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Xiphocaridinella shurubumu sp. n. (Crustacea, Decapoda, Atyidae), a New Stygobiotic Atyid Shrimp Species from the Shurubumu and Mukhuri Caves, Chkhorotsku, Western Georgia, Caucasus
... Maxilliped II without epipod; exopod long and slender, reaching distal segments. Maxilliped III slender, with small epipod on coxa bearing Sokolova, 2014), X. kumistavi (Marin, 2017) from the Prometheus Cave, Imereti region (see Marin, 2017) and X. motena Marin, 2019 from the Motena Cave, Samegrelo-Zemo Svaneti region (see Marin, 2018bMarin, , 2019. However, X. lechkhumensis sp.n. is unique in the "kutaissiana" group by the relatively short rostrum, not reaching the midlength of the basal segment of the antennular peduncle (see Fig. 2A, B), while other species of the group have rostrum distinctly overreaching the distal margin of the basal segment of the antennular peduncle. ...
An integrative approach resulted in a description of a new species of stygobiotic shrimps of the genus Xiphocaridinella Sadowsky, 1930 (Crustacea: Decapoda: Atyidae) from the southern part of the Racha-Lechkhumi and Kvemo Svaneti Region of the Western Georgia (SW Caucasus). The area and caves, from which this species is recorded will be flooded during the construction of the Tvishi hydroelectric power plant and it is unknown whether it will be possible to find the species again. Xiphocaridinella lechkhumensis sp.n. is easily separated from the other species of the genus both morphologically and genetically, as evidenced by barcoding segments of the mitochondrial COI gene marker (barcoding). In addition, we discovered a new population of X. kumistavi Marin, 2017 in the Satevzia Cave from Imereti Region. This population genetically diverged from the type series from the Prometheus Cave by the barcoding gap of 2.4%. The genus Xiphocaridinella in the Colchis Valley of the SW Caucasus now encompasses 15 species.
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.
Caridina ravisankarani sp. nov. is a cave-adapted species, collected during June and November 2018 and January 2019 from a limestone cave (CN2) on Interview Island, Andaman and Nicobar Islands. The shrimps were collected from a stream, sourced through the percolation of rainwater, which reduces during the post-monsoon months. The species is closely related to Caridina typus H. Milne Edwards, 1837, Caridina villadolidi Blanco, 1939 and Caridina jeani Cai, 2010. A detailed comparison of characters and a key for identification are given in the text. The present species can be diagnosed by the presence of: short rostum with edentulous upper margin and ventral margin with 2 minute teeth situated at the distal part; outer antennular flagellum with 16 segments at the basal part swollen; highly atrophied propodus and dactylus of endopod of 2 nd maxilliped; bushy long setae on fingers of 2 nd chelate legs; dactylus of 5 th pereopod with 42-43 comb-like bristles; dieresis with 18 spines; dorsal surface of telson with 4-5 pairs of spines and disto-median region doesn't end in a point, outer lateral pair of spines absent and eyes with cornea pigmentation variable, from totally absent to a small black spot. Fecundity is 1300 eggs with an average length 0.71±0.03 mm and width 0.42±0.03 mm (Mean±SD).
Based on the morpho-genetic study of stygobiotic shrimps from the genus Xiphocaridinella Sadowsky, 1930 (Crustacea: Decapoda: Atyidae), a hydrogeological connection of a number of distant caves in Central Abkhazia of the southwestern Caucasus is satisfied, which indicates the possibility of using biospeleological studies in some cases to identify karst hydrosystems together with traditional hydrogeological methods. Moreover, a new stygobiotic atyid shrimp from the genus Xiphocaridinella , X. kelasuri sp. n., is described based on morphology and analysis of mitochondrial cytochrome oxidase I DNA sequences from three distant caves. The new species is genetically divergent from relatives and phylogenetically related to Xiphocaridinella smirnovi Marin, 2020, described from the Besletka (=Tskaro) Cave. Recently, the number of described speciesof the genus Xiphocaridinella from Caucasus has increased to 13 species, while the diversity of Xiphocaridinella found in the Besletka (=Tskaro) Cave is increasing to 3 species, which is higher than in any other known cave where Troglocaris -like shrimps have been discovered.
A new stygobiotic atyid shrimp from the genus Xiphocaridinella Sadowsky, 1930 (Crustacea: Decapoda: Atyidae) is described based on morphology and DNA analysis from an underground lake inside the Motena Cave (Martvili Municipality, Samegrelo-Zemo Svaneti, Western Georgia, Caucasus). The new species is genetically well isolated from the West Georgian relatives and clearly differs from the other Caucasian congeners by specific lanceolate unarmed rostrum, turned forward, and by long fingers of pereiopod I and II in both males and females.
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