Search

This is the first published report of tardigrades in Newfoundland and Labrador. Twenty-six species have been identified so far, including four new records for Canada and one new record for North America. Although there is some overlap of species with those found in earlier Canadian studies, there are some interesting discrepancies. The rare occurrence and restricted distribution of the very few heterotardigrades (three species and 30 specimens) found so far in Newfoundland is noteworthy, as is the occurrence of several tardigrade species whose former records have been mainly for Greenland. It appears the environmental conditions in Newfoundland can support a number of species that would normally be restricted to a more northerly distribution. A comparison of the species found in Newfoundland with those of a number of other northern countries suggests that the Newfoundland species are most similar to those found in Greenland and mainland Canada.

The buccopharyngeal apparatus of several species of tardigrades, including both heterotardigrades and eutardigrades, has been prepared for scanning electron microscopy (SEM) by using a new method developed and refined for this purpose. The buccalpharyngeal apparatus from three well-known species are described in detail and preliminary attempts to interpret the function of some of the structures are presented. The chosen species are used as examples and the new findings are compared to studies from the literature. The species used are: Echiniscoides sigismundi , Halobiotus crispae and Milnesium tardigradum . A redescription of the buccopharyngeal apparatus, in particular the stylets, the stylet supports, the stylet sheaths and their interrelationships, is presented for each species. For H. crispae the cuticular elements of the pharynx are also redescribed from this material. The potential for new information available with this method is discussed, together with the possible artifacts and difficulties the method may cause.

Micro-distribution of soil inhabiting tardigrades was studied in a sub-alpine coniferous forest (alt. 1,840 m a. s. l.) on the eastern slope of Mt. Yatsugatake, Central Japan. Eight cylindrical soil samples were taken from the forest floor. Each sample was divided into 10 slice samples of 1 cm thick. Tardigrades were extracted from samples by Baermann funnels, identified to specific level and counted. The average number of tardigrades in the study site is 74,058/m 2 . High densities sometimes occurred at depths greater than 5 cm. Consequently for investigating tardigrade populations, 5cm depth core sampling is insufficient in this type of habitat. Composition of the main groups of species reveals that shallow layers (1, 2 or 3 cm depth) are frequently dominated by the Diphascon -group. Macrobiotus -group species generally occurred in higher abundance in the deeper layers. It is very interesting that there are some different patterns of soil micro-distribution in tardigrade species.

The distribution of tardigrades in the states of the southern United States is poorly known. There are no published records from the state of Louisiana, while in Arkansas only one species has been reported. Samples of mosses and lichens from trees and rocks were collected from three sites in central and southern Louisiana and six sites in western Arkansas. Leaf litter samples were collected from one site in Louisiana. Nine species of tardigrade were found in Louisiana and 22 in Arkansas. The number of species per sample ranged from one to six.

Available information about Mediterranean tardigrades regards mainly the insular and peninsular Italian coasts, but also Malta, the Alboran Sea, Spain, France, Albania, Morocco, Algeria, Tunisia, Cyprus, and Lebanon. The Mediterranean Tardigrades, more than 70 species, are Heterotardigrada, mainly the order Arthrotardigrada with several families, and the order Echiniscoidea with only the family Echiniscoididae. Coralligenous detritus seems to be the most favourable kind of sediment in which the highest values of biodiversity are reached. Halechiniscidae is the most important family in the subtidal zone, whereas Batillipedidae are more frequent in the intertidal zone. A study of 4 submarine cave populations has been carried out. Neoarctidae and Neostygarctidae, considered as the most ancient families, have only been found in the Mediterranean Sea to date. This could mean that Arthrotardigrada originated in the old Thetys Sea from which the basin of the Mediterranean Sea was formed.

Significant differences occurred in the density of tardigrades, rotifers, and nematodes and the diversity of tardigrades between collecting sites located upwind and downwind from a coal-burning power plant in Missouri. The oak tree species and lichen genera also varied in the two areas. Tardigrade and rotifer densities were greater in upwind sites, whereas nematode density was higher in downwind samples. One tardigrade species (Ramazzottius sp.) was found only at the upwind sites, and one species (Echiniscus sp.) was only in the downwind samples. In contrast, three species (Macrobiotus sp., Minibiotus sp., and Milnesium tardigradum) were found both upwind and downwind but in different densities in the two areas. The study presents baseline data for long-term monitoring of the effects of environmental factors on nematode and rotifer densities as well as tardigrade density and diversity.

The tardigrade fauna of the African continent is reviewed and presented graphically using Worldmap, a Geographical Information System (GIS) developed for exploring geographical diversity patterns in large biological datasets. References to the African tardigrade fauna have been gathered from published literature and supplemented with unpublished species information from the collection of Prof. Reinhardt M. Kristensen (RMK), Zoological Museum, University of Copenhagen. 156 species belonging to 36 genera of tardigrades are present. They consist of 105 eutardigrade species and 51 heterotardigrade species, of which 42 species are semiterrestrial and 9 species are marine. The presence of tardigrades are reported from 20 countries, but of these 9 are represented by a single reference. Marine tardigrades in particular have been neglected, with only a single report from the shores of the African continent. Data from the RMK collection of samples from Egypt is included in the analysis. The scattered and sparse knowledge of the African tardigrade distribution makes general conclusions difficult, but emphasises the large regions which require further investigation. The current distribution patterns corresponds with easy accessible or ‘tourist’ locations. Regions where GIS could be used to illustrate ecological preferences are also pointed out by the analysis. Isohypsibius malawiensis sp. n. is described from Lake Malawi. It has a smooth body surface and lacks eyes. The heteronych claws are without lunulae, but below the claws a double arched cuticular bar is present. The dorsal and ventral apophyses of the buccal tube have a large drop-shaped swelling. The first macroplacoid is the largest followed by the second, which is only slightly larger than the third; microplacoid is absent. Males are smaller than females. Females lay only one to two very large eggs in the exuvium. The Malpighian tubules are clover-shaped. The new species is interstitial in coarse sediment and no other tardigrade species were present.

