Seasonal and Altitudinal Variation in the Distribution and Abundance of Tardigrada on Dugger Mountain, Alabama

A seasonal survey of the distribution of terrestrial tardigrades on Dugger Mountain, Alabama, was conducted during the time period from April 1997 through April 1998. Cryptogams from five trees (Quercus alba), three on north-facing slopes and two on south-facing slopes, were sampled seasonally at three stations (645 m, 410 m, 183 m) along an unnamed tributary of the South Fork of Terrapin Creek. Trees were chosen based on their location outside the riparian zone. Tardigrades were extracted from the samples, mounted individually in Hoyer's medium, and identified to species with phase microscopy. Seasonal and altitudinal variations in the distribution of the populations on the north- and south-facing slopes were determined. Present on Dugger Mountain were tardigrades belonging to 12 species (Macrobiotus cf. areolatus/tonollii, Macrobiotus cf. echinogenitus, Macrobiotus islandicus, Macrobiotus richtersi, Minibiotus intermedius, Milnesium tardigradum, Diphascon pingue, Hypsibius pallidus, Echiniscus cf. arctomys, Echiniscus virginicus, Pseudechiniscus ramazzottii, and Pseudechiniscus suillus). Due to the small numbers of individuals of each species, the total numbers of tardigrades of all species were pooled. There were no significant differences in the mean number of species or the mean number of all tardigrades per sample at each station (altitude). However, seasonal differences in both abundance and number of species were detected in pooled samples due to the high numbers collected in spring 1997.     

Two new species of tardigrades from Short Mountain, Tennessee, U.S.A.

Tardigrades were collected from three seepage spring sites at 549m on Short Mountain, Cannon County, Tennessee. Three terrestrial samples and three aquatic samples were taken monthly from each site. Terrestrial samples included mosses and lichens from rocks and fallen trees; one sample of leaf litter was also collected from two of the sites. Aquatic samples included sediment, decaying leaf litter, and aquatic plants. Specimens of tardigrades were mounted on individual slides in Hoyer's medium. Species were identified and photographed using phase and differential contrast microscopy. Twenty-eight species representing 13 genera were recorded: Pseudechiniscus, Echiniscus, Doryphoribius, Ramazzottius, Hypsibius, Isohypsibius, Dipliascon, Platicrista, Itaquascon, Murrayon, Macrobiotus, Minibiotus , and Milnesium. One of the Pseudechmiscus species and an Isohypsibius species were new to science and are described in this paper.     

The tardigrades of Emilia (Italy). II. Monte Rondinaio. A multihabitat study on a high altitude valley of the northern Apennines

We investigated a small valley of glacial origin in the northern Apennines (Italy). A multihabitat study was performed on the mosses and lichens on rocks, temporarily submersed mosses, beech litter, grass turf and sediments from pools, ponds and streams. A few species colonized more than one habitat. Several species were typical of high altitudes or latitudes, some were rare, and two, Hypsibius pradellii sp. nov. and Diphascon (Diphascon) secchii sp. nov. , were new to science.     

Population density and species composition of moss-living tardigrades in a boreo-nemoral forest

This study investigates for the first time the tardigrade fauna in a variety of different mosses from a coniferous forest and an adjacent clear-cut area in southern Sweden. Tardigrades were found in a majority of the samples. Sixteen species were recorded, of which the cosmopolitan species Macrobiotus hufelandi was the far most common. Some mosses, particularly species with "wefts" growth form, contained more tardigrades than other mosses, indicating that growth form may have an impact on tardigrade abundance. Mosses of the same species collected from a forest and from a clear-cut, respectively, did not show a general trend in the overall abundance of tardigrades, but the forest tended to contain more species. Five species of tardigrades ( Murrayon dianae, Isohypsibius sattleri, Platicrista angustata, Diphascon belgicae and Diphascon pingue ) never previously reported from Sweden were recorded.     

中国缓步动物门一新亚种及两新纪录种记述

报道了我国缓步动物门1新亚种Diphascon(Adropion)scoticum qinlingensis subsp.nov.和中国2新纪录Rictersius coronifer ( Richters, 1903) (Eutardigrada, Macrobiotidae)和 Diphascon scoticum Murray, 1905 (Eutardigrada, Hypsibiidae).新亚种主要以爪的主枝基部极度收缩区别于世界其他产地的标本(指名亚种).新亚种和新纪录均采自秦岭山区.     

