Insights on the Existence of Ancient Glacial Refugee in the Northern Black/Azov Sea Lowland, with the Description of the First Stygobiotic Microcrustacean Species of the Genus Niphargus Schiödte, 1849 from the Mouth of the Don River

Abstract

A new species of the genus Niphargus Schiödte, 1849 (Crustacea: Amphipoda: Niphargidae), co-existing with other stygobiotic amphipods, Diasynurella kiwi Marin and Palatov, 2023 and Pontonyx donensis (Martynov, 1919) (Crangonyctidae), is described from a small spring on a shore of Kiziterinka River in Rostov-on-Don City in the mouth of the Don River. Two of the three species in the studied spring, D. kiwi and the discovered Niphargus, belong to microcrustaceans not exceeding the total body size of 3 mm. The new species, Niphargus rostovi sp. nov., represents one of the smallest species within the genus and is mostly related to the Greek Niphargus karkabounasi Ntakis, Anastasiadou, Zakšek and Fišer, 2015, which is also not reaching the body size of 3 mm. One more related undescribed species is found on the Crete Island by the molecular genetic data. These species represent a separate phylogenetic lineage within the “carpathicus” species complex, which diverged from the congeners in the Late Miocene for more than 10 Mya. At the same time, the speciation within the ingroup started about 5–6 Mya, obviously correlating with the drainage of the Euxinian basin of the Eastern Paratethys, connecting the lower Don and southern Greece areas. Niphargus potamophilus Birštein, 1954 is also first recorded from the mouth of the Belbek River in the Crimean Peninsula, closing the known area from the Kuban River delta to Rostov-on-Don area and further along the western coast of the Black Sea to Bulgaria. Analysis of the recent records of long-time lineages of endemic/subterranean/stygobiotic animals unable to disperse for long distances assumed that glacial refugium existed at the mouth of the Don River, along with the South Caucasus (Colchis) and the southern Caspian (Hyrcania), where many species have survived several periods of glaciation since the late Miocene.

A new semi-terrestrial Cryptorchestia Lowry et Fanini, 2013 (Amphipoda: Talitridae) from the southwestern Caucasus and the Ciscaucasian Plain

“…Currently, the southern glacial refugia in the Western Palearctic, such as the Iberian, Italian and Balkan peninsulas, Anatolia, the southern Caucasian Kolkhida coastal lowland (Colchis) and the southern coastal valley of the Caspian Sea (Hyrcania), are well recognized [Taberlet et al, 1988;Schmitt, 2007;Keppel et al, 2012]. Also recently, a glacial refugia have been found on the northern slope of the Greater Caucasus Ridge Palatov, Sokolova, 2021;Anistratenko et al, 2022] and the Northern Black/ Azov Sea coastal plain [Marin, Palatov, 2023]. They were localities of conservation and subsequent settlement of species, and contributed to the speciation of divided populations in the Pleistocene [Marin, 2020;.…”

“…In the case of Cryptorchestia ciscaucasica sp.n., the genetic divergence is somewhat lower (2.5%) than the generally accepted values about (3.75-4%), however, the presence of well-marked morphological differences and geographic isolation with strict geographical distribution (local endemism) of both species suggests allopatric speciation since the middle of the Pleistocene (Qua-ternary period), during the last 1.8-1.0 Mya [Knowlton, Weight, 1998;Schubart et al, 1998] or 0.5 Mya [Loeza-Quintana et al, 2019]. It is very likely that these species were separated by episodes of cooling/ glaciation since 1.65 Mya, the most powerful of which occurred during the Cromerian Stage in the Middle Pleistocene, about 0.8-0.5 Mya [Turner, 1996;Marin, Palatov, 2023].…”

The Diversity of Freshwater Stygobiotic Crustaceans in the Republic of North Ossetia–Alania Provides New Evidence for the Existence of an Ancient Glacial Refugium in the North Caucasus Region

“…However, this is true for the southern slope of the Greater Caucasian Ridge, whereas the current knowledge of stygobiotic fauna is relatively poor on the northern slope, probably due to the lack of studies to date [19,20]. Nevertheless, there are exceptions, for example, the recently discovered ancient glacial refugium in the northern Black/Azov Sea Lowland near the mouth of the Don River [21].…”

A new species of the genus Proasellus (Crustacea: Isopoda: Asellidae) from the Abin River basin, with the preliminary data on the diversity of the genus in the southwestern foothills of the Russian Caucasus

“…Groundwater ecosystems are among the most understudied habitats of our planet (Saccò et al, 2023). Current knowledge on the diversity of subterranean and hyporheic crustaceans of the Caucasus is still fragmentary, despite the fact that quite a lot of publications with a description of stygobiotic diversity have appeared recently (Marin, 2017(Marin, , 2019(Marin, , 2020Marin, Palatov, 2019a, 2023aGrego et al, 2020;Palatov, Sokolova, 2021;Marin et al, , 2023Rendoša et al, 2021;Anistratenko et al, 2022;. Most likely the reason is that Caucasus is the second region of the Western Palearctic (after the Balkan Peninsula) in terms of the size of karst area, the variety of landscapes and climatic conditions (Myers et al, 2000;Krever et al, 2001), as well as groundwateradapted biodiversity is mainly composed of short-range species with restricted distributions (Trontelj et al, 2009;Eme et al, 2018).…”