Articles
Early Access
Tardigrades of North America: more new records of occurrence for species of green tardigrades (Heterotardigrada: Echiniscoidea: Echiniscidae: Viridiscus)
Publisher's note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.
Published: 20 October 2025
77
Views
32
Downloads
Authors
Green pigmented tardigrades known as Viridiscus (Heterotardigrada: Echiniscoidea: Echiniscidae) are typically found in limnoterrestrial habitats, such as moss and lichens. However, the distribution of this genus in North America has been historically understudied and remains elusive to microbiologists, ecologists, and tardigrade taxonomists. In the last couple years, new state records of Viridiscus spp. in the United States of America (USA) have been documented from Alabama, Florida, Indiana, Tennessee, and Texas. Here we acknowledge the recent reports along with providing new additional USA records to give an update of Viridiscus spp. distribution. Two species of green tardigrades, Viridiscus perviridis and Viridiscus viridissimus, are reported from six locations in Illinois, Iowa, Minnesota, Mississippi, Missouri, and South Dakota. This is the first report of these species from these states and the farthest west that Viridiscus viridissimus has been found in continental North America. Additionally, we utilized polymerase chain reaction, DNA barcoding of the cytochrome oxidase I (COI) mitochondrial marker, a maximum likelihood phylogenetic analysis, and ASAP analysis to confirm the existence of Viridiscus viridissimus in Missouri.
Downloads
Download data is not yet available.
Citations
Altschul, S.F., Gish, W., Miller, W., Myers, E.W., & Lipman, D.J., 1990 – Basic local alignment search tool. Journal of Molecular Biology, 215(3): 403-410. DOI: https://doi.org/10.1016/S0022-2836(05)80360-2
Bartels, P.J., Coffey, D.C., Pineau, M., Kaczmarek, Ł., & Nelson, D.R., 2024 – An exploration of autofluorescence in tardigrades (phylum Tardigrada). Zoological Journal of the Linnean Society, 200(1): 200-217. DOI: https://doi.org/10.1093/zoolinnean/zlad045
Brandoli, S., Cesari, M., Massa, E., Vecchi, M., Rebecchi, L., & Guidetti, R., 2024 – Diverse eggs, diverse species? Production of two egg morphotypes in Paramacrobiotus bifrons, a new eutardigrade species within the areolatus group. The European Zoological Journal, 91(1): 274-297. DOI: https://doi.org/10.1080/24750263.2024.2317465
Brodo, I.M., 2016 – Keys to lichens of North America: revised and expanded. Yale University Press.
Brodo, I.M., Sharnoff, S.D., & Sharnoff, S., 2001 – Lichens of North America. New Haven (CT). Yale University Press. DOI: https://doi.org/10.29173/bluejay5827
Cotten, H., & Miller, W.R., 2022 – Tardigrades in Texas: Fifth Graders collaborate to add three new records to the state. Texas Journal of Science, 74(1): 1-19. DOI: https://doi.org/10.32011/txjsci_74_1_Article3
Crum, H., 1973 – Mosses of the Great Lakes forest. University of Michigan Press.
Crum, H., & Anderson, L.E., 1981 – Mosses of Eastern North America. Columbia University Press.
Degma, P., & Guidetti, R., 2007 – Notes to the current checklist of Tardigrada. Zootaxa, 1579: 41-53. DOI: https://doi.org/10.11646/zootaxa.1579.1.2
Degma, P., & Guidetti, R., 2024 – Actual checklist of Tardigrada species (2009-2024: 01-07-2024). Modena, Italy: Università di Modena e Reggio Emilia. Accessed 10-03-2024.
Fontoura, P., Pilato, G., & Lisi, O., 2011 – Tardigrada from Santo Antão Island (Archipelago of Cape Verde, West Africa) with the description of a new species. Zootaxa, 2838(1): 30-40. DOI: https://doi.org/10.11646/zootaxa.2838.1.2
Flora of North America Editorial Committee, eds. 1993 onwards – Flora of North America North of Mexico [Online]. 25+ vols. New York and Oxford. vol. 27, 2007; vol. 28, 2014. <http://beta.floranorthamerica.org> (retrieved in May 2024).
