Subterranean Diversity Research Articles

A cave with remarkably high subterranean diversity in Africa and its significance for biodiversity conservation

Aziza cave, which is also known as kef Aziza or Tazouguert cave, represents an important and large karstic system that consists of more than 3.5 km of surveyed galleries, standing as the fifth most extensive cave system in Morocco and one of the ten largest in North Africa. This study unveils Aziza cave as an important spot of subterranean diversity in Africa. Here, we provide the first checklist of subterranean fauna in this cave, with 26 taxa, comprising 22 troglobiotic and 4 stygobiotic species. Of this total, eight species still require further confirmation of their status. The richest taxa include Coleoptera (5 species), Araneae (4 species), Entomobryomorpha (3 species), and Isopoda (2 species). However, it is noteworthy that only around 34.6% of the cave-restricted species found in the cave have been formally described to date. Additionally, the biodiversity of large system areas remains to be discovered as these areas need to be further explored. Furthermore, this paper highlights the broader conservation challenges faced by subterranean habitats in Morocco, particularly considering human-induced impacts on these remarkable ecosystems. We aim to draw attention to the crucial ecological role of subterranean environments and their extraordinary biological diversity. By doing so, we aim to inspire increased research and conservation initiatives, not just in this area but across Africa.

There and Back Again—The Igatu Hotspot Siliciclastic Caves: Expanding the Data for Subterranean Fauna in Brazil, Chapada Diamantina Region

The caves of Igatu, municipality of Andaraí, belonging to the region known as Chapada Diamantina represent a new hotspot of subterranean fauna. These caves are siliciclastic, which are sedimentary rocks where silica predominates, such as sandstones and (following metamorphism) quartzites, which makes them even more relevant from the point of view of subterranean diversity. For five caves, which we named Igatu Cave System (ICS), thirty-seven obligate cave species were found, of which thirty-five were troglobitic and two were stygobitic. The troglobitic taxa for ICS belong to three phyla, nine classes, 18 orders, and 32 families, representing a high phylogenetic diversity. Some taxa were, for the first time, reported as troglobitic in Brazil and even worldwide, such as Acari and scutigeromorphans (Chilopoda). We started the studies in 2009 and continue trough long-term monitoring projects. Some threats, severe in the past, such as “garimpo’’ (illegal small-scale artisanal mining) continue nowadays in an incipient way; however, the urban expansion due to the touristic appeal is also considered a threat. Our data ranked ICS as the Brazilian hotspot with the highest number of troglobitic/stygobitic species.

Subterranean Fauna of the Lukina Jama–Trojama Cave System in Croatia: The Deepest Cave in the Dinaric Karst

The Dinaric Karst is a global hotspot for subterranean diversity, with two distinct peaks of species richness in the northwest and southeast, and an area of a lower species richness in the central part. In this article, we present a species list and describe the ecological conditions of the Lukina jama–Trojama cave system, located in the central part of the Dinaric Karst. This cave system is the deepest and one of the most logistically challenging cave systems sampled so far in the Dinaric Karst. Repeated sampling resulted in a list of 45 species, including 25 troglobionts, 3 troglophiles, 16 stygobionts, and 1 stygophile. Most of the recorded species are endemic to the Velebit Mountain, while three species are endemic to the Lukina jama–Trojama cave system. Within the system, species richness peaks in the deepest third of the cave, most likely reflecting the harsh ecological conditions in the upper parts, including ice, cold winds, and occasional waterfalls. Milder and more stable deeper parts of the cave contain a rich subterranean species community, part of which is associated with two very distinct aquatic habitats, the cave hygropetric and the phreatic zone. The newly recognized hotspot of subterranean biodiversity in the central Dinaric Karst, which has emerged between the two known centers of biodiversity, further highlights the species richness in large cave systems, but also challenges the diversity patterns in the Dinaric Karst overall.

