Search Results (53)

China’s southwestern karst landscapes support remarkable cavefish diversity, especially within Sinocyclocheilus, the world’s largest cavefish genus. Using integrative taxonomic methods, we describe Sinocyclocheilus wanlanensis sp. nov., found in a subterranean river in Guizhou Province. This species lacks horn-like cranial structures; its eyes are either reduced to a dark spot or absent. It possesses a pronounced nuchal hump and a forward-protruding, duckbill-shaped head. Morphometric analysis of 28 individuals from six species shows clear separation from related taxa. Nano-CT imaging reveals distinct vertebral and cranial features. Phylogenetic analyses of mitochondrial cytb and ND4 genes place S. wanlanensis within S. angularis group as sister to S. bicornutus, with p-distances of 1.7% (cytb) and 0.7% (ND4), consistent with sister-species patterns within the genus. Sinocyclocheilus wanlanensis is differentiated from S. bicornutus by its eyeless or degenerate-eye condition and lack of bifurcated horns. It differs from S. zhenfengensis, its morphologically closest species, in having degenerate or absent eyes, shorter maxillary barbels, and pelvic fins that reach the anus. The combination of morphological and molecular evidence supports its recognition as a distinct species. Accurate documentation of such endemic and narrowly distributed taxa is important for conservation and for understanding speciation in cave habitats. Full article

Two new subterranean species of the genus Spelaeogammarus da Silva Brum, 1975 in Serra do Ramalho municipality, Bahia state, and Montes Claros municipality, Minas Gerais state, both in Brazil, are described herein. With these additions, the genus now comprises ten known species. This study includes a comparative table detailing the diagnostic characteristics of all Spelaeogammarus species and an updated genus diagnosis. Additionally, it provides insights into the species’ habitats and the threats they face. Some of the type localities mentioned in this study are not within protected areas, making these species particularly vulnerable to environmental risks. Threats primarily arise from surrounding land use, which can impact the water table and disrupt food resource availability. The discovery of these new troglobitic species underscores the urgent need for their inclusion in future threatened species assessments and highlights the importance of conservation measures to protect both the species and their cave habitats, along with the surrounding landscape. Finally, the discovery of these new species highlights the remarkable diversity of Spelaeogammarus in subterranean environments, emphasizing the need for further research and conservation efforts. Full article

Caves and subterranean habitats in general support a unique set of organisms that are adapted to the dark and nutrient-limited environment. The high selection pressure and limited gene flow between semi-isolated caves have generally resulted in a high level of endemicity among the depauperate cave fauna. The cave fauna is vulnerable to a range of anthropogenic factors, including mining and excessive usage as show caves. The awareness of the need for conservation of these unique habitats has been growing in recent years, but not uniformly. In this paper, we use Web of Science to look at how the subterranean research output in the ecology and conservation area in southern Africa compares to the rest of the world. We find that while Africa as a whole has a disproportionately low publication rate, southern Africa is relatively well represented, though driven exclusively by South Africa. However, unlike the development in the rest of the world, the number of publications has not risen much in recent years and is mainly focused on vertebrates. In this paper, we discuss the reasons for this discrepancy and use well-known show caves in the region as case studies to identify research priorities and promote more awareness of the conservation needs of caves in southern Africa. Full article