Spermatozoan morphology as a character for tardigrade systematics: comparison with sclerified parts of animals and eggs in eutardigrades

The male gamete, a cell widely used for evaluating phylogeny in different animal groups, remains relatively unknown in tardigrades. In this paper the spermatozoa of thirteen species of eutardigrades among four genera and three families is evaluated in order to determine whether sperm morphology can be used as a taxonomic character. Spermatozoa of Amphibolus volubilis and A. weglarskae are very similar and this resemblance is congruent with the remarkable similarity of sclerified parts of the species. In addition, the spermatozoa of eight species of the genus Macrobiotus were examined yielding two groups showing strong intragroup similarities. The first group includes M. pseudohufelandi, M. sandrae, M. macrocalix, M. terminals and M.joannae , and the second M. richtersi, M. areolatus and M. harmsworthi. Again, these groupings were congruent with those determined by analysis of sclerified structures. In contrast, a marked similarity was found between the spermatozoa ot Diphascon (Adropion) scoticum and Platicrista angustata , whereas Diphascon (Diphascon) humicus was appreciably different from both species. Resemblances found in this study between spermatozoa and sclerified body parts suggests that the spermatozoa are suitable characters for use in systematic studies.     

Tardigrades of the Taimyr peninsula with descriptions of two new species

This is the first report on tardigrades from the Taimyr peninsula. Seventy-one species of tardigrades were recorded, new to Russian fauna and two of which are new to science. Diphascon boreale sp. nov. is closely related to D. brevipes (Marcus, 1936) but easily distinguished from it by claw structure and the absence of cuticular bars on the legs. Isohypsibius roberti sp. nov. belongs to the elegans group of the genus Isohypsibius ; it diners from other species in the group by having a long and thin buccal tube and large lunulae with small teeth on leg IV. The eggs of Ramazzottius montivagus are here described for the first time. The almost complete absence of tardigrades in and around Norilsk is noted. This is related to the heavy industrial pollution from a local nickel-copper plant.     

A survey of the terrestrial Tardigrada of the Vestfold Hills,Antarctica

A survey of the terrestrial tardigrades inhabiting growths of algae, lichens and mosses in the Vestfold Hills, Antarctica, was carried out at 11 and 35 sites during the austral summers of 1980 and 1982, respectively. In all, 24 species of plants were collected from which four genera and four species of Tardigrada were recovered. A key to the tardigrades of the area is presented. The distribution and associational patterns of the tardigrades are discussed in the context of other studies of antarctic Tardigrada.     

Factors influencing the distribution of aquatic plant communities in Irish canals

Terrestrial tardigrades are often found in the lichens and mosses growing on trees and rocks. The assertion that tardigrades in these habitats are very patchy in their distribution has rarely been backed by quantitative sampling. This study assesses spatial variability in tardigrade populations inhabiting small patches (0.1 cm² to over 5 cm²) of moss and lichen on trees and rocks at three sites in the United States of America. Tardigrades were collected from four replicate rocks in the Ouachita Mountains of Arkansas, with 30 lichen patches collected on two adjacent boulders and 20 moss patches on a second pair of boulders. In Fort Myers and in Citrus Springs, Florida, 30 lichen patches per tree were collected from two pairs of trees. The tardigrades in each sample were extracted, mounted, identified, and counted. The variation in tardigrade abundance among lichen or moss patches within rocks or trees was very high; the only consistent pattern was that very small patches usually lacked tardigrades. Tardigrade diversity and abundance also varied greatly within sites when lichens and mosses of the same species from different rocks and trees were compared (in the most extreme case one tree had numerous individuals of two tardigrade species present while the other had almost no tardigrades). The results of this quantitative sampling support the assertion that tardigrades are very patchy in distribution. Given the considerable time investment required for the quantitative processing of tardigrade samples, this high spatial variability in tardigrade diversity and abundance requires that researches testing ecological hypotheses about tardigrade abundance check variability before deciding how many samples to take.     

The significance of four xeric parameters in the ecology of terrestrial Tardigrada

Tardigrades were sampled from diverse biotypes and classified according to four xeric variables to assess susceptibility to desiccation: exposure to insolation, elevation, and standardized desiccation rate and hydration capacity of the habitat plant. Fifteen tardigrade species were recorded including Hypsibius cataphractus Maucci, a new addition to the British fauna.
Xeric associations with seven tardigrade species were analysed by multiple regression, using incidence and population density as independent abundance estimates. Species show considerable variation in ecotype. The hygrophilic Macrobiotus hufelandi and Hypsibius dujar dini are excluded from rapidly desiccating habitats. Xerophiles, Milnesium tardigradum and H. oberhaeuseri , do not favour high insolation or high desiccation rate but apparently shun poorly drained sites and/ or prolonged hydration. Significant interspecific associations are identified between Milnesium tardigradum and two Hypsibius species which it may exploit for food. Negative associations between three other species— M. hufelandi, M. richtersi and H. prosostomus —suggest competitive exclusion.
The interstitial meiofauna of a dehydrating moss cushion migrates vertically to the proximal C-zone, although this behaviour is not observed in Echiniscus testudo; implications of this for the species' ecotype are discussed.     

