Tardigrades of Finland: new records and an annotated checklist

Species checklists are powerful and important tools of communication between taxonomists and applied environmental biologists, which in turn lead to well-planned and successful conservation strategies and ecological studies. Despite this, only recently the interest on compiling systematic checklists is growing among taxonomists who study tardigrades-micrometazoans that inhabit almost every habitat worldwide. As the Finnish records of tardigrades (a.k.a. water bears) species are incomplete, outdated and no checklist has ever been compiled for this country, an easy-to-consult checklist is here reported. This checklist covers all Finnish tardigrade taxa identified in the past and in the 13 samples collected for this study. A total of 68 tardigrade species are recorded from Finland, with 6 of them being new records presented in this contribution. Of these species, four have their loci tipici in Finland and we provide an English translation of their original German descriptions. A Generalised Linear Model was used to test the effect of sampling effort and area size on the number of species recorded in each biogeographical province of Finland. The results showed that geographical differences in species richness can be explained solely by sampling effort. The number of tardigrade species recorded in Finland corresponds to about 5% of all described species in the phylum, thus indicating a potential high richness for this country. However, the results of the Generalised Linear Model highlight that a reliable knowledge of the tardigrade diversity in Finland will be reached only with a more uniform and intensive sampling effort.