IUCN red-listing of subterranean invertebrates: problems, gaps and the future

Red-listing is a widely used approach to globally evaluate the threats that affect a species, according to a set of standardized criteria. The IUCN Red List of Threatened Species is the world's most comprehensive inventory of the global conservation status of species. It is an international reference in this field, and a powerful tool for conservation of endangered species, sites and habitats. A number of subterranean organisms of various taxonomical groups have been assessed from a few decades, and are currently being assessed, revealing serious difficulties and uncertainties linked to the special characteristics of subterranean ecosystems and species. The most critical problems, that are linked to distribution, dispersion, life cycle and sensitivity to disturbance, and some ways to overcome them, are discussed in this paper. Partly linked to this, redlisting of subterranean species has so far achieved moderate results with regard to the diversity and vulnerability of subterranean species - with the well-known exception of bats. Data drawn from IUCN online database of redlsted species reveals that subterranean invertebrates are hugely under-covered at geographical and taxonomic levels. Moreover, among red-listed species that are connected to subterranean habitats, most are stygophiles and troglophiles, i.e. not obligate cave dwellers. In contrast, very few of the species strictly linked to subterranean life (stygobionts and troglobionts) have been red-listed so far, in spite of the exceptional proneness to endemicity of subterranean invertebrate groups. On an other hand, assessments are extremely uneven across countries and across taxa. Many regions with significant cave fauna do not have any assessed subterranean species. The richest countries in subterranean diversity are not those which have the highest number of assessed species. The zoological invertebrate groups that dominate cave fauna in diversity (beetles, springtails, microcrustacea...) have contrasted proportion of redlisted species: higher for snails, very low for microcrustaceans, beetles and springtails, with rare local exceptions. Assessment difficulties underlined above, low coverage of cave fauna in available assessments, limited progress in number of red-listed species in the face of the high number of concerned species, and the limited human resources to do the job led us to favour a more pragmatic approach to subterranean invertebrates red-listing for the coming years. Really threatened subterranean species are actually not numerous, because subterranean habitats are protected from most critical disturbance that devastate so many surface habitats. The aim will be therefore to focus on the most threatened species and sites in the world, with a particular attention on mining, water pollution and large scale surface habitats destruction.

Citizen science approach reveals groundwater fauna in Switzerland and a new species of Niphargus (Amphipoda, Niphargidae)

Knowledge on the diversity and distribution of subterranean organisms is still scattered, even in faunistically relatively well-researched countries such as Switzerland. This is mostly due to the restricted access to these subterranean habitats. Better knowledge on these organisms is needed, because they contribute substantially to overall biodiversity of a region, often contain unique elements of biodiversity, and can potentially be indicative of the ecological status of subterranean ecosystems that are providing important ecosystem services such as drinking water. Past research on subterranean organisms has often used highly specialised sampling techniques and expert knowledge. Here, we show that inclusion of non-professionals can be an alternative and highly promising sampling strategy. We retrieved citizen science-based samples from municipal groundwater wells across Switzerland, mainly from the Swiss Plateau. Opportunistic samples from 313 sites revealed a previously undocumented groundwater fauna including organisms from different major invertebrate groups, with a dominance of crustaceans. Here, we studied amphipods of the genus Niphargus. Among all 363 individuals sampled, we found in total eight nominal species. Two of them, namely N. fontanus and N. kieferi, are reported for Switzerland for the first time. We also found four further phylogenetic lineages that are potentially new species to science. One of them is here formally described as Niphargus arolaensissp. nov. The description is based on molecular and morphometric data. Our study proves the suitability of citizen science to document subterranean diversity, supports groundwater conservation efforts with data, and raises awareness for the relevance and biodiversity of groundwater amphipods among stakeholders.

