William R. Miller

The use of HMDS (hexamethyldisilazane) to Replace Critical Point Drying (CPD) in the Preparation of Tardigrades for SEM (Scanning Electron Microscope) Imaging

HMDS (hexamethyldisilazane) may be used to replace the critical point drying step in sample preparation of tardigrades for SEM imaging. Previous procedures required a Critical Point Drying apparatus or machine to achieve the temperature/pressure combination to completely dehydrate a small specimen for SEM work. Now a simple bath in HMDS brings the specimens to the same state of dehydration without special equipment. Results are equal to the previous method.

Tardigrades of Alaska: distribution patterns, diversity and species richness

During the summer of 2010, a biotic survey of tardigrades was conducted along a latitudinal transect in central Alaska from the Kenai Peninsula, via Fairbanks and the Arctic Circle to the coastal plain. Work was centred at the Toolik and Bonanza Creek Long Term Ecological Research Network sites and supplemented by opportunistic collections from the Kenai Peninsula and Anchorage areas. The 235 samples collected at 20 sites over 10 degrees of latitude yielded 1463 tardigrades representing two classes, three orders, 10 families, 23 genera and 73 species from 142 positive samples. A total of 50 species are new to Alaska, increasing the states known species richness to 84. Several environmental metrics, such as pH, substrate, elevation, location and habitat were measured, recorded and analysed along the latitudinal gradient. Contrary to expectations, pH did not appear to be a predictor of tardigrade abundance or distribution. Density and species richness were relatively consistent across sites. However, the assemblages were highly variable within and between sites at only 14–20% similarity. We detected no correlation between species diversity and latitudinal or environmental gradients, though this may be affected by a high (59.9%) occurrence of single-species samples (containing individuals of only one species). Estimates of species richness were calculated for Alaska (118) and the Arctic (172). Our efforts increased the number of known species in Alaska to 84, and those results led us to question the validity of the estimate numbers.

Tardigrades of North America: Milnesium alabamae nov. sp. (Eutardigrada: Apochela: Milnesiidae) a New Species from Alabama

Milnesium alabamae nov. sp. is a new species of tardigrade described from Alabama, USA. This unique tardigrade of order Apochela and family Milnesiidae is characterized by its visibly punctuated cuticle, short, narrow buccal tube, and long primary branch of the claws without accessory points. The buccal tube appears to be only half the length of the signature species Milnesium tardigradum for animals of similar body length. The specimens add data to the questions of tardigrade distribution and evolution.

Tardigrades in the canopy: Using double rope techniques to conduct sampling along vertical transects

The methods called Double-rope techniques (DRT) were used to sample vertical transects into the temperate forest canopy, to determine the diversity and abundance of tardigrades. This technique is reputedly the safest method of accessing canopies and it uses a minimum of technical hardware. In this case, DRT served to facilitate the access of mobility-limited students into the forest canopy, thereby providing an inspiring experience in field biology for this underserved group as well as allowing replicated point sampling of organisms throughout the treetops.

Tardigrades of North America: Oreella chugachii, a new species (Heterotardigrada, Echiniscoide, Oreellidae) from Alaska

Abstract A new species of tardigrade in the genus Oreella (Heterotardigrada, Echiniscoide, Oreellidae) is described from Girdwood, Alaska, U.S.A., North America. Oreella chugachii, new species, has single granulation, a short cirri A, and a small primary clava. The pharyngeal tube is long and flexible, eyes may be present, and the eggs have small pointed tips on their projections. In addition, a segment of the 18s rDNA gene is filed with GenBank as part of the description. The discovery in the northern hemisphere of a population of a new species of Oreella, a previously monotypic, Gondwanian genus, expands the biogeography of what is believed to be a foundation group for limno-terrestrial tardigrades.

