Tardigrades of Finland: new records and an annotated checklist

Abstract

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 As the Finnish records of tardigrades (a.k.a. water bears) species are incomplete, outdated and no checklist has ever been compiled for this country, an easy-to-consult checklist is here reported.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.

Integrative taxonomy resolves species identities within the Macrobiotus pallarii complex (Eutardigrada: Macrobiotidae)

“…Specifically, biodiversity studies and taxonomic checklists need precise taxonomic identifications to be comparable across different geographical areas. However, as noted, e.g., by [ 82 ], numerous identifications cannot be confirmed due to the presence of (pseudo) cryptic species complexes. Furthermore, biogeographical studies supported by molecular data on tardigrades are still scarce.…”

“…Species of the Macrobiotus pallarii complex are not commonly found, but the complex has a wide, possibly global distribution. Although the majority of records are concentrated in Europe (Finland, Greece, Hungary, Italy, Montenegro, Norway, Poland, Republic of Bulgaria, Russian Federation, Turkey, Yugoslavia [ 25 , 82 , 96 – 98 ]), there are also reports from Asia (North Korea, Russian Federation [ 25 ]), North America (United States, Cayman Islands [ 28 , 86 – 88 ]), and Africa (Democratic Republic of the Congo, Swaziland [ 27 , 92 ]). In light of our findings, all these records except the type localities should be considered dubious and be designated as species of the Macrobiotus pallarii complex, i.e., as Macrobiotus aff.…”

Tardigrades of Kristianstads Vattenrike Biosphere Reserve with description of four new species from Sweden

“…Other faunistic studies, comparable in sampling effort and substrate diversity, found lower diversity, e.g. 26 species in 32 samples, ratio 0.81 (Marche-Umbria, Italy) 61 , 23 species in 48 samples, ratio 0.47 (Sardinia, Italy) 62 , 41 species in 60 samples, ratio 0.68 (Great Smoky Mountains National Park, TN-NC, USA) 60 , 10 species in 13 samples, ratio 0.76 (Jyväskylä, Finland) 58 . Therefore, this study indicates a high biodiversity of tardigrades in the KVBR, as suggested by the presence of many genera, species, and new taxa from different environments and habitats (i.e.…”

“…The species abundance of tardigrades has been shown to be mostly related to the sampling effort, rather than to the surface of the sampling area 58 . The limited number of visited sites and limited sampling effort (34 samples collected in five sites of a 1050 km 2 area) of our study suggest that the true tardigrade biodiversity of KVRB is much higher than recorded, and that there are considerably more tardigrade species to be found in this area.…”

Integrative descriptions of two new Macrobiotus species (Tardigrada, Eutardigrada, Macrobiotidae) from Mississippi (USA) and Crete (Greece)

“…On the island of Crete, 28 species (from more than 150 samples) have been listed based on two sampling campaigns alone (Maucci and Durante Pasa 1982). Taking into consideration recent progress in tardigrade taxonomy and faunistic studies brought about by the integrative approach, it is more than likely that the region exhibits higher species diversity and additional sampling effort may reveal more species (Vuori et al 2020).…”