The remarkable Ponto-Caspian amphipod diversity of the lower Durso River (SW Caucasus) with the description of Litorogammarus dursi gen. et sp. nov. Author Marin, Ivan 0000-0003-0552-8456 A. N. Severtsov Institute of Ecology and Evolution of RAS, 119071, Moscow, Russia & coralliodecapoda @ mail. ru; vanomarin @ yahoo. com; https: // orcid. org / 0000 - 0003 - 0552 - 8456 coralliodecapoda@mail.ru Author Palatov, Dmitry 0000-0002-8826-9316 A. N. Severtsov Institute of Ecology and Evolution of RAS, 119071, Moscow, Russia & triops @ yandex. ru; https: // orcid. org / 0000 - 0002 - 8826 - 9316 triops@yandex.ru Author Copilaș-Ciocianu, Denis 0000-0002-6374-2365 Laboratory of Evolutionary Ecology of Hydrobionts, Nature Research Centre, Vilnius, Lithuania & denis. copilas-ciocianu @ gamtc. lt; https: // orcid. org / 0000 - 0002 - 6374 - 2365 denis.copilas-ciocianu@gamtc.lt text Zootaxa 2023 2023-06-06 5297 4 483 517 http://dx.doi.org/10.11646/zootaxa.5297.4.2 journal article 10.11646/zootaxa.5297.4.2 1175-5326 8009123 6E7C1770-D107-4FF7-A2DC-F2A693E581F1 Litorogammarus mazestiensis ( Marin & Palatov, 2021 ) comb. nov. Fig. 18 a, b Echinogammarus mazestiensis Marin & Palatov, 2021: 3 , figs 1–3 [ type locality—Mazesta, Sochi]. Material examined. 5 ÔÔ , 5♀♀ , LEMMI — Northeastern Black Sea , Russian Federation , Krasnodar region , Sochi area , estuary of the Mazesta River , 43°32’35.3”N , 39°47’28.5”E , under stones and among river pebbles, hand net sampling, Marin I.N. & Palatov D.M. leg., 16.05.2019 . Diagnosis. Head with oblique anteroventral lobe (see Marin & Palatov, 2021 : Supplementary Figure S5 b ). Pleon with urosomite I bearing a pair of long median setae; urosomite II with 1 marginal long spine on each side and a pair of median short spines; urosomite III with 1 long marginal spine of each side (see Marin & Palatov, 2021 : Figure 3 g ). Antenna I smooth, non-setose, with 6-segmented accessory flagellum (see Marin & Palatov, 2021 : Figure 2 b ). Antenna II slightly shorter that AI, with long ventral setae, without calceoli both in males and females. Pereopods V–VII : basis (article 2) with straight dorsal margin and feebly marked ventral lobes (see Marin & Palatov, 2021 : Supplementary Figure S3 ). Epimeral plates with sharp and produced posteroventral angles. GenBank accession number. OP466441, OP466428 (this study). Habitats and distribution. The species is presently known only from its type locality, the mouth (estuary) of the Mazesta River , Sochi area , SW Caucasus , Russia (see Marin & Palatov, 2021 ), living under pebble and stones, where it forms significant aggregations .