A seasonal survey of tardigrade populations in the riparian zone of the Choccolocco Creek, Alabama, was undertaken from August 1994 through December 1995. Six sites within the riparian zone were sampled in different portions of the creek. At each site, 3 trees with cryptogams were sampled six times during survey period. From a total of 108 samples, 1,588 tardigrades were extracted and individually mounted on slides in Hoyer's medium. The community was dominated (86%) by specimens in the genus Macrobiotus . One species of Echiniscus was new to science and will be described in a separate paper. No significant difference was found between tardigrade occurrence (total number of individuals) and season, moss genera, or tree species. However, there was a significant relationship between the number of tardigrades and site, indicating the need for additional replicate samples. Simpson's and Shannon-Wiener's species diversity indices indicated that species richness and evenness were low. Jaccard's and Standard's community similarity indices suggested that the communities within the riparian zone were dissimilar along Choccolocco Creek.

We report a study on anhydrobiotic survival in the eutardigrades Richtersius coronifer and Ramazzottius oberhaeuseri. In each of these species, we investigated the anhydrobiotic survival of two populations, one from Sweden and one from Italy. We found that anhydrobiotic survival was similar in the Swedish and the Italian populations in both species, indicating no divergence with respect to anhydrobiotic capacity. Body size had a strong effect on the probability to recover from anhydrobiosis, but the effect was in opposite direction in the two tardigrade species. Ramazzottius oberhaeuseri had a considerable higher overall survival (66%) than R. coronifer (40%). This result is in line with earlier studies that found R. oberhaeuseri to have a very high water-retentive capacity.

The distribution of tardigrades within the layers of the cushion moss Grimmia alpicola Hedwig, 1801 was investigated. The aim of this study was to determine the tardigrade species present within the moss layers during both wet and dry periods and to determine if migration occurred in response to changing moisture conditions. Samples of the moss were removed from concrete caps on brick fence posts before and after rainfall and separated into two sections (top and bottom). The tardigrades from each layer and moisture condition were identified to species. Data for each species were statistically analyzed with a two-way analysis of variance (ANOVA) to compare the numbers of individuals present in the top and bottom layers of the moss under both wet and dry conditions. Five tardigrade species were identified, including two species new to science: Macrobiotus sp. n.; Milnesium tardigradum Doyere, 1840; Echiniscus viridissimus Peterfi, 1956; Echiniscus perviridis Ramazzotti, 1959; and Echiniscus sp. n. The new species will be described in a forthcoming paper. No significant differences were found in the numbers of individuals of four of the five species in each layer within the moss or for each moisture condition. Only one species, E. viridissimus , was significantly more frequent in the top layer of the moss, regardless of moisture condition. Migration within the moss cushion was not detected in any of these five species as a result of changes in moisture conditions. In xeric moss species, it may not be beneficial for tardigrades to migrate to avoid desiccation. Instead, they apparently undergo anhydrobiosis in both the top and bottom layers of the moss cushion.

Several marine caves in Australia have been investigated for meiofauna using a freshwater technique to shock large sediment samples. Several species of nematodes, gastrotrichs, crustaceans, polychaetes and aplacophorans were found, and one new species of kinorhynch has been described. In addition, two new species of loriciferans from marine caves in New South Wales, Australia, are under description. This paper is the second in a series describing the unique meiofauna in submarine caves and inland anchialine caves of Australia. The paper deals with the tardigrade fauna of two caves, Jim's Cave and Fish Rock Cave, both located off the coast of New South Wales. The sediment consists of carbonate sediments (shell-hash to shell-gravel) mixed with organic detritus. The abundance of tardigrades is very low in the two caves, but the species diversity is very high. The following arthrotardigrade genera have already been found: Actinarctus, Batillipes, Dipodarctus, Halechiniscus, Raiarctus, Styraconyx, Tanarctus, Tholoarctus, and Wingstrandarctus. The cave fauna of tardigrades seems not to be related to the well-investigated high energy beach fauna of tardigrades along the East Coast of Australia. Most surprising is the discovery of the species Actinarctus neretinus known from the Italian cave, Grotta Cattedrale, supporting the theory that marine caves serve as refuges for an old Tethyan fauna.

Summary 1Tardigrades comprise a micrometazoan phylum that is a sister group of the arthropods. 2They are components of the meiobenthos in lotic habitats, and ≈ 50–70 species have been reported in such habitats world-wide. Approximately 800 species have been identified from all marine, freshwater, and terrestrial habitats. 3Taxonomy is based primarily on the morphology of the claws, buccal-pharyngeal apparatus, cuticle and eggs. 4Reproductive modes include sexual reproduction (amphimixis) and parthenogenesis. The sexual condition of individuals may be either gonochorism, unisexuality, or hermaphroditism. Moulting occurs throughout the life of the tardigrade. 5Latent states (cryptobiosis, including encystment, anoxybiosis, cryobiosis, osmobiosis and anhydrobiosis) enable tardigrades to withstand unfavourable environmental conditions. 6Population densities, life histories, dissemination and biogeography of freshwater species are poorly known.