Ojo Guareña: A Hotspot of Subterranean Biodiversity in Spain

Ojo Guareña Natural Monument in Burgos (Spain) is an important and large karstic system. It consists of more than 110 km of surveyed galleries, and it has rich sources of organic material from the surface and permanent water circulation. It is the fourth largest cave system in the Iberian Peninsula, and one of the 10 largest in Europe. Ojo Guareña also ranks 23rd among the world’s largest caves. To date, only volcanic caves in the Canary Islands, in which between 28 and 38 subterranean species occur, are considered subterranean diversity hotspots in Spain. Here, we provide the first list of subterranean taxa present in Ojo Guareñ, which is comprised of 54 taxa that includes 46 stygobiotic and eight troglobiotic species (some still unidentified at the species level), revealing Ojo Guareña as the largest known subterranean biodiversity hotspot in Spain and Portugal. In addition, we provide a list of an additional 48 taxa, 34 stygophiles and 14 troglophiles, found in the system, whose ecological status could change with detailed biological studies, which may change the number of strictly subterranean species present in the system. Indeed, at present, these numbers are provisional as they correspond to a small part of this sizeable cave system. The biodiversity of large areas of the system remains unknown as these areas have yet to be explored from the biological point of view. In addition, a large number of samples of both terrestrial and aquatic fauna are still under study by specialists. Furthermore, evidence of cryptic species within Bathynellacea (Crustacea) indicates an underestimation of biodiversity in the karstic system. Despite these limitations, the data available reveal the typical uneven distribution of subterranean aquatic fauna, and suggest that the great heterogeneity of the microhabitats in this wide and highly connected karstic extension led to the great richness of aquatic subterranean species.

Epigean and hypogean drivers of Neotropical subterranean communities

AbstractAimIn addition to cave size and other subterranean habitat characteristics, cave entrances are important structurers of neotropical cave communities. However, little is known about the epigean ecosystems factors that might dictate the influence of entrances and the relationship among surface and cave communities, as entrance regions are ecotonal zones between the epigean and hypogean ecosystems. We aimed to assess the influence of epigean and hypogean factors as potential drivers of invertebrate species richness in Neotropical caves as well as the influence of the regional pool of invertebrate diversity on cave invertebrate diversity.LocationLimestone caves in south‐eastern Brazil.TaxonInvertebratesMethodsData were collected in 48 caves within the Cerrado biome (Brazilian Savanna). The fauna sampling was performed by a direct intuitive search (DIS). Landscape characteristics and climatic parameters were accessed using geographic information systems. The characterization of the caves occurred during each sampling event. Regional diversity was based on the Taxonomic Catalog of Brazilian Fauna. To clarify the factors that significantly influence invertebrate species richness of the caves, we used generalized linear models (GLM). The relationship between regional diversity and cave diversity was evaluated based on linear models (LM).ResultsOverall, 1,173 species were found, of which 72 were obligate subterranean dwellers. The cave total species richness was influenced by hypogean factors and epigean factors. The species richness of obligate cave dwellers was significantly explained only by cave size. The regional pool of invertebrate species influenced the levels of biodiversity in the studied caves. The taxa with troglobitic species tended to be more diverse in caves than expected.Main conclusionsIn addition to the influences of intrinsic cave variables, we highlight the importance of epigean factors on subterranean diversity in the Neotropics. The study shows the significant influence of the regional species pool on cave faunal composition. These findings reinforce the importance of considering the surrounding areas in actions regarding cave biodiversity conservation.

Niche‐based processes explaining the distributions of closely related subterranean spiders

AbstractAimTo disentangle the role of evolutionary history, competition and environmental filtering in driving the niche evolution of four closely related subterranean spiders, with the overarching goal of obtaining a mechanistic description of the factors that determine species' realized distribution in simplified ecological settings.LocationDinaric karst, Balkans, Europe.TaxonDysderidae spiders (Stalita taenaria, S. pretneri, S. hadzii and Parastalita stygia).MethodsWe resolved phylogenetic relationships among species and modelled each species' distribution using a set of climatic and habitat variables. We explored the climatic niche differentiation among species with n‐dimensional hypervolumes and shifts in their trophic niche using morphological traits related to feeding specialization.ResultsClimate was the primary abiotic factor explaining our species' distributions, while karstic and soil features were less important. Generally, there was a high niche overlap among species, reflecting their phylogenetic relatedness, but on a finer scale, niche shifts explained the realized distribution patterns. Trophic interaction was another important factor influencing species distributions – the non‐overlapping distributions of three morphologically indistinguishable Stalita species is seemingly the outcome of competitive exclusion dynamics. The distribution of the fourth species, Parastalita stygia, overlaps with that of the other species, with several instances of coexistence within caves. As inferred from the morphology of the mouthparts, the mechanism that minimizes interspecific competition is the shift in the trophic niche of P. stygia towards a more specialized diet.Main conclusionsWe showed that similarity in niches only partly correlated with the phylogenetic distance among species, and that overlaps in species distributions are possible only when a parallel shift in diet occurs. Our work emphasized how even simplified environments still maintain the potential for diversification via niche differentiation. Ultimately, we provide an ecological explanation for the diversification of life in an important hotspot of subterranean diversity.

