The shrimps from the bottom: A new species of stygobiotic atyid shrimps of the genus Xiphocaridinella from the world-deepest Verevkina Cave

Abstract

A new species of the genus Xiphocaridinella Sadowsky, 1930 (Crustacea: Decapoda: Atyidae), Xiphocaridinella demidovi sp.n., and two specimens of X. dbari Marin, 2019 are described from the bottom section (-2212 m) of the world's deepest Verevkina Cave, located in the Arabika karst massif of the Gagra Ridge, southwestern Caucasus. Consequently, these species are the most deep living troglobionts/stygobionts in the world, whose taxonomic status is officially confirmed. Based on morphology and DNA analysis, both species are closely related representing sister clade separated for 6% by COI mtDNA gene marker. From the latter species and related congeners, the new species can be easily separated by a relatively long rostrum, pointed distally and reaching the distal margin of basal antennular segment, slender carpus of pereiopod II, the presence of 3 ischial spines and reduced exopods on pereiopods III-IV as well as stouter/wider telson. Due to the discovery of Xiphocaridinella demidovi sp.n., 14 species of the genus Xiphocaridinella are currently known from the Colchis Lowland of the southwestern Caucasus.