A new semiterrestrial tardigrade species of the genus Calcarobiotus is described from the Imperial Palace of Japan as the third species of the genus which has been previously known only from South Africa. The new species, Calcarobiotus imperialis, is closely related to C. occultus Dastych, but can be distinguished from the latter mainly by the absence of a spine on the tip of each egg process, and by having larger pores on egg surface, a narrower buccal tube, and larger claws.

We report preliminary data of analysis genomic DNA stability and gene expression both in active and dormant stages of number of invertebrates and a plant exposed to real space flight environment onboard ISS (International Space Station) during 2005/2006. Perspectives of DNA studies using latent stages of living organisms exposed to outer space in the forthcoming space programs are discussed., 資料番号: AA0063349098

A new species of marine tardigrade is described coming from the muddy sediment of the Antarctic deep sea. Angursa antarctica sp. nov. is characterized by the presence of balloon-shaped primary clavae, long lateral cirri, long cephalic cirri, spines on legs I, hemispherical capsule-shaped papillae on legs IV, and short external peduncles. Geographical distribution of the genus Angursa extends to Antarctic waters, suggesting a cosmopolitan distribution for this bathyal and abyssal genus. A table comparing the main differentiating characteristics of the species of Angursa is presented.

The tardigrade faunas of six Arctic sites (Canadian Axel Heiberg I., east and west coasts of Greenland, Iceland, Svalbard, Novaya Zemlya and the Russian Taimyr Peninsula) form, with those of northern North America, a coherent “Nearctic-Arctic” biogeographic cluster. This cluster is distinct from that of “Northern and Alpine Europe”. Few, if any, Arctic tardigrades survived Pleistocene glaciation in situ amongst ice-free refugia. Similarly, few/none moved south ahead of the advancing ice-cap into the deglaciated Palaearctic and Nearctic and subsequently returned north during the Holocene deglaciation. It is more probable that most Arctic tardigrades are derived from wind-blown Nearctic propagules that colonized the region during the Holocene.

Three new marine heterotardigrades, Archechiniscus symbalanus, and Styraconyx craticuliformis of the family Halechiniscidae and Echiniscoides andamanensis of the family Echiniscoididae, are reported on the basis of the specimens sieved from intertidal barnacles in the Thai coast of the Andaman Sea. Archechinisos symbalanus n. sp. is related to Archehiniscus minutus Grimaldi De Zio and D'Addabbo Gallo, but discernible from it by possessing median cirrus, stylet sheath, sensory spine of leg I, prominent basal processes on all leg pairs, and S‐shaped seminal receptacles. Styraconyx craticuliformis n. sp. is similar to S. craticulus (Pollock) in bearing the grid‐like dorsal cuticle, but distinguished from it by the shape of claws and cirrophore of primary clava. Ediniscoides andamanensis n. sp. is related to Echiniscoides pollocki Hallas and Kristensen and E. sigismundi sigismundi (M. Schultze) in sharing the same patterns of sensory leg appendages and the claw configuration of 8–8–8–7, but characterized by t...

The Tardigrada is a cosmopolitan phylum of pre-Pangaean origin, yet tardigrade families and genera show distinct biogeographic components isolated by two major geological events. Separate Laurasian and Gondwanan familial clusters correlate with the Triassic disintegration of Pangaea, while discrete Antarctic, Australian and New Zealand familial/generic clusters relate to the subsequent Jurassic/Cretaceous disintegration of Gondwana

The ultrastructure of the adult pharynx of the eutardigrade Halobiotus crispaeis described for the active, sexually mature summer form as well as for the winter form known as pseudosimplex 1. The total number of cells is 54: 27 muscle cells, 12 apical cells, nine nerve cells and six buccal tube cells. The development of the pharynx is described on the basis of five ontogenetic stages. Three of them are reconstructed three-dimensionally with the help of computer techniques. The number of cells composing the pharynx remains constant from an early embryological stage and each cell can be traced and recognized in the adult pharynx. The findings regarding the ultrastructure of the pharynx are compared to previous descriptions. A hypothesis regarding the coordinated function of the organ and a preliminary attempt to define the plesiomorphic condition of the tardigrade pharynx are presented. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.

Dung of the early-evolved Amami rabbit of Japan was surveyed for the presence of fungi which attack microscopic organisms. Several species of predacious nematophagous fungi and species endoparasitic in nematodes and rotifers were found. In addition, zygomycetous species attacking amoebae and tardigrades, and one flagellate zoosporic species holocarpic in various host organisms, were found.

The Author first recalls the past of eutardigrade taxonomy and indicates the main factors that for a long time restrained its progress. One consequence of a superficial analysis is that very wide individual variability has been erroneously attributed to many species, and this has become the main problem for tardigrade taxonomists. The situation began to change after 1969 because of the first attempts to eliminate the above mentioned problems. Novelties gave impetus to the revision of tardigrade taxonomy, and genuine systematics, finally based on phylogenetics, became popular. Today the morphological characters are considered more in depth and studies utilising DNA sequences are more in fashion; they are surely useful and allow the distinction of morphologically very similar species. However, in the author’s opinion, this progress will be possible only if the molecular studies are always associated with careful morphological studies, which, in the meantime, will be more and more detailed also thanks to the use of the Scanning Electron Microscopy (SEM).

