Tardigrade taxonomy: an updated check list of the taxa and a list of characters for their identification

Abstract

Since the most recent monograph on Tardigrada by Ramazzotti & Maucci (1983), many changes have been introduced in the systematics of this phylum which has gone through different revisions and has been expanded by several new taxa. Moreover, the number of species is considerably increased (almost doubled to more than 960 species) and new families and genera have been created, while many taxa have been amended. The difficulty in finding a complete, updated list of taxa and the problems with putting together all the newly proposed taxonomic criteria, led us to compile an updated list of tardigrade taxa. This list is supplemented by a series of bibliographic references inherent in the synonymies and/or the amended diagnosis of the taxa occurred after 1983, and a list of the main characters used in the diagnosis of the species. These lists are aimed at helping not only the specialists studying this group, but also researchers interested in biodiversity and those who have to refer to this animal group.

3-Dimensional reconstruction of fluorescent structures in tardigrades

“…All characters of taxonomic importance can be revealed on this single specimen irrespective of their position. That way the method is certainly valuable for taxonomic work and results in didactically valuable 3D models of taxonomically important characters (Miller 2004;Guidetti & Bertolani 2005). In comparison or opposition to scanning electron microscopy the preparation for the described method is less laborious, thus faster, and this light-microscopical method produces 3D reconstructions that also reveal their covered side "underneath" because they can be turned around after reconstruction (Eibye-Jacobson 2001).…”

“…The claws and bucco-pharyngeal apparatuses of eutardigrades are, among others, important taxonomic structures (Ramazzotti & Maucci 1983;Guidetti & Bertolani 2005) that show convenient autofluorescence in green and red light after excitation with blue and green light respectively. The autofluorescence intensity is significantly high, enabling its clear detection above the diffuse background autofluorescence of the tardigrade's body.…”

“…Tardigrades are microscopic small animals within their own phylum consisting of more than 960 species (Nelson 2001;Maas & Waloszek 2001;Guidetti & Bertolani 2005). The first occurrence of tardigrades is reported from the mid Cambrian (Müller et al 1995).…”

“…The animals bear a chitinous cuticle and their taxonomy mainly refers to their claws, the bucco-pharyngeal apparatus, the cuticle`s structure as well as to appendages of the cuticle (Thulin 1928;Ramazzotti 1962;Pilato 1969Pilato , 1975; Guidetti & Bertolani 2005). Whilst all these characters are examined microscopically, and brightfield illumination techniques are well established for tardigrade examination, tardigrades are still said to be difficult objects for fluorescence microscopy (Russell et al 2001).…”

Identification of the trehalose-6-phosphate synthase (tps) gene in desiccation tolerant and intolerant tardigrades

“…Animals were extracted from the substrates by means of sieves and picked up with a glass pipette under a stereomicroscope. Each individual tardigrade analyzed was previously observed in vivo under light microscopy and identified according to its morphological characters (Guidetti & Bertolani 2005;Pilato & Binda 2010). Analyses were carried out with a Leitz DM RB microscope, using differential interference contrast (DIC) with the 40x objective and the 100x oil objective.…”