Zokor is a group of subterranean rodents that are adapted to underground life and feed on plant roots. Here, we investigated the intestinal microbes of five zokor species (Eospalax cansus, Eospalax rothschildi, Eospalax smithi, Myospalax aspalax, and Myospalax psilurus) using 16S amplicon technology combined with bioinformatics. Microbial composition analysis showed similar intestinal microbes but different proportions among five zokor species, and their dominant bacteria corresponded to those of herbivores. To visualize the relationships among samples, PCoA and PERMANOVA tests showed that the intestinal microbes of zokors are largely clustered by host species, but less so by genetics and geographical location. To find microbes that differ among species, LefSe analysis identified Lactobacillus, Muribaculaceae, Lachnospiraceae_NK4A136_group, unclassified_f_Christensenellaceae, and Desulfovibrio as biomarkers for E. cansus, E. rothschildi, E. smithi, M. aspalax, and M. psilurus, respectively. PICRUSt metagenome predictions revealed enriched microbial genes for carbohydrate and amino acid metabolism in E. cansus and E. smithi, and for cofactor and vitamin metabolism as well as glycan biosynthesis and metabolism in E. rothschildi, M. aspalax, and M. psilurus. Our results demonstrated differences in the microbial composition and functions among five zokor species, potentially related to host genetics, and host ecology including dietary habits and habitat environment. These works would provide new insight into understanding how subterranean zokors adapt to their habitats by regulating intestinal microbes. Full article

The black olm (Proteus anguinus parkelj Sket & Arntzen) is an endemic species found exclusively in the Dobličica River subterranean water systems of the Dinaric karst in southern Slovenia. These unique habitats are vulnerable to contamination due to rapid water flow, primarily from nitrates from agricultural fertilisers and untreated urban wastewater. The safe limit of nitrate concentration for olms is 9.2 mg NO₃⁻/L, yet measurements in karst springs have shown levels ranging from 3 mg to over 20 mg NO₃⁻/L. The SWAT modelling tool assessed agri-environmental and land use scenarios for their impact on nitrate leaching. Using the model, we identified hotspots with high nitrogen leaching potential that require immediate attention and implementation of better agricultural practices for fertiliser use. For these hotspots, the most effective approach combines scenarios of cover crops (R2), reduced fertilisation (R3), crop rotation (R4), and conversion of cropland to grassland (E2, E4, E5), potentially decreasing nitrate leaching by up to 60%. Implementing the best scenarios is expected to reduce nitrogen levels below the limit value of 9.2 mg NO₃⁻/L, essential for maintaining the black olm habitat. Full article

Cavernicolous scorpions are difficult to collect and study due to their often inaccessible habitats. Some have evolved unique morphological adaptations, known as troglomorphies, including reduced sclerotization and pigmentation, reduction and/or loss of eyes, attenuation and elongation of the appendages, which assist them to thrive in dark, humid and low-energy input environments. Cavernicolous scorpions are classified into accidentals, trogloxenes, troglophiles, and troglobites. The Balkans, and particularly the Dinaric Karst region, host a diverse cave-adapted fauna, including scorpions. Despite an 1895 report of a blind scorpion from Bosnia and Herzegovina, the first truly troglobitic European scorpion, Euscorpius studentium Karaman, 2020, was only described a few years ago, based on two immature specimens. In the present contribution, this unique species is redescribed based on the first adult specimens; the ecological classification of all currently known cavernicolous Euscorpiidae Laurie, 1896, is updated; a key to the identification of cavernicolous scorpions occurring in the Dinaric Karst is provided; and the historical and geographical factors affecting the distribution and conservation of cavernicolous scorpions in the Balkans is reviewed. Full article

Numerous and diverse groundwater habitats suitable for sustaining aquatic invertebrate communities exist across Australia. These habitats include enclosed subterranean aquifer systems, fractured rock, alluvial aquifers, perched aquifers, artesian springs, and spring-fed seeps and marshes. Crustaceans are a dominant member of these groundwater-associated invertebrate communities, and amphipods, both stygobiont and associated epigean species, are particularly diverse yet are still relatively poorly known. We review both the diversity and distributions of Australian amphipods associated with groundwater habitats, describing hotspots of diversity, providing notes on the unique Australian habitats, and examining the extraordinary species diversity and endemism of the Australian species. Our review highlights the significance of Australian groundwater ecosystems, their associated biodiversity, and the importance in considering these ecosystems in groundwater conservation management plans. Full article