The Faroe islands (62°N, 7°W) are an archipelago of 18 small islands situated in the northeast Atlantic ocean between Iceland and the Shetland islands. A zoogeographic investigation (2001-2004) of the limnoterrestrial tardigrade fauna of these islands revealed 48 limnoterrestrial species and subspecies and one marine species, of which 29 were new records for the Faroe islands. Among the findings were three species in the recently described genus belonging to the family Eohypsibiidae. A faunistic comparison was also done with Iceland, Svalbard islands, Disko island (Greenland), Greenland (West and East), Scotland, England and with Newfoundland. On the basis of presence/absence data of the tardigrade species from the different countries a cluster analysis was computed, based on Bray-Curtis similarities, and a dendrogram was constructed. The interesting results show that the Faroese tardigrade fauna is mostly similar with Iceland, which could be expected, but more surprising it is also very similar to the tardigrade fauna on Disko island (West Greenland). Several of the reported species exhibit a boreo-alpine disjunction (i.e. species only found in northern latitudes and in high altitudes farther south). These facts could indicate that the tardigrade fauna on the islands is very ancient and could have survived glaciation periods in refuges such as nunataks which occurred on the Faroes during glaciation periods. This study also includes a closer inspection of the altitudinal distribution of the tardigrade species found compared with similar data from Poland.

DNA barcoding is a technique proposed by Hebert and co-workers in 2003 for discriminating species through analysis of a single gene barcode locus. It aims to obtain a better taxonomic resolution than that achieved through morphological studies, and to avoid the decline in taxonomic knowledge. Today DNA barcoding is a global enterprise, and the implementation of the idea has seen a rapid rise (more than 1900 papers published to date on different organisms). Nonetheless, controversy still arises regarding barcoding and taxonomy. It is important to note that DNA barcoding does not focus on building a tree-of-life or on doing DNA taxonomy, even though sometimes it has been used for these purposes. DNA barcoding rather focuses on producing a universal molecular identification key based on strong taxonomic knowledge that should be included in the barcode reference library. In the phylum Tardigrada, DNA barcoding represents a recent approach to species identification and to help in solving taxonomic problems, especially considering the diminutive size of these animals and the paucity of morphological characters useful for taxonomy. In the framework of the MoDNA Project (Morphology and DNA), carried out by our research group in collaboration with several colleagues, we are combining the study of a fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) with morphological data, in a wide sense (cuticular structures, chromosomes, data on sex ratio and reproduction), to form an integrative taxonomy approach for tardigrade species identification. We believe that without verified reference sequences from voucher specimens that have been authenticated by qualified taxonomists, there is no reliable library for newly generated sequences with which to be compared. Methods and protocols for standardized results are focused on obtaining tight correspondence between tardigrade morphology (and egg shell morphology, when useful), possibly both light and scanning electron microscopy images, and molecular sequence. This approach is particularly useful in describing new species, and important when applied on material collected in species type localities. Results using this approach are presented, primarily focusing on a number of species from the so-called Macrobiotus hufelandi group.

In this paper we present the Tardigrada Register (www.tardigrada.net/register) : a free, comprehensive, and standardised online data repository for tardigrade taxonomy. We outline key problems of the modern tardigrade systematics and we propose the Register as a potential solution to some of them. We then describe the idea, structure and works of the service and discuss challenges it may face. However, most importantly, we hope to convince fellow Tardigradologists that sharing their data via the Register will benefit the entire community of the contemporary and future tardigrade researchers.

Worldwide knowledge of tardigrade fauna is still limited, and many areas such as South America are not well studied. The collection of new substrates in Argentinean urban areas provided an opportunity to describe the new tardigrade species Macrobiotus kristenseni sp. nov. This species has been studied with an integrative taxonomic approach, analysing its morphology by light and scanning electron microscopy, and considering two genes (cox1 and 18S rRNA) for DNA barcoding and phylogenetic purposes. The species belongs to the Macrobiotus hufelandi group of species, and it is characterized by egg processes in the shape of elongated cones with truncated and enlarged apexes, and by a high genetic distance with respect to closely related species (cox1: 18.2–33.4%). Morphological and molecular data show that the Macrobiotus hufelandi group of species has to be considered a true biological entity; one of the more widespread tardigrade lineages in continental environments. http://www.zoobank.org/urn:lsid:zoobank.or...

A new species of the previously monospecific marine tardigrade family Neostygarctidae is described. Neostygarctus lovedeluxe n. sp. was found from a submarine cave in Miyako Islands, Japan. This is the first record of Neostygarctidae from the Pacific. The new species is easily distinguished from the previously known N. acanthophorus by its number of dorsal spines, as N. lovedeluxe has two spines each on the three dorsal body plates in contrast to one in N. acanthophorus. Furthermore the morphology of the two clawed juvenile is reported for the first time in Neostygarctidae, providing new insights into the common sequence in some ontogenic traits.

