STORAGE CELLS AND THEIR ROLE IN TARDIGRADE PHYSIOLOGY Abstract Tardigrades possess remarkable tolerance to numerous stress conditions (e.g. almost complete desiccation, exposure to very low sub-zero temperature, heat stress and even exposure to space in low Earth orbit). Indeed, they are among the most radiation-resistant multi-cellular organisms. The body cavity of tardigrades is filled with the storage cells (SC). Their role in anhydrobiosis has been discussed. The main objectives of this work were to analyse (i) the occurrence of mitosis in SC, (ii) the factors constraining anhydrobiotic survival, and (iii) the general ultrastructure of SC and their ultrastructure concerning the stress conditions. Our model species, R. cf. coronifer is one of the most extensively studied tardigrades concerning anhydrobiosis. Comprehensive histochemical techniques were used in combination with SEM, TEM, and confocal microscopy. First, mitotic divisions of tardigrade SC occur with a higher frequency in juveniles than in adults and correlate with animal growth. Mitosis is more frequent in moulting tardigrades, but the overall mitotic index is low. Furthermore, tardigrades of R. cf. coronifer can survive the maximum of 6 repeated desiccation cycles with significantly declining survival rate with repeated desiccations and...

Based on the original species descriptions, a review of the genus Paramacrobiotus was conducted. We divided the genus into two subgenera, Microplacoidus subgen. nov. and Paramacrobiotus subgen. nov., based on the presence or absence of a microplacoid, characterized species within the genus based on seven different types of eggs. In a moss sample collected in Ecuador, Paramacrobiotus (Paramacrobiotus) spinosus sp. nov., was found. The new species differs from all species of the subgenus Parama crobiotus by the presence of richtersi type eggs and from other species by morphometric characters. Additionally, in the Ecuadorian material we found P. (Microplacoidus) magdalenae comb. nov., which is the first record of this species in Ecuador, we provide the full set of measurements for this species, not included in the original description. An additional new record is P. (M.) alekseevi comb. nov. found in Vietnam for the first time. After examining microscope slides from the Iharos' collection deposited in the Hungarian Natural History Museum, we prepared re-descriptions of P. (P.) csotiensis comb nov., P. (M.) submorulatus comb. nov. and P. (M.) wauensis comb. nov. Based on the morphological and morphometric characters of adults and eggs, we developed a diagnostic key to the genus Paramacrobiotus.

Homeotherms and many poikilotherms display a positive relationship between body size and latitude, but this has rarely been investigated in microscopic animals. We analysed all published records of marine Tardigrada to address whether microscopic marine invertebrates have similar ecogeographical patterns to macroscopic animals. The data were analysed using spatially explicit generalized least squares models and linear models. We looked for latitudinal patterns in body size and species richness, testing for sampling bias and phylogenetic constraints. No latitudinal pattern was detected for species richness, and sampling bias was the strongest correlate of species richness. A hump-shaped increase in median body size with latitude was found, and the effect remained significant for the Northern Hemisphere but not for the Southern. The most significant effect supporting the latitudinal gradient was on minimum body size, with smaller species disappearing at higher latitudes. Our results suggest that biogeographical signals were observed for body size, albeit difficult to detect in poorly studied groups because of swamping from biased sampling effort and from low sample size. We did not find a significant correlation with the latitudinal pattern of body size and ecologically relevant net primary productivity.

The Fairy shrimp Branchinecta gaini Daday, 1910 is the largest freshwater invertebrate in Antarctica and the top-level consumer of local freshwater food webs. Ecological demands of B. gaini that are accompanied by 'ruderal' life strategy together with its spatial distribution that exceeds to Patagonia indicate that it had survived last glacial period in South America and expanded to Antarctica shortly after this epoch endeed. On James Ross Island that is the most extreme environment where B. gaini occurs today was this fairy shrimp considered extinct until year 2008. Its disappearance was based on paleolimnological analysis of several lake sediment cores according to which it inhabited this island between years 4200 to approximately 1500 before present when it died out because of changes in lake catchments caused by harsh neoglacial conditions. Paleolimnological analysis of Monolith Lake presented in this study has shown that this assumption was wrong and B. gaini has lived on James Ross Island throughout neoglacial period up to recent time. Phylogeographic analysis of 16S rDNA of specimens from Patagonia, South Orkneys, South Shetlands and James Ross Island revealed that its high morphological diversity is not supported by this gene and that all examined populations of B. gaini is one species with very few...

As part of the All Taxa Biodiversity Inventory (http://www.dlia.org), we are conducting a large-scale multihabitat inventory of tardigrades in the Great Smoky Mountains National Park (GSMNP) in Tennessee and North Carolina, USA. Here we report our findings for the genus Macrobiotus (Eutardigrada, Macrobiotidae). Two new species, Macrobiotus martini sp. nov. and Macrobiotus halei sp. nov., are described from moss, lichen, soil and leaf litter samples. Macrobiotus martini sp. nov. differs from all other species of the Macrobiotus hufelandi group by having a very simple buccal armature without bands of teeth, very large elliptical cuticular pores, unique characteristics of the egg, and other morphometric characters. Macrobiotus halei sp. nov. differs from other species in the Macrobiotus richtersi group by having very small cuticular tubercles, well-developed macroplacoids, unique characteristics of the egg, and other morphometric characters. Seven additional Macrobiotus species have been identified in the GSMNP: M. harmsworthi Murray, 1907, M. hufelandi Schultze, 1834, M. islandicus Richters, 1904, M, montanus Murray, 1910, M. pallarii Maucci, 1954, M. recens Cuénot, 1932, and M. tonollii Ramazzotti, 1956. All of these except M. harmsworthi are new records for the national park. In addition, M. pallarii is a new record for North Carolina, M. islandicus is a new record for North Carolina and Tennessee, M. montanus is a new record for the eastern USA, and M. recens is a new record for the USA.