The subterranean blind mole rat, Spalax, has evolved significantly over 47 million years to thrive in its underground habitat. A key enzyme in this adaptation is heparanase, which degrades heparan sulfate (HS) in the extracellular matrix (ECM), facilitating angiogenesis and releasing growth factors for endothelial cells. Spalax heparanase has various splice variants influencing tumor growth and metastasis differently. We report a novel splice variant from a hypoxia-exposed kidney sample resulting from exon 12 skipping. This variant maintains the translation frame but lacks enzymatic activity, offering insights into Spalax’s unique adaptations. Full article

Fishes in marine caves have attracted limited attention by the scientific community in comparison to subterranean fishes which have lost eyes and pigmentation. They constitute a largely unexplored component of marine fish diversity, except for the relatively well-studied marine caves of the Mediterranean Sea. These habitats are characterized by steep environmental gradients of decreasing light and decreasing water exchange. The fishes recorded so far in marine caves are not exclusive residents of this habitat and they are also present at least in the other mesolithial habitats. In the Mediterranean marine caves, 132 fishes have been recorded to date, representing about 17% of the total Mediterranean fish species richness. Most of these species are reported from the anterior cave zones where some light still exists, while a smaller number of species are known from the totally dark zones. Among them, 27.3% are accidental visitors, 53.8% are the regular mesolithial visitors and switchers between mesolithion and open water, 5.3% are permanent residents of the mesolithion, but also occur in other habitats, and 13.6% are exclusive permanent residents of mesolithion. Some mesolithial exclusive permanent residents recorded in marine caves share similar morphology, probably as adaptations to these habitats. Full article

A review and partial revision of the diversity of freshwater stygobiotic crustaceans in the territory of the Republic of North Ossetia–Alania, in the North Caucasus, is presented here. Previously, two species of the genus Proasellus Dudich, 1925 (Isopoda, Asellidae), P. uallagirus Palatov & Sokolova, 2020 and P. irystonicus Palatov & Sokolova, 2020, and one species of the genus Niphargus Schiödte, 1849 (Amphipoda, Niphargidae), N. alanicus Marin & Palatov, 2021, were described from the hyporhean/underground habitats (hyporhea) in the area. However, further research using an integrative approach has revealed that only a single species of the genus Proasellus (P. uallagirus) is actually widely distributed in the hyporhean riverbed habitats in the area, while the diversity of the genus Niphargus is higher than previously known. Six more new Niphargus species— namely, N. ardonicus sp. nov., N. sadonicus sp. nov., N. fiagdonicus sp. nov., N. tschertschesovae sp. nov., N. osseticus sp. nov. and N. zeyensis sp. nov., were discovered from the various hypogean underground water sources (i.e., springs and seeps) and are described in this article. Their phylogenetic relationships with their congeners, as well as their ecology and known distribution, are discussed. Furthermore, molecular genetic analysis, with an interpretation of the estimated divergence time, suggests that the studied hyporheic/stygobiotic crustaceans started to diverge from related European and Balkan sister species during the Late Miocene, approximately 8–5.8 Mya, with the reduction in the Paratethys and the uplifting of the Caucasus Mountains. Local speciation was led by local geological processes and karst fragmentation during the Late Pliocene and Early Pleistocene periods, starting around 5.3 Mya. The obtained data suggest that the mountainous area of the North Ossetia–Alania could be considered as a post-Pliocene glacial refugium for subterranean and stygobiotic fauna—the first known for the North Caucasus region. Full article