Currently, loss of habitat is the greatest threat to biodiversity, yet little is known about its effect on microscopic animal taxa, such as Tardigrada. One of the causes of habitat destruction is forest fire, both natural and anthropogenic. The latter is commonly used in agriculture to kill insect pests, as a soil preparation, or conservation to create habitat mosaics. In Portugal, 42% of fire frequency is anthropogenic. There is no consensus on the impact of fires on biodiversity, with studies pointing towards different conclusions. Different methods and target taxonomic study groups may partly explain this paradigm. This study is the first into possible effects of habitat destruction on tardigrade populations, in which we analysed the taxonomic and genetic variations of tardigrades from a fire affected location in a Portuguese natural park. Sampling was performed over a 10-year period, from 2000 to 2010. The location was affected by a small fire in 1998 and a big fire in 2003. A total of 11 species from nine separate genera was recorded, from which 19 cox1 haplotypes were identified. Our data suggest a negative effect of a forest fire on tardigrade populations. Taxonomic and genetic richness, as well as abundance show lower levels in the years after a fire, compared with the preceding years. Additionally, the population recovered visibly faster after the small fire than after the bigger one. This is consistent with larger fires destroying larger forest areas, leaving fewer animals at a farther distance available for re-colonisation. Most species found before the main fire are also found after it, indicating these tardigrades have a high recolonisation capability. However, only three of all recorded haplotypes were found both pre and post the main fire, which indicates genetic diversity loss as a direct consequence of fire. Therefore, we conclude that habitat destruction by means of forest fire has a detrimental effect on tardigrade biodiversity, and may have similar effects on other small animals.

Humans have had such a profound effect on global ecosystems, including biodiversity, that Anthropocene is being increasingly used as a chronological term to mark the period of greatest human impact. No areas show the effect of human impact on the environment more than cities, which often have novel combinations of species in unique communities. Tardigrades (Phylum Tardigrada) have often been collected in cities, but studies dedicated to urban tardigrade biodiversity are few, and those comparing urban diversity with nearby rural or natural sites even fewer. In this paper we compare the diversity and abundance of tardigrade species in Lake Charles with a nearby forested nonurban site, Sam Houston Jones State Park (SHJSP). Although tardigrade density did not differ significantly between Lake Charles and SHJSP, species richness and diversity were greater in SHJSP (17 species, H1=3.01) than in Lake Charles (8 species, H1=1.30). All but one species found in Lake Charles also occurred in SHJSP. The number of species found in Lake Charles lies within the range (5-10) found in previous urban surveys. All tardigrade studies comparing urban with nearby nonurban habitats have found lower species richness in cities.

In studies developed in the mid- and infralittoral of Cupe Beach (Pernambuco), in the shallow infralittoral of Saint Peter and Saint Paul Archipelago, and in the continental shelf of northeastern Brazil, we recorded for the first time in Brazilian waters specimens of Archechiniscus marci, Batillipes lesteri, Florarctus hulingsi, Halechiniscus tuleari, Angursa lingua, Raiarctus aureolatus, Actinarctus doryphorus doryphorus, Tanarctus dendriticus, Tanarctus velatus, Neoarctus sp. and Neostygarctus sp., as well as six other species that had been previously recorded in the region. Hence, the number of marine tardigrade taxa recorded in Brazil was increased to twenty-seven.

We isolated a species of tardigrade from moss samples collected from Langhovde and Skarvsnes, near Syowa station, East Antarctic, from which we cultured a parthenogenetic strain in Petri dishes with co-occurring cyanobacteria or green algae. This culture was maintained at both 4 and 10ºC, though the latter proved more suitable for growth. Eggs were laid free, rather than in exuviae. We isolated the 18S rRNA sequences from this tardigrade, identical to that of Acutuncus antarcticus from King George island, South Shetland islands. Morphological analyses via both light and scanning electron microscopy also show general agreement with characteristics of A. antarcticus: dorsal and ventral apophyses for the insertion of stylet muscles and dorsal longitudinal thickening on the anterior part of buccal tube; presence of pharyngeal apophyses, two macroplacoids and absence of a microplacoid; the surface structure of egg; and claw shape. Peribuccal lamellae were absent, but six oval swellings surrounded the mouth opening. An additional study of moss pillars from lake Hotoke-ike, Skarvsnes, proved the existence of the same tardigrade taxon living at the bottom of the lake.

Tardigrades are known as one of the most radiation tolerant animals on Earth, and several studies on tolerance in adult tardigrades have been published. In contrast, very few studies on radiation tolerance of embryonic stages have been reported. Here we report a study on tolerance to gamma irradiation in eggs of the eutardigrade Richtersius coronifer. Irradiation of eggs collected directly from a natural substrate (moss) showed a clear dose-response, with a steep decline in hatchability at doses up to 0.4 kGy followed by a relatively constant hatchability around 25% up to 2 kGy, and a decline to ca. 5% at 4 kGy above which no eggs hatched. Analysis of the time required for eggs to hatch after irradiation (residual development time) showed that hatching of eggs after exposure to high doses of gamma radiation was associated with short residual development time. Since short residual development time means that the egg was irradiated at a late developmental stage, this suggests that eggs were more tolerant to radiation late in development. This was also confirmed in another experiment in which stage of development at irradiation was controlled. No eggs irradiated at the early developmental stage hatched, and only one egg at middle stage hatched, while eggs irradiated in the late stage hatched at a rate indistinguishable from controls. This suggests that the eggs are more sensitive to radiation in the early stages of development, or that tolerance to radiation is acquired only late in development, shortly before the eggs hatch, hypotheses that are not mutually exclusive. Our study emphasizes the importance of considering specific cell cycle phases and developmental stages in studies of tolerance to radiation in tardigrades, and the potential importance of embryonic studies in revealing the mechanisms behind the radiation tolerance of tardigrades and other cryptobiotic animals.