Taxonomic Distinctness of the subterranean fauna from Peruaçu Caves National Park, state of Minas Gerais, eastern Brazil

Abstract: Limiting factors of subterranean environments, high relative air humidity and, especially, permanent darkness, represent ecological filters for organisms and biodiversity patterns of surface and subterranean communities display wide disparities. Subterranean diversity and singularity are, thus, better expressed when the common presence of rare and endemic species are considered. Our study aimed to describe the diversity of the cave fauna from 14 caves from Peruaçu Caves National Park (PCNP), eastern Brazil. We analyzed the regional diversity using the index that includes the average taxonomic distinction (TD - Δ +, AvTD). We recorded 1,674 individuals belonging to 10 Classes and 237 morphotypes, 11 troglobitic and two troglomorphic and possible troglobites. Greatest species abundance (N=330) and richness (s=76) were recorded at Lapa do Cipó cave, followed by Gruta Olhos d’Água (N=330, s=71), which shows the highest TD value (Δ + = 90.18) in relation to the others, including the richest Lapa do Cipó (Δ + = 85.24), consequence of the several taxonomic units with large number of species. The below-expected values of TD (Δ + = 87.70) may indicate anthropic impacts on these communities. Our results demonstrate that Gruta Olhos d’ Água and Lapa do Cipó caves are the most important sites for the occurrence of endemic and troglobitic species and may be part of a complex system that should be considered for a more efficient conservation planning.

Spots of high diversity of troglobites in Brazil: the challenge of measuring subterranean diversity

Subterranean ecosystems are among the most fragile and threatened worldwide. Among organisms living in the subterranean domain, source populations restricted to subterranean habitats are called troglobites, generally distinguished by sets of morphological, physiological, and ecological specializations. The singularities at both systemic (high dark and phylogenetic diversities) and species levels greatly contribute to regional and global biodiversity. However, good descriptive and interpretative knowledge about this diversity, which is important as a basis for effective conservation policies, is lacking especially for tropical areas. We describe and characterize Brazilian karst areas recognized as spots of high diversity of troglobites, highlighting particularly important cave systems. We considered not only taxonomic richness but also indicators of phylogenetic (e.g., presence of relictual taxa) and genetic diversities, the latter based on degree of specialization of individual species, i.e., accumulation of autapomorphies. For this, we used available literature and our own data, both published and unpublished. Only identifications validated by a taxonomist were considered, while all data based on parataxonomy were disregarded. We propose hypotheses based on models of origin of troglobites aiming to explain the differences between karst areas.

A new genus and species for the first recorded cave-dwelling Cavernicola (Platyhelminthes) from South America.

Species diversity of Brazilian cave fauna has been seriously underestimated. A karst area located in Felipe Guerra, northeastern Brazil, which is a hotspot of subterranean diversity in Brazil, has revealed more than 20 troglobitic species, most of them still undescribed. Based on recent samplings in this karst area, we document the occurrence of the suborder Cavernicola (Platyhelminthes) in South American hypogean environments for the first time and describe a new genus and species for this suborder. Hausera Leal-Zanchet & Souza, gen. n. has features concordant with those defined for the family Dimarcusidae. The new genus is characterized by two unique features, viz. an intestine extending dorsally to the brain and ovovitelline ducts located dorsally to the nerve cords, which is complemented by a combination of other characters. The type-specimens of Hausera hauseri Leal-Zanchet & Souza, sp. n. are typical stygobionts, unpigmented and eyeless, and they may constitute an oceanic relict as is the case of other stygobiotic invertebrates found in this karst area in northeastern Brazil.

