Global diversity of tardigrades (Tardigrada) in freshwater

Tardigrada is a phylum closely allied with the arthropods. They are usually less than 0.5 mm in length, have four pairs of lobe-like legs and are either carnivorous or feed on plant material. Most of the 900+ described tardigrade species are limnoterrestrial and live in the thin film of water on the surface of moss, lichens, algae, and other plants and depend on water to remain active and complete their life cycle. In this review of 910 tardigrade species, only 62 species representing13 genera are truly aquatic and not found in limnoterrestrial habitats although many other genera contain limnoterrestrial species occasionally found in freshwater. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Strengthening Myriostoma (Geastraceae,Basidiomycota) diversity: Myriostoma australianum sp. nov

A new species in the genus Myriostoma (Geastraceae, Basidiomycota) is described from Australia. Phylogenetic analyses of the internal transcribed spacer (ITS) and large subunit (LSU) of nuclear ribosomal DNA, as well as morphological data are evidence that the new species, Myriostoma australianum, is closely related to M. capillisporum from South Africa. Additional collections under M. coliforme from Brazil and USA (New Mexico) were analyzed and confirmed as belonging to M. calongei.     

Frequent circumarctic and rare transequatorial dispersals in the lichenised agaric genus Lichenomphalia (Hygrophoraceae, Basidiomycota)

Species of the genus Lichenomphalia are mostly restricted to arctic-alpine environments with the exception of Lichenomphalia umbellifera which is also common in northern forests. Although Lichenomphalia species inhabit vast regions in several continents, no information is available on their genetic variation across geographic regions and the underlying population-phylogenetic patterns. We collected samples from arctic and subarctic regions, as well as from newly discovered subantarctic localities for the genus. Phylogenetic, nonparametric permutation methods, and coalescent analyses were used to assess phylogeny and population divergence and to estimate the extent and direction of gene flow among distinct geographic populations. All known species formed monophyletic groups, supporting their morphology-based delimitation. In addition, we found two subantarctic phylogenetic species (Lichenomphalia sp. and Lichenomphalia aff. umbellifera), of which the latter formed a well-supported sister group to L. umbellifera. We found no significant genetic differentiation among conspecific North American and Eurasian populations in Lichenomphalia. We detected high intercontinental gene flow within the northern polar region, suggesting rapid (re)colonisation of suitable habitats in response to climatic fluctuations and preventing pronounced genetic differentiation. On the other hand, our phylogenetic analyses suggest that dispersal between northern circumpolar and subantarctic areas likely happened very rarely and led to the establishment and subsequent divergence of lineages. Due to limited sampling in the Southern Hemisphere, it is currently uncertain whether the northern lineages occur in Gondwanan regions. On the other hand, our results strongly suggest that the southern lineages do not occur in the circumpolar north. Although rare transequatorial dispersal and subsequent isolation may explain the emergence of at least two subantarctic phylogenetic species lineages in Lichenomphalia, more samples from the Southern Hemisphere are needed to better understand the phylogeographic history of the genus.     

Distribution and diversity of sipunculan fauna in high Arctic fjords (west Svalbard)

Sipuncula is a relatively species poor and generally rarely investigated phylum; nonetheless, it may play a considerable role in the ecosystem. During this study sipunculan species distribution patterns in four fjords of west Spitsbergen (Kongsfjorden, Hornsund, Isfjorden and van Mijenfjorden) were examined. Material was collected during ten cruises undertaken from 1997 to 2006. A total of 381 samples were taken at 132 stations located in the four fjords and, a total number of 920 sipunculans specimens were found in 114 of those samples. The highest sipunculan species richness was observed in Hornsund (six species), followed by Kongsfjorden and Isfjorden (five species in each fjord). Sipunculan fauna in all fjords was strongly dominated by Golfingia vulgaris (80% of all sipunculan individuals in Kongsfjorden), and Golfingia margaritacea (84% in van Mijenfjorden and 40% in Hornsund) or Nephasoma diaphanes (54% in Isfjorden). Locally, sipunculans were found in high densities (max. 62 ind. 0.1 m⁻² and up to 11% of macrobenthic densities) and biomass (max. 110.87 g 0.1 m⁻² and up to 80% of total fauna biomass). At such sites, sipunculans may play an important role in bioturbation of sediments and as a food source for higher trophic levels. Sipunculans did not occur within close proximity of the glacier where they might be eliminated due to high sedimentation rate and low amounts of organic matter. Because of their importance in benthic systems, a need to include sipunculans in routine macrobenthic surveys is emphasized.     

