Abstract
The paper is a systematic account of the macrodasyidan gastrotrichs of the Tromsø region, northern Norway, collected in 1969 and 1992. Twenty-nine species (six new and three left in open nomenclature) representing all the six macrodasyidan families, are described or recorded. One new species, Desmodasys boreaiis sp. nov. is described in the family Turbanellidae, and five new species, Acanthodasys lineatus sp. nov., Tetranchyroderma arcticum sp. nov., Tetranchyrodenna boreale sp. nov., Tetranchyroderma bulbosum sp. nov., and Ptychostomella lepidota sp. nov., are described in the family Thaumastodermatidae. Desmodasys borealis is the second described species in the genus, and like its sibling, D. phocoides Clausen, 1965, which is known only from Bergen, Norway, inhabits coarse gravel of organic origin in exposed areas. All the other new species were found in less exposed places in medium to coarse sediments. Additionally follows a report with a photomicrograph of an undescribed species of Lepidodasys from Ischia, Italy.
