Preliminary data on tradigrades of Lake Biwa (Japan) (original) (raw)
Related papers
Zoological Science, 2007
A new freshwater tardigrade species, Pseudobiotus spinifer sp. nov., is described from the sand bottom of Nakdong River, South Korea. The new species is most similar to Pseudobiotus vladimiri from Biwa Lake, Japan, but differs from it by having small accessory points ending in the center of the primary branches of all claws, relatively longer claws and macroplacoids, and well developed cuticular spines/spicules over most of the dorsal and lateral surfaces of the body. Pseudobiotus vladimiri is redescribed on the basis of the holotype. A revised key to the species of the genus Pseudobiotus is also given.
Nearctic freshwater tardigrades: a review
Journal of Limnology, 2007
The distribution and ecology of limno-terrestrial Tardigrada in the Nearctic realm remain poorly known. This is especially true of freshwater tardigrades (i.e., species found in permanently submerged habitats), which have received much less attention than terrestrial species. We reviewed the literature on Nearctic freshwater tardigrades. Of 204 Nearctic limno-terrestrial tardigrade species, 44 have been collected from sediments and aquatic vegetation of streams, rivers, ponds, lakes, groundwater and cryoconite holes. Of these, 17 are hydrophilous species found exclusively or primarily in aquatic environments. Most of the remainder are probably washed in accidentally from terrestrial substrates. Among the hydrophilous species, five are endemic to the Nearctic realm and three cosmopolitan. Hypsibius dujardini is the most widely-distributed hydrophilous species. There are no regional collections of Nearctic freshwater tardigrades comparable to those for terrestrial species. Aquatic tardigrades are benthic, and are found in sediments and on aquatic vegetation. Hypsibius dujardini and other widespread species are found in both substrates, and there is thus no evidence of substrate specificity. Numerically, tardigrades usually comprise a minor component of benthic invertebrate communities. Nothing is known of their trophic relationships or dispersal in these habitats. The density of Nearctic freshwater tardigrade species peaks in the spring and/or fall. Future research should increase the spatial and temporal scale of study, and employ adequate replication.
Global diversity of tardigrades (Tardigrada) in freshwater
Hydrobiologia, 2008
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.
A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada)
Zootaxa, 2017
This is an identification guide to the 47 currently described genera of marine heterotardigrades. We provide clear definitions and illustrations of relevant anatomy and an easy to use dichotomous key. The aim of the present contribution is to enable more people to identify collected specimens of marine heterotardigrades, and hopefully, encourage more people to study this intriguing group of animals. The paper is divided into three parts. The first part gives a brief introduction to heterotardigrade morphology with special emphasis on taxonomically important characters. The second part is the actual key, which is accompanied by illustrations of both habitus and detailed foot morphology of the marine heterotardigrade genera. The third part provides up to date diagnoses of the orders, families, subfamilies and genera of marine heterotardigrades according to the most recent emendments. With the generic diagnoses, we provide a bibliography with selected literature that relates to each specific genus.
Current Status of the Tardigrada: Evolution and Ecology
Integrative and Comparative Biology, 2002
The Tardigrada are bilaterally symmetrical micrometazoans with four pairs of lobopod legs terminating in claws or sucking disks. They occupy a diversity of niches in marine, freshwater, and terrestrial environments throughout the world. Some have a cosmopolitan distribution, while others are endemic. About 900 species have been described thus far, but many more species are expected as additional habitats are investigated. Most are less than 1 mm in body length and are opaque or translucent, exhibiting colors such as brown, green, orange, yellow, red, or pink in the cuticle and/or gut. Marine species are more variable in body shape and overall appearance and generally exhibit low population density with high species diversity. Reproductive modes include sexual reproduction and parthenogenesis, but much remains to be known about development. Tardigrades have a hemocoel-type of fluid-filled body cavity, a complete digestive tract, and a lobed dorsal brain with a ventral nerve cord with fused ganglia. Recent molecular analyses and additional morphological studies of the nervous system have confirmed the phylogenetic position of tardigrades as a sister group of the arthropods. The ability of tardigrades to undergo cryptobiosis has long intrigued scientists. Although tardigrades are active only when surrounded by a film of water, they can enter latent states in response to desiccation (anhydrobiosis), temperature (cryobiosis), low oxygen (anoxybiosis), and salinity changes (osmobiosis). Cryptobiotic states aid in dispersal.