Global diversity of springtails (Collembola; Hexapoda) in freshwater

Water-dependency appeared independently in several clades of the class Collembola, which is basically of terrestrial origin according to recent phylogenetic analyses. Though moderately diversified (less than 8,000 species), Collembola are among the most numerous terrestrial arthropods in wetland communities, with a small number of species living on the surface of water. Many species are dependent on water-saturated atmosphere of caves, and on snow or ice in high mountains. A total of 525 water-dependent species have been recognized, of which 103 are linked to free freshwaters and 109 to anchialine or marine waters. Many interstitial species are also dependent to an unknown extent on water saturation in the deep layers of the soil. The numbers provided here are underestimates, as Collembola are extremely poorly known outside the Holarctis, and the ecology of described species usually not documented. However, a general biogeographical pattern is emerging from available data. The most remarkable feature is that about 15% of the fauna is water-dependent in the holarctic region, compared to 4% in the tropics and southern hemisphere. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Global diversity of caddisflies (Trichoptera: Insecta) in freshwater

The not yet uploaded Trichoptera World Checklist (TWC) [], as at July 2006, recorded 12,627 species, 610 genera and 46 families of extant and in addition 488 species, 78 genera and 7 families of fossil Trichoptera. An analysis of the 2001 TWC list of present-day Trichoptera diversity at species, generic/subgeneric and family level along the selected Afrotropical, Neotropical, Australian, Oriental, Nearctic and Palaearctic (as a unit or assessed as Eastern and Western) regions reveals uneven distribution patterns. The Oriental and Neotropical are the two most species diverse with 47–77% of the species in widespread genera being recorded in these two regions. Five Trichoptera families comprise 55% of the world’s species and 19 families contain fewer than 30 species per family. Ten out of 620 genera contain 29% of the world’s known species. Considerable underestimates of Trichoptera diversity for certain regions are recognised. Historical processes in Trichoptera evolution dating back to the middle and late Triassic reveal that the major phylogenetic differentiation in Trichoptera had occurred during the Jurrasic and early Cretaceous. The breakup of Gondwana in the Cretaceous led to further isolation and diversification of Trichoptera. High species endemism is noted to be in tropical or mountainous regions correlated with humid or high rainfall conditions. Repetitive patterns of shared taxa between biogeographical regions suggest possible centres of origin, vicariant events or distribution routes. Related taxa associations between different regions suggest that an alternative biogeographical map reflecting Trichoptera distribution patterns different from the Wallace (The Geographical Distribution of Animals: With a Study of the Relations of Living and Extinct Faunas as Elucidating the Past Changes of the Earth’s Surface, Vol. 1, 503 pp., Vol. 2, 607 pp., Macmillan, London, 1876) proposed biogeography patterns should be considered. Anthropogenic development threatens biodiversity and the value of Trichoptera as important functional components of aquatic ecosystems, indicator species of deteriorating conditions and custodians of environmental protection are realised.     

Global diversity of cladocerans (Cladocera; Crustacea) in freshwater

Cladocera is a primarily-freshwater monophyletic group, an important component of the microcrustacean zooplankton. They inhabit most types of continental fresh and saline water habitats, occurring more abundantly in both temporary and permanent stagnant waters. Cladocera is an ancient group of Palaeozoic origin. About 620 species are currently known, but we estimate that the real number of species is 2–4 times higher. A number of currently-recognised widespread species can be expected to harbour extensive cryptic diversity. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Decomposition of mountain birch leaf litter at the forest-tundra ecotone in the Fennoscandian mountains in relation to climate and soil conditions