Ancient lineage, young troglobites: recent colonization of caves by Nesticella spiders

BackgroundThe evolution and origin of cave organisms is a recurring issue in evolutionary studies, but analyses are often hindered by the inaccessibility of caves, morphological convergence, and complex colonization processes. Here we investigated the evolutionary history of Nesticella cave spiders, which are mainly distributed in the Yunnan–Guizhou Plateau, China. With comprehensive sampling and phylogenetic and coalescent-based analyses, we investigated the tempo and mode of diversification and the origins of these troglobites. We also aimed to determine which factors have influenced the diversification of this little-known group.ResultsCoalescent-based species delimitation validated the 18 species recognized by morphological inspection and also suggested the existence of cryptic lineages. Divergence time estimates suggested that Nesticella cave spiders in the Yunnan–Guizhou Plateau constituted a monophyletic troglobite clade that originated in the middle Miocene (11.1–18.6 Ma). Although the Yunnan–Guizhou Plateau clade was composed exclusively of troglobite species, suggesting an ancient common subterranean ancestor, we favor multiple, independent cave colonizations during the Pleistocene over a single ancient cave colonization event to explain the origin of these cave faunas. The diversification of plateau Nesticella has been greatly influenced by the sequential uplift of the plateau and likely reflects multiple cave colonizations over time by epigean ancestors during Pleistocene glacial advances.ConclusionsWe concluded that plateau cave Nesticella represent an ancient group of spiders, but with young troglobite lineages that invaded caves only recently. The absence of extant epigean relatives and nearly complete isolation among caves supported their relict status. Our work highlights the importance of comprehensive sampling for studies of subterranean diversity and the evolution of cave organisms. The existence of potentially cryptic species and the relict status of Nesticella highlight the need to conserve these cave spiders.

Spatial correlogram and list of Belowground genera

Broad-scale patterns of subterranean diversity are a fascinating but neglected part of biodiversity research. Carabid beetles adapted to belowground habitats form a particularly species-rich part of the subterranean fauna. We studied large-scale diversity patterns of these belowground carabids across the western Palaearctic and evaluated potential impacts of historical and contemporary environmental conditions on the distribution of these taxa, using available species richness and environmental data at country level. Regression modelling and variation partitioning showed a strong relationship between species richness and range in elevation. Potential effects of climatic variables, mainly those related to ambient energy input, were much weaker. We discuss the implications of this combination of effects, which suggests, concordant with the absence of subterranean carabids in northern and highest richness in southern Europe, a strong prevailing influence of historical processes on current richness distributions of these taxa. Previous studies did not provide clear indications for such an influence. In contrast to more mobile and widespread carabid beetles, dispersal limitation due to high adaptation of belowground carabids to subterranean habitats has probably hindered their re-colonization of former permafrost and glaciated regions. Hotspots of highest belowground diversity are located in regions with an assumed long-term stability of environmental conditions, correlating with patterns of other dispersal-limited taxa such as many endemic plants. Our study provides important new information in the discussion of potential determinants of the distinct geographic patterns of belowground diversity. Moreover, it contributes to a better understanding of range size related differences previously found in the distribution of diversity and environmental dependencies of widespread and range-restricted species within the highly diverse carabid beetles.

Belowground carabid beetle diversity in the western Palaearctic - effects of history and climate on range-restricted taxa (Coleoptera, Carabidae).

Broad-scale patterns of subterranean diversity are a fascinating but neglected part of biodiversity research. Carabid beetles adapted to belowground habitats form a particularly species-rich part of the subterranean fauna. We studied large-scale diversity patterns of these belowground carabids across the western Palaearctic and evaluated potential impacts of historical and contemporary environmental conditions on the distribution of these taxa, using available species richness and environmental data at country level. Regression modelling and variation partitioning showed a strong relationship between species richness and range in elevation. Potential effects of climatic variables, mainly those related to ambient energy input, were much weaker. We discuss the implications of this combination of effects, which suggests, concordant with the absence of subterranean carabids in northern and highest richness in southern Europe, a strong prevailing influence of historical processes on current richness distributions of these taxa. Previous studies did not provide clear indications for such an influence. In contrast to more mobile and widespread carabid beetles, dispersal limitation due to high adaptation of belowground carabids to subterranean habitats has probably hindered their re-colonization of former permafrost and glaciated regions. Hotspots of highest belowground diversity are located in regions with an assumed long-term stability of environmental conditions, correlating with patterns of other dispersal-limited taxa such as many endemic plants. Our study provides important new information in the discussion of potential determinants of the distinct geographic patterns of belowground diversity. Moreover, it contributes to a better understanding of range size related differences previously found in the distribution of diversity and environmental dependencies of widespread and range-restricted species within the highly diverse carabid beetles.

