Marin I.N.1*, Palatov D.M.1, Dbar R.S.2 2026. A new species of the genus Niphargus Schiödte, 1849 (Amphipoda: Niphargidae) from the subterranean lakes of the New Athos Cave, Abkhazia, Caucasus // Arthropoda Selecta. Vol.35. No.3: 303–317 [in English].
1 A.N. Severtsov Institute of Ecology and Evolution of RAS, Moscow 119071 Russia.
2 Institute of Ecology of the Academy of Sciences of Abkhazia, Sukhum 384900 Abkhazia.
* corresponding author
Ivan Marin: coralliodecapoda@mail.ru https://orcid.org/0000-0003-0552-8456
Dmitry Palatov: triops@yandex.ru https://orcid.org/0000-0002-8826-9316
Roman Dbar: romandbar@mail.ru https://orcid.org/0000-0003-4889-9791
doi: 10.15298/arthsel.35.3.04
ABSTRACT. A new species of the genus Niphargus Schiödte, 1849 (Amphipoda: Niphargidae), Niphargus smyri sp.n., is described based on female specimens from large subterranean lakes of New Athos Cave. Additionally, three closely related intraspecific populations (with p-distances not exceeding 5%) were recorded from nearby caves in the Gudauta–Sukhum area, including Mikhailovskaya Cave, Habyu Cave, the Bezdonnaya Yama stream (within New Athos Cave), and Duripshskaya Vodnaya Cave. Morphological characteristics of Niphargus smyri sp.n., particularly the elongation of ambulatory pereopods V–VII, probably, indicate its adaptation to permanent habitation in subterranean lakes, representing the first case of such ecological specialization (ectomorph) within the southern Caucasus region. Phylogenetic analyses demonstrate that the examined new species represent a distinct and cohesive lineage within the “aquilex–tauri” species group, being both morphologically and genetically well differentiated from all other Caucasian congeners. Niphargus smyri sp.n. can be readily distinguished from other Caucasian representatives of the genus by a combination of the following morphological features: (1) a single seta present on the dactyli of gnathopods I–II; (2) subrounded epimeral plates; (3) the presence of four long, well-developed spines on each postero-dorsolateral side of urosomite II; (4) five hooks retinacules of pleopods; and (5) elongated pereopods V–VII, representing a unique character combination within the “aquilex–tauri” species group. Morphologically, the most closely related species appears to be Niphargus fongi Fišer et Zagmajster, 2009, described from Slovenia, also sharing similar morphological features. However, molecular data for the latter species are currently unavailable in public genetic databases (e.g., GenBank (NCBI)), precluding direct phylogenetic comparison.
KEY WORDS: diversity, phylogeny, Niphargus, taxonomy, cave lakes, Caucasus.