Litter decomposition is a key process in terrestrial ecosystems, releasing nutrients, returning CO₂ to the atmosphere, and contributing to the formation of humus. Litter decomposition is strongly controlled both by climate and by litter quality: global warming scenarios involving shifts in vegetation communities are therefore of particular interest in this context. The objective of the present study was to quantify the role of climatic environment and underlying substrate chemistry for the decomposition of standard mountain birch (Betula pubescens Ehrh. spp. czerepanovii) leaf litter at four sites, spanning the forest-tundra ecotone, in the Fennoscandian mountain range. Litter quality effects were thus held constant, but the study incorporated systematic changes in (i) latitude/altitude, (ii) `continentality', and (iii) vegetation community at each site, together with (iv) experimental manipulation of temperature using passive warming systems. The study was undertaken during a 3 year period, and forms part of a broader investigation of forest-tundra ecotone dynamics in the Fennoscandian mountains. Our results showed (1) higher decomposition rates in forest sites compared to tundra, (2) that the difference between the two vegetation communities was most pronounced at the more maritime sites, and (3) that chemistry of litter remaining after the three years experiment varied according to site and vegetation community (e.g. at the most southerly site, more lignin had decomposed at tundra communities compared with the forest). (4) Surface temperature explained 58% of the variation in mass loss at forest sites; at tundra sites, however, we hypothesise that litter moisture content was the more important factor. (5) Experimental warming lent weight to this hypothesis by reducing rates of mass loss: this reduction was likely the result of surface soil drying, an artefact of the warming treatment. We conclude that a replacement of tundra by forest would likely accelerate litter decomposition both via changes in surface and near-surface temperature and moisture regimes, although the strength of this response will vary between maritime and continental parts of the mountain range.     

Global diversity of fishlice (Crustacea: Branchiura: Argulidae) in freshwater

The Branchiura of freshwater habitats, consisting of the valid genera Argulus, Chonopeltis, Dipteropeltis, and Dolops, presently contains 113 valid species and 12 undescribed species. The entire group is composed of ectoparasitic species that usually live on fishes. The highest diversity of genera and species occurs in the Afrotropical and Neotropical regions. The diversity of the freshwater species surpasses that of species in marine and brackish waters, but this could be due to inadequate study of the fauna of the latter habitats. One species, Argulus japonicus, has been introduced from east/southeast Asia to all other continents, except Antarctica. Studies of higher level relationships place the Branchiura with either Pentastomida or Ostracoda. Hypotheses about phylogenetic relationships of either the genera or species in this group have not been proposed. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment The present paper was intended as a very brief overview of the known diversity of the Branchiura in freshwaters only, and regrettably is deficient in mention of much information and many relevant citations pertaining to the group.     

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. Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens Freshwater Animal Diversity Assessment     

Spatial scales of bacterial community diversity at cold seeps (Eastern Mediterranean Sea)

Cold seeps are highly productive, fragmented marine ecosystems that form at the seafloor around hydrocarbon emission pathways. The products of microbial utilization of methane and other hydrocarbons fuel rich chemosynthetic communities at these sites, with much higher respiration rates compared with the surrounding deep-sea floor. Yet little is known as to the richness, composition and spatial scaling of bacterial communities of cold seeps compared with non-seep communities. Here we assessed the bacterial diversity across nine different cold seeps in the Eastern Mediterranean deep-sea and surrounding seafloor areas. Community similarity analyses were carried out based on automated ribosomal intergenic spacer analysis (ARISA) fingerprinting and high-throughput 454 tag sequencing and were combined with in situ and ex situ geochemical analyses across spatial scales of a few tens of meters to hundreds of kilometers. Seep communities were dominated by Deltaproteobacteria, Epsilonproteobacteria and Gammaproteobacteria and shared, on average, 36% of bacterial types (ARISA OTUs (operational taxonomic units)) with communities from nearby non-seep deep-sea sediments. Bacterial communities of seeps were significantly different from those of non-seep sediments. Within cold seep regions on spatial scales of only tens to hundreds of meters, the bacterial communities differed considerably, sharing <50% of types at the ARISA OTU level. Their variations reflected differences in porewater sulfide concentrations from anaerobic degradation of hydrocarbons. This study shows that cold seep ecosystems contribute substantially to the microbial diversity of the deep-sea.     