VIEWPOINT. Is the Australian subterranean fauna uniquely diverse?

Australia was historically considered a poor prospect for subterranean fauna but, in reality, the continent holds a great variety of subterranean habitats, with associated faunas, found both in karst and non-karst environments. This paper critically examines the diversity of subterranean fauna in several key regions for the mostly arid western half of Australia. We aimed to document levels of species richness for major taxon groups and examine the degree of uniqueness of the fauna. We also wanted to compare the composition of these ecosystems, and their origins, with other regions of subterranean diversity world-wide. Using information on the number of ‘described’ and ‘known’ invertebrate species (recognised based on morphological and/or molecular data), we predict that the total subterranean fauna for the western half of the continent is 4140 species, of which ~10% is described and 9% is ‘known’ but not yet described. The stygofauna, water beetles, ostracods and copepods have the largest number of described species, while arachnids dominate the described troglofauna. Conversely, copepods, water beetles and isopods are the poorest known groups with less than 20% described species, while hexapods (comprising mostly Collembola, Coleoptera, Blattodea and Hemiptera) are the least known of the troglofauna. Compared with other regions of the world, we consider the Australian subterranean fauna to be unique in its diversity compared with the northern hemisphere for three key reasons: the range and diversity of subterranean habitats is both extensive and novel; direct faunal links to ancient Pangaea and Gondwana are evident, emphasising their early biogeographic history; and Miocene aridification, rather than Pleistocene post-ice age driven diversification events (as is predicted in the northern hemisphere), are likely to have dominated Australia’s subterranean speciation explosion. Finally, we predict that the geologically younger, although more poorly studied, eastern half of the Australian continent is unlikely to be as diverse as the western half, except for stygofauna in porous media. Furthermore, based on similar geology, palaeogeography and tectonic history to that seen in the western parts of Australia, southern Africa, parts of South America and India may also yield similar subterranean biodiversity to that described here.

Assessing and conserving groundwater biodiversity: an introduction

Summary1. This paper is an introduction to and overview of a special issue on groundwater ecology with a focus on biodiversity assessment and conservation. The subterranean environment harbours unique biological communities of remarkable diversity, comprising both microorganisms and micro‐, meio‐ and macrofauna. This biodiversity of ground waters remains poorly known compared to that of freshwater surface habitats.2. The papers in this special issue summarise the outcome of a large‐scale European survey, the PASCALIS project (Protocol for theASsessment andConservation ofAquaticLifeIn theSubsurface), complemented by results from a few other comprehensive studies on groundwater diversity. The papers fall into five broad groups. The first group reviews the biology and ecology of poorly investigated but important subterranean taxa such as Bacteria and Archaea, Oligochaeta and Copepoda. Five papers deal with groundwater biodiversity patterns in the six selected PASCALIS regions. Issues addressed range from broad‐scale diversity patterns to partitioning of species richness, cryptic diversity, sampling methodology, and the use of surrogate taxonomic groups for assessing overall diversity. Four papers analyse biodiversity patterns in single European regions, the French Jura, the Walloon region of Belgium, the Lessinian Mountains of Italy and south‐western Germany. Two additional papers address the issue of site selection for the conservation and protection of groundwater species, and the fifth group of three papers expands two central PASCALIS themes – sampling adequacy and the role of dispersal. Finally, a concluding synthesis paper summarises advances in understanding groundwater biodiversity patters and conservation and points out important challenges for future research.3. Collectively, the information presented in this special issue represents the first broad‐scale examination of aquatic subterranean diversity based on a rigorously standardised sampling protocol, the first examination of stygofauna patterns in both karstic and non‐karstic aquifers, a first step toward integrating traditional and molecular taxonomic studies of groundwater biodiversity, and a start toward elaborating strategies for groundwater reserve selection.