Subterranean environments are often characterized by a natural gradient of microclimatic conditions and trophic resources, showing a higher trophic availability and a lower microclimatic stability in the shallowest area (close to the cave entrance), while the opposite occurs in the deepest sections. The shallowest areas of subterranean environments (e.g., the entrance and twilight zone, Mesovoid Shallow Substratum) act as ecotones between the surface habitats and the deep areas, creating a particular habitat which can be exploited by numerous species with different degrees of adaptation to subterranean environments. Species living in these ecotones may hold a key role in sustaining the entire ecosystem, as they are likely one of the major drivers of allochthonous organic matter. Indeed, these species are usually facultative cave-dwellers, meaning that they are able to exit and forage on the surface. Once these species are back inside the cave, they provide the local community with different typologies of organic matter (e.g., feces, eggs), which represent one of the most important sources of organic carbon. Therefore, studying which ecological features may exert significant effects on the abundance of these species may be of great help in understanding the ecosystem dynamics and the functional role of each species. In this study we analyzed the data collected through a year-round monitoring program, aiming to assess the potential effects that both abiotic and biotic features may have on the abundance of three facultative cave species. We focused on seven caves located in Monte Albo (Sardinia, Italy). The cave environments were divided into 3-meter sectors, and within each cave sector, microclimatic and biological data were seasonally recorded. We focused on the following facultative cave species: the spiders Metellina merianae and Tegenaria sp. and the snail Oxychilus oppressus. Different relationships were observed between the ecological features and the abundance of the three species. The two spiders were more abundant in warmer cave sectors closer to the cave entrance, especially the M. merianae. On the other hand, the snail tended to be more abundant farther from the cave entrance and in more illuminated cave sectors, probably because sunlight promotes the abundance of some of its trophic resources (e.g., lichens, vegetation). Furthermore, O. oppressus was the only species whose abundance and cave distribution was significantly affected by seasonality. This study provides useful and novel information to understand the population dynamics of facultative cave species and their role in subterranean ecosystems. Full article

The genus Trogolaphysa comprises 81 described species distributed across the Neotropical and Afrotropical regions. In the Americas, just over half of the species found in subterranean habitats have a reduced eye number (0–5 eyes). Subterranean species are of interest as models to study the evolution of morphological adaptations. Many subterranean species of Trogolaphysa were described before the introduction of chaetotaxy as a diagnostic tool and thus remain incompletely described and diagnosed. To identify gaps in descriptions and facilitate the identification of newly collected forms, we provide standardized summary descriptions, species diagnoses, diagnostic tables, and a dichotomous key to the 33 Neotropical species of Trogolaphysa with reduced eye number. As a result of this synthesis, we describe two new troglobiontic species, Trogolaphysa reneaui n. sp. and Trogolaphysa welchi n. sp. from Belizean caves. Full article

Located in Lestelas-Balaguères massif, central northern Pyrenees, France, the Baget catchment covers 13.25 km² and is highly karstified: so far, more than 80 caves have been recorded. The main outlet of the system, the exsurgence de Las Hountas, has an average flow of 550 L/s. Downstream, it is connected with the hyporheic of the Lachein stream. The Baget system, formed by both the karstic system and the hyporheic, has been intensively investigated by cave biologists and is known to be a hotspot for subterranean biodiversity. The synthesis provided here lists no less than 17 troglobionts and 40 stygobionts, with 3 single site endemics, making the Baget system the richest subterranean hotspot in the Pyrenees. This is notably due to the diversity of subterranean habitats and to the comprehensive knowledge of the stygofauna, likely unmatched at the European scale. Considering the significant speleological findings of the last 15 years that have not been yet biologically investigated, we can expect new discoveries, especially for the troglofauna. Full article

The conquest of land by arthropods is commonly believed to be a surface phenomenon associated with the arrival of photosynthetic plants, atmospheric oxygenation, and an ozone shield in the mid-Paleozoic Era. However, recent molecular and fossil evidence suggests terrestrial fauna may have first appeared in the Cambrian, before the proliferation of plants and ozone, which are thought to be essential for survival. This raises the question—how could arthropods survive on land without established plants and an ozone shield? We propose a hypothesis that chemolithoautotrophic cave ecosystems, independent of photosynthesis, may have served as a subsurface stepping stone, providing a possible explanation for the land invasion enigma. Chemolithoautrophic caves have offered abundant food and radiation protection, enabling ancient arthropods to evolve strategies to adapt to new frontiers through gradual dispersion from the sea to shielded cave waters, then to cave hygropetric margins of cave waters, and, finally, to the surface. Full article