Little is known about the genetic structure of microscopic animals from mosses and lichens. A few studies have investigated the geographic variation in tardigrades from mosses, but so far no study has investigated the intra-population or local clonal lineage variation. Echiniscus testudo (Echiniscoidea: Echiniscidae) belongs to a large cosmopolitan genus of terrestrial tardigrades comprising more than 150 species. It is a common tardigrade in mosses in the temperate part of the Northern hemisphere, and is highly tolerant of desiccation and freezing. In a previous study, we reported a maximum of 1.28% sequence variation (uncorrected p-distance) in cytochrome c oxidase subunit I (COI) haplotypes between clonal lineages covering a large geographical area. However, in this previous study we used pooled specimens to constitute a sample, and the genetic diversity from single specimens within a locality therefore remains unknown. Accordingly, the present study investigates the COI sequence variation and haplotype diversity between single specimens of E. testudo collected at three Danish localities, separated by 80 m and 186 km. A total of 10 COI haplotypes were found in the present study (Et2, Et3, Et9, Et12-Et18); only three of these were previously reported (Et2, Et3 and Et9). The uncorrected COI sequence diversity ranged between 0-2.07%, with haplotype Et18 having the highest genetic difference. The second most variable haplotypes (Et14, Et15, and Et17) all showed a maximum diversity of 1.19% compared to the other haplotypes. No general pattern of haplotype distribution was evident. Our data suggest that E. testudo has dispersed across the Baltic sea as haplotypes Et3, Et13 and Et14 are present at all three localities. The most likely dispersal mode is passive wind dispersal in the cryptobiotic tun stage. The current study emphasises that numerous sequences from single specimens are needed to describe the genetic diversity within single moss cushions.

Semi-terrestrial tardigrades are well-known for their tolerance to a variety of environmental extremes, including desiccation, freezing and radiation. Despite several attempts to reveal the genetic and molecular mechanisms behind the resilience of tardigrades, it is still unknown how these animals are able to maintain the integrity of their cellular components under severe stress. Quantitative or qualitative changes in molecular compounds (e.g., carbohydrates, proteins) are expected, and have been the main line of research towards understanding the tolerance of tardigrades. In radiation tolerant bacteria, a tolerance mechanism based on manganese has been proposed. We evaluate this hypothesis in tardigrades and provide the first data on element composition in desiccated and non-desiccated specimens of two eutardigrade species, Richtersius coronifer and Milnesium cf. asiaticum. A focused 2 MeV proton microbeam was utilised to determine the elemental content, distributions and concentrations, using the ion beam analytical technique particle induced X-ray emission (PIXE). The presence of six elements – phosphorus, sulphur, chlorine, potassium, calcium and iron – were confirmed in all tardigrade specimens, at levels up to a few mg g–1. However, manganese was found in less than 10% of the analysed specimens, and in low amounts, thus our study provides no evidence for the manganese hypothesis. We also show that the distributions and/or concentrations of some elements differ between the two species as well as between the dehydrated and hydrated state. In particular, very low levels of iron were found in dehydrated M. cf. asiaticum. Our analysis shows that the PIXE technique is a useful tool for investigating questions on the distribution of elements both in dehydrated and hydrated tardigrades.

In a previous paper the occurrence of nematodes, rotifers and tardigrades in 29 samples from nunataks in Dronning Maud Land, East Antarctica taken 1991/1992 was recorded. In this study, a more thorough description of animal distribution is possible by adding 64 new samples (1993/1994), thus increasing the total number from these studies to 93 soil samples from 11 nunataks. The number of species recorded from the area has now increased from 27 to 34. The populations were patchily distributed and the species composition differed between nunatak areas in Vestfjella and Heimefrontfjella. In most samples only one or a few species of nematodes or tardigrades were found. The number of rotifer species in a particular sample varied from nought to seven. Rotifers occurred in most of the samples (76%) with a maximum density of 750 specimens/gram dry weight. The nematode distribution was more restricted. Nematodes were found in high abundance on only four of the nunataks and occurred in 35% of the samples with a maximum density of 210 specimens/gram dry weight. Tardigrades were found in 39% of the samples with a maximum density of 580 specimens/gram dry weight. Some of the tardigrade species were widely distributed, whereas others were found only on specific nunataks. The distribution pattern of the fauna on two of the nunataks, Basen and Fossilryggen, was studied in greater detail and the results showed little difference in peak abundance and species composition between samplings carried out during two southern summer seasons.

The brain of Echiniscus viridissimus , Peterfi, 1956 is composed of a series of orthogonally arranged neuropils. The most anterior neuropils are circumbuccal, positioned dorso- and ventrolateral to the buccal tube and are associated with ganglia for sensory receptors of the mouth cone. Posterior to these are neuropils and ganglia for the (1) internal cirri and (2) cephalic papillae, external cirri, cirri A and clavae. They are joined by two pairs of vertical tracts to neuropils lateral to the buccal tube. A model based on the postcephalic organization of the tardigrade nervous system is used to propose a transformation of segmental ganglia that gives an arrangement congruent with the pattern of neuropils in the brain. The analysis suggests that the brain is derived from nervous elements of four segments with the fourth segment having contributed paired dorsal ganglia and their connecting vertical tracts to the first trunk ganglia of the ventral chain. The organization of the head of tardigrades is compared with that of other lobopods and arthropods and several possible key evolutionary innovations are offered. In addition homologous characters for the heads of tardigrades and other lobopods and arthropods are proposed and the nomenclature for the tardigrade cephalic nervous system is discussed.