Global diversity of water mites (Acari,Hydrachnidia; Arachnida) in freshwater

The Hydrachnidia (water mites) represent the most important group of the Arachnida in fresh water. Over 6,000 species have been described worldwide, representing 57 families, 81 subfamilies and more than 400 genera. The article analyzes extant water mite diversity and biogeography. Data on distribution and species richness of water mites are substantial but still far from complete. Many parts of the world are poorly investigated, Oriental and Afrotropical regions in particular. Moreover, information among different freshwater habitats is unbalanced with springs and interstitial waters disproportionately unrepresented. Therefore, more than 10,000 species could be reasonably expected to occur in inland waters worldwide. Based on available information, the Palaearctic region represents one of the better investigated areas with the highest number of species recorded (1,642 species). More than 1,000 species have been recorded in each of the Neotropical (1,305 species) and Nearctic regions (1,025 species). Known species richness is lower in Afrotropical (787 species) and Australasian (694 species) regions, and lowest in the Oriental region (554 species). The total number of genera is not correlated with species richness and is distinctly higher in the Neotropical (164 genera); genus richness is similar in the Palaearctic, Nearctic and Australasian regions (128–131 genera) and is lower in the Afrotropical and Oriental regions with 110 and 94 genera, respectively. A mean number of about three genera per family occur in the Palaeartic, Nearctic and Oriental while an average of more than four genera characterizes the families of Australasian and Afrotropical regions and more than five genera those of the Neotropical. Australasian fauna is also characterized by the highest percentage of endemic genera (62%), followed by Neotropical (50.6%) and Afrotropical (47.2%) regions. Lower values are recorded for the Palaearctic (26.9%), Oriental (24.4%) and Nearctic (21.4%). The Palaearctic and Nearctic have the highest faunistic similarity, some minor affinities are also evident for the generic diversification of Holarctic and Oriental families. The faunas of Southern Hemisphere bioregions are more distinct and characterized by the presence of ancient Gondwanan clades with a regional diversification particularly evident in the Neotropics and Australasia. This scenario of water mite diversity and distribution reflect the basic vicariance pattern, isolation, phylogenetic diversification, recent climatic vicissitudes and episodes of dispersal between adjacent land masses together with extant ecological factors can be evoked to explain distribution patterns at a global scale. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Effects of temperature elevation on a field population of Acyrthosiphon svalbardicum (Hemiptera: Aphididae) on Spitsbergen

A manipulation experiment was carried out on a field population of the aphid Acyrthosiphon svalbardicum near Ny Ålesund, on the high arctic island of Spitsbergen, using cloches to raise temperature. An average rise in temperature of 2.8 deg. C over the summer season markedly advanced the phenology of both the host plant Dryas octopetala and the aphid. Advanced aphid phenology, with concomitant increases in reproductive output and survival, and successful completion of the life-cycle led to an eleven-fold increase in the number of overwintering eggs. Thermal budget requirements in day degrees above 0°C were calculated for key life-cycle stages of the aphid. Temperature data from Ny Ålesund over the past 23 years were used to calculate thermal budgets for the field site over the same period and these were compared with the requirements of the aphid. Each estimated thermal budget was then adjusted to simulate the effect of a +2, +4, and –2deg. C change in average temperature on aphid performance. This retrospective analysis (i) confirms that the life-cycle of A. svalbardicum is well suited to exploit higher summer temperatures, (ii) indicates that the annual success of local populations are sensitive to small changes in temperature and (iii) suggests that the aphid is living at the limits of its thermal range at Ny Ålesund based on its summer thermal budget requirements.     

Anamorphs of the Bolbitiaceae (Basidiomycota, Agaricales)

We describe and illustrate thallic conidiogenesis in 14 species of the Bolbitiaceae sensu Singer studied in culture. Conidiogenesis of 12 species is shown for the first time. Bolbitius vitellinus and the investigated species of Conocybe (C. albipes, C. appendiculata, C. magnicapitata, C. semiglobata, C. subovalis, C. subpubescens, C. sulcatipes and C. teneroides) possessed a similar mode of conidiogenesis. Species of both genera formed mostly coiled conidiogenous hyphae arising sympodially from differentiated conidiophores. The anamorphs of the Agrocybe species were not uniform and predominantly differed from those of Conocybe and Bolbitius. The conidia of Agrocybe dura, A. firma and A. praecox developed by the simple fragmentation of normally branched hyphae. Sympodially proliferating conidiophores occurred in Agrocybe arvalis and A. aegerita. Secretory cells of different size and shape were found in Agrocybe and in Conocybe. Our results corroborate a close phylogenetic relationship between Bolbitius and Conocybe as well as the polyphyly of the Bolbitiaceae as currently treated, which is consistent with recent molecular phylogenetic studies. Consequently we emend the family concept based on anamorphic characters.     

