bottom, and the temperature ranged between 14.2 and 16.6 °C. It might be assumed that it colonised Bjejajka anchialine cave from its natural deep-sea habitat. However, the distributions of speleophriids in the Mediterranean are difficult to explain; therefore, this finding is of particular importance, contributing to our knowledge of the global biogeography of these Tethyan relicts.