Are urban and rural tardigrade (Tardigrada) communities distinct and determined by pH: A case study from Fresno County, California

Abstract Tardigrades were collected from 73 urban sites and 24 rural locations in Fresno County, California to determine if differences existed in community structure between the two environments. Only 22 percent of urban samples were positive for tardigrades, as compared to 74 percent of rural samples. Samples from urban sites contained significantly fewer species than rural sites, although the average density did not vary significantly between urban and rural sites. Twenty-six different species were identified, with seven exclusively in the urban samples, 16 found only from rural samples, and three species found in both environments. Similarity analysis indicated urban communities were more similar to one another compared to similarities among rural communities, indicating significant differences between urban and rural communities. Tardigrades appeared to prefer habitat with a lower pH in both urban and rural locations. While our findings do support the negative relationship between urban sites and tardigrade richness, it was not explained by the lower pH typically associated with urban habitats. Further, we identified two species of Isohypsibius not previously recorded in the Western Hemisphere. The genus Eremobiotus was found for the first time in the Americas, and a species of Ramazzottius for the first time in North America.

Do Water Bears Climb Trees Too

Microinvertebrates are those animals on the edge of invisibility, generally requiring a microscope to see. They include mites, rotifers, nematodes, and tardigrades and form an unseen part of the food web. These animals eat smaller organisms (bacteria, algae, and protozoans,) and are eaten by larger ones (mites, insect larva, insects, or each other). In turn, they are consumed by the animals that graze on their habitat of moss and lichen. But their habitat is threatened by logging, burning, air pollution, and global warming. Edge effect and forest islands are increasing, as are average temperatures. It is clear that the underlying habitat for microinvertebrates (moss, lichen, and algae on trees) must also be declining and changing and the formula for the survival of these invisible components of the canopy ecosystem is being altered. It is unclear if the microinvertebrates can or will be able to change as the paradigm for their survival shifts. If not, they might be the weak link in the productivity of forest ecosystems.

Tardigrades of the University of Central Arkansas Campus, Conway, AR

Abstract Tardigrades were recovered from samples of moss and lichen growing on the bark of seven species of trees on the University of Central Arkansas (UCA) campus in Conway, AR. Of the 11 genera of tardigrades previously reported from the state, five were found in the UCA campus samples; of the 25 species previously reported, five were found in the UCA campus samples. Two species (Milnesium eurystomum, Macrobiotus polyopus) are new records for the state; one species of Echiniscus (arctomys group) could not be identified and may be new. Tardigrades were not uniformly distributed among available habitats (moss, lichen) or substrates (trees).

Tardigrades of the Canopy: Doryphoribius gibber Beasley and Pilato, 1987 (Eutardigrada: Parachela: Hypsibiidae) New Records from Eastern Kansas, U.S.A.

The geographic distribution of tardigrade species across the planet is poorly known, and certainly incomplete. While some species appear to be cosmopolitan, published data still shows most species with spotty and disjointed distributions, due to the lack of detailed, expansive diversity studies. This report adds to the biogeography and habitat of Doryphoribius gibber Beasley and Pilato, 1987. Known previously only from ground level moss in Arkansas, U.S.A. and Chiapas, Mexico this species has now been found 290 km further north, in both moss and lichen habitats in the canopy of the deciduous forest of northeastern Kansas, U.S.A

Tardigrades of North America: further description of the genus Multipseudechiniscus Schulte & Miller, 2011 (Heterotardigrada: Echiniscoidea: Echiniscidae) from California

Abstract This article contributes the descriptive detail for Multipseudechiniscus Schulte & Miller, 2011, a new genus in the family Echiniscidae named but incompletely described in the recent publication of a poster abstract. Multipseudechiniscus was separated from Pseudechiniscus based on the presence of paired pseudosegmental plates on each trunk segment; a long, flexible pharyngeal tube; and large spurs on the internal claws. The type species, Pseudechiniscus raneyi (Grigarick, Mihelćić, & Schuster, 1964) is re-described. The new genus has been collected only in California, Oregon, and Montana, U.S.A. and appears to have a regional distribution.