Rediscovering the diversity of Brazilian limno-terrestrial tardigrades

Tardigrades are aquatic microinvertebrates (generally they measure 0,05-1,2 mm) that feature four pairs of telescoping legs terminated in claws or digits and a have fairly characteristic buccal apparatus. They are known due to their ability to undergo cryptobiosis, an extremely environmentally resistant state. Despite this, little is know about the diversity and distribution of the phylum Tardigrada, mostly due to the small size and the fragility of their bodies, that require specific handling and laboratory instruments. In Brazil the limno-terrestrial tardigrades were not studied since the pioneers studies in the decades of 1940 and 1950. The present study aims to describe a new species of the genus Milnesium (class Eutardigrada, order Apochela, family Milnesiidae), collected from trees in the Institute of Biology, University of Campinas, Sao Paulo, Brazil, using modern morphological techniques, such as morphometrics, differential interference contrast (DIC) microscopy, scanning electron microscopy (SEM), and UV autofluorescence. This Milnesium sp. nov. is characterized by its smooth cuticle, six peribuccal lamellae of unequal size, short cuticular bars under the claws IV, a claw configuration of [3-3]-[3-3] with internal and anterior spurs larger than external and posterior spurs, and pseudoplates on the dorsum.