Genome size variation in Tardigrada

The genome size of tardigrades has been documented to date in seven species of eutardigrades, and it is among the lowest in invertebrates. In this paper the evaluation of genome size is extended to eight other speeies of eutardigrades and to one species of heterolardigradcs, in order to obtain a more comprehensive picture of minimum DNA content evolution in this phylum. The genome size of the heterotardigrade Pseudechiniscus juanitae (0.6 pg), measured using le cells, is found to resemble that of some eutardigrades. Thus, it is not possible to discriminate between the two classes of tardigrades on this basis. Literature and new data on eutardigrades also suggest that families or subfamilies cannot be discriminated on the basis of genome size. Nevertheless, genome size and sperm cell shape are correlated. A lower DNA content always corresponds to a more specialized male gamete. In general, in tardigrades, the low genome size and its low variation could be related to the high specialization of the phylum. Preliminary data on nuclear AT contents suggest that the variations in those values are correlated with genome size variations.     

Interspecific Association and Substrate Specificity in Tardigrades from Florida, Southeastern United States

The distribution of terrestrial tardigrades in the Gulf Coast states of the United States is poorly known. Only one species has been reported in Florida. In this study moss, liverwort, lichen and fern samples (47 identified species) from trees and shrubs were collected from all 67 Florida counties. These samples contained 20 species of tardigrade. All possible pairs of tardigrade species and tardigrade and substrate were tested for interspecific association. Only three significant negative and one positive interspecific association between tardigrades were detected. Evidence for substrate specificity was weak. Although some tardigrade species were significantly associated with mosses or foliose lichens in general, no significant association between a tardigrade species and a substrate species was detected.     

A new species of the genus Hypsibius (Tardigrada: Parachela: Hypsibiidae) from Sakhalin island, far East Russia

A new species of semiterrestrial eutardigrade, Hypsibius stiliferus, is described from Sakhalin Island, Far East Russia. The new species is distinguished from its congeners by having an irregular, polygonal or subtriangular dorsal sculpture, which increases in size posteriorly, two granular macroplacoids, and a cuticular bar near the base of posterior claw 4, and by lacking a microplacoid and septulum. It is currently known from its type locality and several other localities in northern and southern Sakhalin Island. This is the first report concerning tardigrades from Sakhalin Island.     

The Tardigrades of Emilia (Italy). III. Piane di Mocogno (Northern Apennines)

Samples of leaf litter, mosses and lichens were collected in a beech forest at Piane di Mocogno (Emilia, Italy), 1200 m asl. The tardigrade community of the leaf litter was similar to that found in this substrate in Italy and in the U.S.A. At Piane di Mocogno the species association within the leaf litter was different from that in mosses and lichens (which have similar fauna), confirming that very different communities characterise different substrates such as leaf litter and mosses. During this faunal analysis, six species of tardigrades were found for the first time in this area. The presence of Microhypsibius bertolanii (first record in leaf litter and in Italy) and Eohypsibius nadjae are note worthy. Ornamented eggs in an exuvium of Hypsibius cf.scabropygus were also recorded for the first time.     

The association of oribatid mites with lichens

Oribatei (Acari, Cryptostigmata) are found in a variety of terrestrial habitats, and many are associated with lichens; the relationship ranges from casual to highly dependent. Eighty-three species associated with lichens have been surveyed, and a tentative classification, based on their ecological requirements, is presented: Group A consists of species restricted to lichens as a biotope, though occasionally occurring as accidentals in other habitats; Group B consists of species which while preferring lichens as a habitat and feeding source are also adapted to existence on other plants (though in some cases their immatures may be lichen-restricted); Group C consists of species which, though frequently found on lichens, are equally common in other biotopes, particularly mosses, and must be regarded as much more generalized in their feeding habits. Certain aspects of oribatid-lichen specificity are discussed. The importance of oribatid-lichen associations from the point of view of soil fertility and energetics is emphasized.     

Tardigrades of Louisiana and Arkansas, United States of America

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.     

Tardigrade Fauna of the Region between Oka and Volga Rivers (Russia) and Patterns of their Distribution in Substrates and Habitats

The region between the Oka and Volga rivers has been largely neglected with respect to tardigrade biodiversity. In the present study a total of 21 species from 7 genera, 3 families, 2 orders and only 1 class of tardigrades were present, and some of their ecological preferences were noted. The tardigrades in the studied region were mainly cosmopolitan. Eurytopic, hygrophilic and xerophilic species were common while obligate freshwater species were not found. There is a marked similarity in the tardigrade fauna within similar habitats from different locations within the region.     

Tardigrades of South America: Machu Picchu and Ollantaytambo, Peru

During July 1999, a study group from the University of Kansas visited the ancient Inca ruins in and around Machu Picchu and Ollantaytambo, Peru. They collected lichens and mosses from the rock walls around the ruins. The samples contained four genera and six species of tardigrades. No associational patterns and relationships were detected. A new species, Echiniscus ollantaytamboensis nov. sp. is described.