Tropical Zoology, 2001
Five species of tardigrades from South America are recorded, two of which, Pseudechiniscus spinerectus and Macrobiotus danielae, are new to science, and one, Doryphoribius flavus (Iharos 1966), is new for South America. Pseudechiniscus spinerectus differs from P. bidenticulatus Bartos ⁄ 1963 and P. bartkei Weglarska 1962 by having median plate 2 divided into two portions, spines of the pseudosegmental plate more developed; it differs from P. bidenticulatus by having inner claws with a spur; it differs from P. bartkei by having the caudal portion of the scapular plate faceted, more dense plate sculpture with dot size increasing from the head to the terminal plate, striae joining the dots to each other less evident. P. spinerectus differs from P. ramazzottii Maucci 1952 and from P. brevimontanus Kendall-Fite & Nelson 1996 in the following features: spines of the pseudosegmental plate more developed, dots of plate sculpture joined to each other by striae. It differs from P. ramazzottii also by having the papilla of the hind legs clearly shorter; it differs from P. brevimontanus also for some details of the ventral cuticular sculpture. Macrobiotus danielae belongs to the richtersi-group; it is very similar to Macrobiotus vanescens Pilato et al. 1991 from which it differs in the following features: smaller body size, wider buccal tube, slightly longer microplacoid, more slender claws, some characters of the eggs (reticular sculpture of the conical processes with less prominent ridges; less evident apical indentation; basal areolae smooth).
Invertzool
This study considers in a new light a population already studied and tentatively attributed to Macrobiotus cf. terminalis (Bertolani, Rebecchi, 1993), by joining molecular approaches to the traditional, but indispensable, light microscopy, and to scanning electron microscopy. Differences in animal and, above all, egg shell morphology, and the peculiar cox1 sequence indicate that this population clearly pertains to a new species, M. vladimiri sp.n., which is here described. The results obtained can be considered as an example of how a modern taxonomical and biogeographical research can be carried out on this animal phylum and in general on the animals belonging to the so called meiofauna, where characters bound to morphology are often very few. This is the first tardigrade species to be described and barcoded contemporarily.
An Introduction to phylum Tardigrada -Review
Tardigrades popularly known as water bears are micrometazoans with four pairs of lobopod legs. They are the organisms which can live in extreme conditions and are known to survive in vacuum and space without protection. Tardigardes survive in lichens and mosses, usually associated with water film on mosses, liverworts, and lichens. More species are found in milder environments such as meadows, ponds and lakes. They are the first known species to survive in outer space. Tardigrades are closely related to Arthropoda and nematodes based on their morphological and molecular analysis. The cryptobiosis of Tardigrades have helped scientists to develop dry vaccines. They have been applied as research subjects in transplantology. Future research would help in more applications of tardigrades in the field of science.
Transactions of the American Microscopical Society, 1989
A new interstitial arthrotardigracie, Paradoxipus orzeliscoides n. gen., n. sp., is described from subtidal coarsc-.s,Jnd and shell-hash habitats, at 15 m depth, 8.4 km east of Fort Pierce, Florida, and from txiedium-sand of the dredged channel, 5 m depth, of the Intracoastal Waterway of the Indian River, north of Fort Pierce. The new species is distinguished by the presence of both suction discs and claws on the toes, two pairs of clavae, and pointed lateral and caudal alae. Interference-contrast optics were used to videorecord living specimens of the new species in order to study the functional morphology of the suction discs. Comparisons of the legs of Orzeliscus and Paradoxipus a. gen. were made. The phylogenetic relationships of the new genus to other genera in Halechiniscidae and Orzeliscidae are discu.s.scd. On the l)asis of characters shared with Chrysoarctus, Paradoxipus is assigned to the subfamily Halecfiiniscinai-. Complex seminal receptacles and two pairs of clavae in the new genus are considered plesiomorphic characters, and suction discs and transparent alae are considered apomorphous ones.