Systematics, palaeontology and ultrastructure of tardigrades
A review of the tardigrade fauna of Australia, based on new collections made in 1995-96, has been completed (R.M. Kristensen, with S. Claxton, Macquarie University, Sydney). The tardigrade fauna of the Himalayas has been investigated and a new black heterotardigrade described from more than 6000m altitude (R.M.Kristensen, with H. Dastych, Zoologisches Museum, Hamburg). A study of spermiogenesis in the arthrotardigrade Actinarctus doryphorus has been initiated (R.M. Kristensen, with A. Jørgensen and N. Møbjerg, Zoological Institute). A review paper on the ultrastructure of the cuticle of marine tardigrades has been completed (R.M. Kristensen, with B. Neuhaus, Museum für Naturkunde, Berlin).
A study on the life in cryoconite dust from the ice cap of Greenland has been completed. Six species of eutardigrades were found living permanently in the cryoconite holes, and one species was found in ice-moulin down to 110 m (A. Grøngaard, cand. scient. project).
A study on the phylogeny of the family Echiniscidae has been initiated (A. Jørgensen).
New techniques in palaeontology have uncovered an ancient meiofauna. SEM-studies on a tardigrade/lobopod stem group species from an about 535 mio-years-old Siberian limestone have been carried out (R.M. Kristensen, with D. Walossek, University of Ulm and C. Müller, Rhenische Friedrich-Willems-Universität, Bonn).
Field and laboratory studies on the tardigrades Halobiotus crispae and Echiniscoides sigismundi were conducted in 1992-1995 for the project "Ultrastructural studies on the embryology and ontogeny of Tardigrada, with particular reference to the pharynx". The purpose of the study was to generate information relevant to the discussion about the phylogenetic position of the group. The principal results were: 1) Early cleavages are total and equal, and there possibly is a resemblance with the spiral pattern; it seems that the mesoderm is formed at an earlier stage than reported in the literature. 2) The pharynx of H. crispae exhibits eutely, and each cell has been identified and its ontogeny and ultrastructure described; a hypothesis for the function of the pharynx has been proposed. 3) The pharynx is an ectodermal myoepithelium* (J. Eibye-Jacobsen, ph.d. project).