Global diversity of nematodes (Nematoda) in freshwater

Despite free-living nematodes being present in all types of limnetic habitats including unfavorable conditions that exclude many other meiobenthic invertebrates, they received less attention than marine and terrestrial forms. Two-fifths of the nematode families, one-fifth of the nearly 1800 genera and only 7% of the about 27,000 nominal species are recorded from freshwater habitats. The Dorylaimia are the most successful in freshwater habitats with nearly two-thirds of all known freshwater nematodes belonging to this subclass. Members of the subclass Enoplia are principally marine though include some exclusively freshwater taxa with extreme endemism. The subclass Chromadoria includes half of the freshwater nematode families and members of the Monhysterida and Plectida are among the most widely reported freshwater nematodes. Studies on freshwater nematodes show extreme regional bias; those from the southern hemisphere are extremely underrepresented, especially compared to European freshwater bodies. The majority of records are from a single biogeographic region. Discussion on nematode endemism is largely premature since apart from Lake Baikal, the nematofauna of ancient lakes as centers of speciation is limited and recent discoveries show high nematode abundance and diversity in cryptic freshwater bodies, underground calcrete formations and stromatolite pools potentially with a high number of new taxa. Guest editors: E.V. Balian, C. Lèvêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

The distribution of ticks (Acari: Ixodidae) of domestic livestock in Portugal

This paper introduces the first countrywide faunistic study of the tick parasites on ruminants in Portugal. The aim of this study was to map accurately the distribution of the ticks Dermacentor marginatus, Rhipicephalus (Boophilus) annulatus, R. bursa, Hyalomma m. marginatum, H. lusitanicum and Ixodes ricinus in Portugal. Additional information about the abiotic preferences of these species has been obtained through the use of abiotic (temperature- and vegetation-derived) variables have been recorded from remotely sensed information at a nominal resolution of 1.1 km². A further aim was the development of predictive models of distribution using Classification and Regression Trees (CART) methodologies. Four species (R. annulatus, R. bursa, D. marginatus and H. m. marginatum) are mostly restricted to south-eastern parts of the country, under hot and dry climate conditions of Mediterranean type. H. lusitanicum has been collected almost only in the southern half of Portugal. I. ricinus has a very patchy distribution and is mainly associated with vegetation of Quercus spp., found in southern zones of the country, but it is present also in the more humid western part. A variable number of abiotic variables, mainly temperature derived, are able to describe the preferences of the tick species. It is remarkable that variables derived from maximum values of the Normalized Derived Vegetation Index (yearly or summer-derived) only apply to discriminate areas where I. ricinus has been collected. CART models are able to map the distribution of these ticks with accuracy ranging within 75.3 and 96.4% of actual positive sites.     

Global diversity of gastropods (Gastropoda; Mollusca) in freshwater

The world’s gastropod fauna from continental waters comprises ∼4,000 valid described species and a minimum of 33–38 independent lineages of Recent Neritimorpha, Caenogastropoda and Heterobranchia (including the Pulmonata). The caenogastropod component dominates in terms of species richness and diversity of morphology, physiology, life and reproductive modes and has produced several highly speciose endemic radiations. Ancient oligotrophic lakes (e.g., Baikal, Ohrid, Tanganyika) are key hotspots of gastropod diversity; also noteworthy are a number of lower river basins (e.g., Congo, Mekong, Mobile Bay). But unlike many other invertebrates, small streams, springs and groundwater systems have produced the most speciose associations of freshwater gastropods. Despite their ecological importance in many aquatic ecosystems, understanding of even their systematics is discouragingly incomplete. The world’s freshwater gastropod fauna faces unprecedented threats from habitat loss and degradation and introduced fishes and other pests. Unsustainable use of ground water, landscape modification and stock damage are destroying many streams and springs in rural/pastoral areas, and pose the most significant threats to the large diversity of narrow range endemics in springs and ground water. Despite comprising only ∼5% of the world’s gastropod fauna, freshwater gastropods account for ∼20% of recorded mollusc extinctions. However, the status of the great majority of taxa is unknown, a situation that is exacerbated by a lack of experts and critical baseline data relating to distribution, abundance, basic life history, physiology, morphology and diet. Thus, the already considerable magnitude of extinction and high levels of threat indicated by the IUCN Red List of Threatened Species is certainly a significant underestimate. Guest editors: E. V. Balian, C. Lévêque, H. Segers and K. Martens Freshwater Animal Diversity Assessment