Global diversity of amphipods (Amphipoda; Crustacea) in freshwater

Amphipods are brooding peracaridan crustaceans whose young undergo direct development, with no independent larval dispersal stage. Most species are epibenthic, benthic, or subterranean. There are some 1,870 amphipod species and subspecies recognized from fresh or inland waters worldwide at the end of 2005. This accounts for 20% of the total known amphipod diversity. The actual diversity may still be several-fold. Amphipods are most abundant in cool and temperate environments; they are particularly diversified in subterranean environments and in running waters (fragmented habitats), and in temperate ancient lakes, but are notably rare in the tropics. Of the described freshwater taxa 70% are Palearctic, 13% Nearctic, 7% Neotropical, 6% Australasian and 3% Afrotropical. Approximately 45% of the taxa are subterranean; subterranean diversity is highest in the karst landscapes of Central and Southern Europe (e.g., Niphargidae), North America (Crangonyctidae), and Australia (Paramelitidae). The majority of Palearctic epigean amphipods are in the superfamily Gammaroidea, whereas talitroid amphipods (Hyalella) account for all Neotropic and much of the Nearctic epigean fauna. Major concentrations of endemic species diversity occur in Southern Europe, Lake Baikal, the Ponto-Caspian basin, Southern Australia (including Tasmania), and the south-eastern USA. Endemic family diversity is similarly centered in the Western Palearctic and Lake Baikal. Freshwater amphipods are greatly polyphyletic, continental invasions have taken place repeatedly in different time frames and regions of the world. In the recent decades, human mediated invasions of Ponto-Caspian amphipods have had great impacts on European fluvial ecosystems.

Regional species richness in an obligate subterranean dwelling fauna – epikarst copepods

AbstractAim The diversity of the obligate cave‐dwelling fauna has proved difficult to measure because of the highly localized distributions of most species. We investigated: (1) the local and regional diversity patterns of a major component of the obligate cave‐dwelling fauna living in the epikarst zone, the karst layer closest to the surface; (2) variations in local and regional patterns of species richness; and (3) sampling sufficiency at multiple scales.Location Caves in the Dinaric Mountains of Slovenia.Methods We sampled continuously the abundance of 37 species of copepods dislodged from the epikarst from 35 ceiling drips in six caves for a period of one year. Copepods were collected in a specially designed net that allowed continuous collection.Results Based on species accumulation curves and Chao estimates of total diversity, we determined that 3–4 months of continuous sampling were sufficient to find 90% of the species in a drip, that five drips were sufficient to find 90% of the species in a cave, and that five caves were sufficient to find 90% of the species in a region.Main conclusions The epikarst copepod fauna is a significant part of the aquatic cave fauna, contributing about 20% at the regional level. Because of the scale of variation, much of which occurs within a cave, and because of the availability of continuous sampling devices, the epikarst component of subterranean diversity seems to be more thoroughly and accurately measured than do other components.

Seedling establishment, bud movement, and subterranean diversity of geophilous systems in Apiaceae

Summary Geophilous systems of plants are not only regarded as organs of underground storage. Such systems also undergo a large range of modifications in order to fulfill other ‘cryptical’ functions, e.g. positioning of innovation buds, vegetative cloning, and vegetative dispersal. Seedlings should always be the point of departure for any investigation into the structure of geophilous systems. This is because in the ability to survive of geophilous plants it is of primary importance that innovation buds can reach a safe position in the soil by the time the first period hostile to vegetation commences. Our analysis of such systems thus focused on examining the development of 34 species of the Apiaceae, beginning with their germination. Independent of life-form and life-span, all species exhibit noticeable terminal bud movement with the aid of contractile organs. Movement was found to be at least 5 mm, reaching a maximum of 45 mm. All species exhibit a noticeable contraction of the primary root. In most cases the contraction phenomenon also occurs in the hypocotyl, and some species show contraction of their lateral and / or adventitious roots. Analysis of movement shows the functional importance of pulling the innovation buds down into the soil. Furthermore, in many species it becomes obvious that, even in the first year of development, modifications of the geophilous system take place in order to fulfill other cryptical functions. Finally, our functional viewpoint highlights the redundancy of differentiating between Raunkiaer’s cryptophytes and hemicryptophytes, and proposes that plants surviving at least one unfavorable season in the soil should all be subsumed in one category, the geophilous plants.