Findings are reported from samples collected in tundra in Greenland, Iceland and the Svalbard Islands. In total 58, tardigrade species are reported, only 12 of which are common to all three areas. Forty-three species are reported from Greenland (11 new to the country and two new to science); 33 species are reported from Iceland (14 new to the country); 21 species are reported from the Svalbard Islands (4 new to the archipelago). A description ofHypsibius pachyunguissp. novandFujiscon triodonsp. nov. (Eutardigrada, Hypsibiidae) is given.

Effects of fungivorous and predatory soil arthropods on free-living nematodes and tardigrades were studied in a factorial microcosm experiment. A stepwise increase in faunal complexity was obtained by adding soil arthropods to defaunated humus samples from an irrigated+fertilized and an untreated stand of Scots pine. The effects were assessed after 103 and 201 days at 15°C and a soil moisture content of 50% water-holding capacity. The study showed that a diverse community of “fungivorous” arthropods (collembola and oribatid mites), present in numbers similar to those in the field, reduced the abundance of nematodes. A complete community of fungivorous and predatory arthropods (e.g., gamasides, spiders, and cantharid larvae) further strengthened this repressive effect. Certain nematode genera were more affected than others. Tardigrades seemed to be efficient predators on nematodes, but their numbers were, in turn, strongly reduced by predatory arthropods. Because predatory arthropods fed on both nematodes and their tardigrade predators, the impact of arthropod predators on nematode regulation was greater than it appeared to be on the basis of nematode numbers. Humus type also interacted with the other factors. Nematode numbers were initially higher in the untreated humus than in the irrigated+fertilized humus. However, because tardigrade populations increased only in the untreated humus, nematode numbers decreased more in this humus than in the irrigated+fertilized humus. The study demonstrates that nematode abundance can be regulated by a number of types of interacting predators.

The ecological distributions of tardigrade species from six sites on Roan Mountain, Tennessee-North Carolina, were determined in a study begun by D.R. Nelson in 1971. Three new species of eutardigrades were discovered in Nelson's study, but remained undescribed. A follow-up to that study was initiated by K.L. McGlothlin in 1988 to determine the long-term stability of tardigrade populations at two of Nelson's original collection sites. Two of Nelson's three new eutardigrade species were rediscovered by McGlothlin, and one newPseudechiniscusspecies was found. The description of one of the eutardigrades,Hypsibius roanensis, was published previously. The remaining eutardigrade found during both studies, a new species ofCalohypsibius, is described here:Calohypsibius schusterisp. nov.

The limnoterrestrial tardigrade fauna of the Philippines is completely unknown. In this paper, we describe the first ever limnoterrestrial water bear species from this southeast Asian country, Mesobiotus philippinicus sp. nov., found in a moss sample collected in Quezon City. Apart from morphometrics and imaging in light microscopy, we also analysed the new species under scanning electron microscope and sequenced four DNA markers differing in mutation rates, three nuclear (18S rRNA, 28S rRNA, and ITS-2) and one mitochondrial (COI). This allowed not only a detailed description but also provided barcodes to aid future species identification. The new species belongs to the harmsworthi group and is most similar to M. diffusus (Binda & Pilato, 1987), M. pseudocoronatus (Pilato et al., 2006), M. montanus (Murray, 1910) and M. mottai (Binda & Pilato, 1994), but differs from these species by whorled egg processes and dimensions of some morphometric traits. The 28S rRNA, ITS-2 and COI sequences presented in this paper are the first published DNA sequences for the genus Mesobiotus.

The Western Hemisphere or the New World, also known as the Americas (North, Central and South America, associated islands and included seas) have historically been divided into two Realms, the Nearctic and Neotropical based on terrestrial biogeography. The coasts of these two terrestrial realms are bordered by six marine realms, 14 marine provinces and 67 marine ecoregions. From current literature, a comprehensive list of the marine tardigrade fauna from the Americas is presented. Data on marine tardigrades were obtained from 385 published Records of the Occurrence (RoO) of a species, their location, tidal zone, and the substrates from which they were reported. Authors’ identifications were accepted at face value unless subsequently amended. Thirty genera and 82 species or subspecies are reported from the Americas; 49 species are documented from margins of the terrestrial Nearctic realm (North America) and 48 from terrestrial Neotropical realm (South America) with only 17 species occurring in both. We define cosmopolitan distribution for marine tardigrades as occurring in or on the margins of five of the seven oceans, only two species of marine tardigrade meets this standard. From the Americas 39 species have been described as new to science, 32 species appear restricted to the hemisphere. Taxa were assigned to marine ecoregions based on adjacent geopolitical units (country, states, provinces, etc.) described in published records. Although tardigrades have been reported from all six marine realms, they are only known from 21 of the 67 ecoregions. Most marine tardigrade sampling in the Americas has focused on near shore substrate (sand, mud, barnacles); for some species no substrates have been reported. The west coasts of both continents have little or no data about tardigrade presence.

