Terrestrial crustaceans are represented by approximately 4,900 species from six main lineages. The diversity of terrestrial taxa ranges from a few genera in Cladocera and Ostracoda to about a third of the known species in Isopoda. Crustaceans are among the smallest as well as the largest terrestrial arthropods. Tiny microcrustaceans (Branchiopoda, Ostracoda, Copepoda) are always associated with water films, while adult stages of macrocrustaceans (Isopoda, Amphipoda, Decapoda) spend most of their lives in terrestrial habitats, being independent of liquid water. Various adaptations in morphology, physiology, reproduction, and behavior allow them to thrive in virtually all geographic areas, including extremely arid habitats. The most derived terrestrial crustaceans have acquired highly developed visual and olfactory systems. The density of soil copepods is sometimes comparable to that of mites and springtails, while the total biomass of decapods on tropical islands can exceed that of mammals in tropical rainforests. During migrations, land crabs create record-breaking aggregations and biomass flows for terrestrial invertebrates. The ecological role of terrestrial microcrustaceans remains poorly studied, while omnivorous macrocrustaceans are important litter transformers and soil bioturbators, occasionally occupying the position of the top predators. Notably, crustaceans are the only group among terrestrial saprotrophic animals widely used by humans as food. Despite the great diversity and ecological impact, terrestrial crustaceans, except for woodlice, are often neglected by terrestrial ecologists. This review aims to narrow this gap discussing the diversity, abundance, adaptations to terrestrial lifestyle, trophic relationships and ecological functions, as well as the main methods used for sampling terrestrial crustaceans.

The complete re-description of Caucasian local endemic stygobitic atyid shrimp Troglocaris (Xiphocaridinella) jusbaschjani Birštein, 1948 is firstly presented after its original description given by Dr. Ya. A. Birštein (1948) under the name Troglocaris schmidti jusbaschjani. The species is still known exclusively from the type locality, hydrogen sulfide bathes of the small Agura River, Sochi area, Russian Federation. Remarks on morphology, coloration of both females and males and data on ecology of Troglocaris (Xiphocaridinella) jusbaschjani Birštein, 1948 as well as remarks on morphology of relative congeneric species from Caucassus, Troglocaris (Xiphocaridinella) kutaissiana (Sadowsky, 1930) (type species of the subgenus) and Troglocaris (Xiphocaridinella) fagei Birštein, 1939, are provided. Discussion on the validity of some subgenera within the genus Troglocaris s. str. Dormitzer, 1853 are also presented.

A new species of the genus Niphargus Schiödte, 1849 (Crustacea: Amphipoda), co-occurring with water louse Asellus cf. aquaticus (Linnaeus, 1758) (Crustacea: Isopoda) in deep wells, is described from the Tarkhankut Upland, located in the northwestern part of the Crimean Peninsula. Niphargus tarkhankuticus sp. nov. corresponds to a separate phylogenetic lineage (the “tarkhankuticus” ingroup), also including several undescribed species from the coastal habitats of the Black Sea (the Crimean Peninsula, the southern Caucasus and the northern coast of Turkey), which is related to the paraphyletic European “stygius-longicaudatus” group. The divergence of the “tarkhankuticus” ingroup from the related European species probably appeared in the Late Miocene age, about 11–10 Mya, related to the separation of the Eastern Paratethys for different basins (Euxinian, Alpine and Pannopian). At the same time, the speciation within the ingroup started in Pliocene, about 5.76–3.6 Mya, and correlated with the Black Sea leveling and the drainage of coastal marine carbonate accumulations, including the Tarkhankut Upland. Intraspecific values of COI mtDNA gene markers (p-distances) for N. tarkhankuticus sp. nov. are about 2%, showing that the division into a number of isolated subpopulations, probably associated with local tectonic movements, the active formation of the river network, and further karst processes in the Tarkhankut Upland occurred during the Pleistocene (since 2.58 Mya). Analysis of stable isotopes (δ¹³C/δ¹⁵N) revealed that only discovered macrocrustaceans in the studied wells of the Tarkhankut Upland have non-overlapping trophic niches, with A. cf. aquaticus possibly feeding on algae/periphyton, while the trophic position of N. tarkhankuticus sp. nov. is close to predators.

The new pontoniine shrimp genus, Echinopericlimenes gen. nov., is suggested for four species, Periclimenes hertwigi Balss, 1913, Periclimenes dentidactylus Bruce, 1984, Periclimenes calcaratus Chace & Bruce, 1993 and Echinopericlimenes aurorae sp. nov., belonging to so-called “Periclimenes hertwigi Balss, 1913” species group sensu stricto. The new genus can be clearly separated by the unique form of hepatic tooth greatly extending beyond the pterygostomial margin of carapace, unique form of fingers of pereiopods II (chelipeds) and dactyli of ambulatory pereiopods III–V. All species referring to the new genus are similar in ecology being deep-water dwellers, usually collected deeper that 300 meters in associations with venomous sea urchins of the family Echinothuriidae (Echinodermata: Echinoidea). Remarks on ecology, description of the new species from Philippines and a key to all known species of Echinopericlimenes gen. nov. are presented.

The caridean shrimp Lysmata vittata (Stimpson, 1860) (Crustacea: Decapoda: Hippolytidae), which is found in the Pos’et Bay of the Sea of Japan is reported as new to the fauna of Russia. Sexually mature specimens of different ages were found at a depth of 2–3 m among large boulders on a sandy bottom. The presence of a stable population of L. vittata in the investigated region substantially extends the distribution area of this species in the Sea of Japan.

New genetic data on Caucasian troglobiotic shrimps collected from the territory of Russia, Abkhazia and Western Georgia are presented. Based on new genetic data on the marker region of subunit I of cytochrome oxidase of mitochondrial DNA (COXI mtDNA) of Caucasian species and other taxa of European cave shrimps (Troglocaris s.l.) from GenBank (NCBI) database, a new generic structure is presented. Based on a significant genetic divergence of COXI mtDNA subgenera of Troglocaris s.l., namely Troglocaris s.s., Xiphocaridinella and Spelaeocaris, should be considered as separate genera while Troglocaris (Troglocaridella) hercegovinensis (Babić, 1922) is suggested to be transferred within Dinaric genus Spelaeocaris as Spealeocaris hercegovinensis (Babić, 1922) comb. nov. Besides, Troglocaris bosnica shows a significant a genetic difference (at the level of the separate genus) from the remaining representatives of the genus Troglocaris s.s. Moreover, p-distances (COXI) of about 17% are supposed for generic separation within European Troglocaris-related atyid shrimps and 5% for separation of cryptic species within Caucasian Xiphocaridinella. A list of all known taxa of Troglocaris-related atyid shrimps of the European part and a discussion of the general distribution of troglocaridid atyid shrimps in the Balkans and the Caucasus are presented. A new version of divergence events between Dinaric–Caucasian Troglocaris lineages (genera) based on new genetic data is suggested.