Antarctica is an ice-dominated continent and all its terrestrial and freshwater habitats are fragmented, which leads to genetic divergence and, eventually, speciation. Acutuncus antarcticus is the most common Antarctic tardigrade and its cryptobiotic capabilities, small size and parthenogenetic reproduction present a high potential for dispersal and colonisation. Morphological (light and electron microscopy, karyology) and molecular (18S rRNA and cytochrome c oxidase subunit I (COI) genes) analyses on seven populations of A. antarcticus elucidated the genetic diversity and distribution of this species. All analysed populations were morphologically indistinguishable and made up of diploid females. All specimens presented the same 18S rRNA sequence. In contrast, COI analysis showed higher variability, with most Victoria Land populations presenting up to five different haplotypes. Genetic distances between Victoria Land specimens and those found elsewhere in Antarctica were low, while distances between Dronning Maud Land and specimens from elsewhere were high. Our analyses show that A. antarcticus can still be considered a pan-Antarctic species, although the moderately high genetic diversity within Victoria Land indicates the potential for speciation events. Regions of Victoria Land are considered to have been possible refugia during the last glacial maximum and a current biodiversity hotspot, which the populations of A. antarcticus mirror with a higher diversity than in other regions of Antarctica.

Tardigrades are able to tolerate almost complete dehydration by reversibly switching to an ametabolic state. This ability is called anhydrobiosis. In the anhydrobiotic state, tardigrades can withstand various extreme environments including space, but their molecular basis remains largely unknown. Late embryogenesis abundant (LEA) proteins are heat-soluble proteins and can prevent protein-aggregation in dehydrated conditions in other anhydrobiotic organisms, but their relevance to tardigrade anhydrobiosis is not clarified. In this study, we focused on the heat-soluble property characteristic of LEA proteins and conducted heat-soluble proteomics using an anhydrobiotic tardigrade. Our heat-soluble proteomics identified five abundant heat-soluble proteins. All of them showed no sequence similarity with LEA proteins and formed two novel protein families with distinct subcellular localizations. We named them Cytoplasmic Abundant Heat Soluble (CAHS) and Secretory Abundant Heat Soluble (SAHS) protein families, according to their localization. Both protein families were conserved among tardigrades, but not found in other phyla. Although CAHS protein was intrinsically unstructured and SAHS protein was rich in β-structure in the hydrated condition, proteins in both families changed their conformation to an α-helical structure in water-deficient conditions as LEA proteins do. Two conserved repeats of 19-mer motifs in CAHS proteins were capable to form amphiphilic stripes in α-helices, suggesting their roles as molecular shield in water-deficient condition, though charge distribution pattern in α-helices were different between CAHS and LEA proteins. Tardigrades might have evolved novel protein families with a heat-soluble property and this study revealed a novel repertoire of major heat-soluble proteins in these anhydrobiotic animals.

Tardigrades are microscopic aquatic animals with remarkable abilities to withstand harsh physical conditions such as dehydration or exposure to harmful highly energetic radiation. The mechanisms responsible for such robustness are presently little known, but protection against oxidative stresses is thought to play a role. Despite the fact that many tardigrade species are variously pigmented, scarce information is available about this characteristic. By applying Raman micro-spectroscopy on living specimens, pigments in the tardigrade Echiniscus blumi are identified as carotenoids, and their distribution within the animal body is visualized. The dietary origin of these pigments is demonstrated, as well as their presence in the eggs and in eye-spots of these animals, together with their absence in the outer layer of the animal (i.e., cuticle and epidermis). Using in-vivo semi-quantitative Raman micro-spectroscopy, a decrease in carotenoid content is detected after inducing oxidative stress, demonstrating that this approach can be used for studying the role of carotenoids in oxidative stress-related processes in tardigrades. This approach could be thus used in further investigations to test several hypotheses concerning the function of these carotenoids in tardigrades as photo-protective pigments against ionizing radiations or as antioxidants defending these organisms against the oxidative stress occurring during desiccation processes.

Tardigrade feeding apparatus is a complex structure with considerable taxonomic significance that can be schematically divided into four parts: buccal ring, buccal tube, stylet system, and pharynx. We analyzed the fine morphology and the tridimensional organization of the tardigrade buccal–pharyngeal apparatus in order to clarify the relationships between form and function and to identify new characters for systematic and phylogenetic studies. We conducted a comparative analysis of the cuticular structures of the buccal–pharyngeal apparatuses of twelve eutardigrade species, integrating data obtained by SEM and LM observations. Morphological diversity was observed and new cuticular structures such as the stylet coat of the stylet system were identified. The synthesis of the buccal–pharyngeal apparatus during molting was also analyzed obtaining a clear developmental sequence of its resynthesis. These findings lead us to redefine the previous interpretations of the functioning mechanisms of the buccal–pharyngeal apparatus and provide a more specific relationship between tardigrade diet and the anatomy of their feeding apparatuses. In addition, the detection by energy-dispersive X-ray spectroscopy of calcium in the stylets, buccal tube, and placoids of eutardigrade species (i.e., Milnesium tardigradum, Paramacrobiotus richtersi) indicates that CaCO3 incrustations are not an exclusive feature of heterotardigrades and lead to suppose that this trait was present in the ancestors of both classes.

The literature on terrestrial and freshwater Tardigrada is relatively limited, being concerned with 617 species world wide. Many of the references are in obscure publications. This paper attempts to bring this information together, tabulating the numbers of tardigrade species recorded from terrestrial and freshwater habitats in various countries and the number of countries from which tardigrades have been recorded. Each record is cross-referenced to the author in the references. It is hoped this paper will serve as a reference point and background for further zoogeographic studies.