Gąsiorek, P., Morek, W., Stec, D., & Michalczyk, Ł., 2019 – Untangling the Echiniscus Gordian knot: paraphyly of the “arctomys group” (Heterotardigrada: Echiniscidae). Cladistics, 35(6): 633-653. DOI: https://doi.org/10.1111/cla.12377
Guidetti, R., & Bertolani, R., 2005 – Tardigrade taxonomy: an updated checklist of the taxa and a list of characters for their identification. Zootaxa, 845: 1-46. DOI: https://doi.org/10.11646/zootaxa.845.1.1
Kaczmarek, Ł., Michalczyk, Ł., & McInnes, S.J., 2014 – Annotated zoogeography of non-marine Tardigrada. Part I: Central America. Zootaxa, 3763(1): 1-063. DOI: https://doi.org/10.11646/zootaxa.3763.1.1
Kaczmarek, Ł., Michalczyk, Ł., & McInnes, S.J., 2015 – Annotated zoogeography of non-marine Tardigrada. Part II: South America. Zootaxa, 3923(1): 1-107. DOI: https://doi.org/10.11646/zootaxa.3923.1.1
Kaczmarek, Ł., Michalczyk, Ł., & McInnes, S.J., 2016 – Annotated zoogeography of non-marine Tardigrada. Part III: North America and Greenland. Zootaxa, 4203(1): 1-249. DOI: https://doi.org/10.11646/zootaxa.4203.1.1
Klips, R., 2022 – Common Mosses, Liverworts, and Lichens of Ohio: A Visual Guide. Ohio University Press.
Loeffelholz, J., Meese, E., Giovannini, I., Ullibarri, K., Momeni, S., Merfeld, N., Wessel, J., Guidetti, R., Rebecchi, L., & Boothby, T.C., 2024 – An evaluation of thermal tolerance in six tardigrade species in an active and dry state. Biology Open, 13(10): bio060485. DOI: https://doi.org/10.1242/bio.060485
Loeffelholz, J. D., Raynor, S., Sánchez-Moreno, S., Momeni, S., & Manzitto-Tripp, E., 2025 – Tardigrada and Nematoda associations with lichen and bryophyte habitats from Southwest Wisconsin state parks, universities, and private land. Biogeographia–The Journal of Integrative Biogeography, 40(1): a045. DOI: https://doi.org/10.21426/B6.40056
du Bois-Reymond Marcus, E., 1944 – Sobre Tardigrados Brasileiros. Comunicaciones Zoologicas del Museo de Historia Natural de Montevideo, 1(13): 1-19.
Massa, E., Rebecchi, L., & Guidetti, R., 2024 – Composition and structural organization of tardigrades feeding apparatus focusing on chitin and other autofluorescent molecules. Zoological Journal of the Linnean Society, 200(1): 186-199. DOI: https://doi.org/10.1093/zoolinnean/zlad028
Massa, E., & Vecchi, M., 2024 – Description of Macrobiotus kathyae sp. nov. (Parachela: Macrobiotidae) and first records of tardigrades from Indiana (USA). Zootaxa, 5471(3): 301-317. DOI: https://doi.org/10.11646/zootaxa.5471.3.1
McInnes, S.J., 1994 – Zoogeographic distribution of terrestrial/freshwater Tardigrades from Current Literature. Journal of Natural History, 28(2): 257-352. DOI: https://doi.org/10.1080/00222939400770131
McInnes, S.J., 2001 – Is it real?. Zoologischer Anzeiger-A Journal of Comparative Zoology, 240(3-4): 467-469. DOI: https://doi.org/10.1078/0044-5231-00055
McMullin, R.T., 2023 – Lichens: Macrolichens of Ontario and the Great Lakes Region of the United States. Firefly Books Limited.
Miller, W.R., & Perry, E.S., 2019 – Adjustments to the Annotated zoogeography of non-marine Tardigrada. Part III: North America and Greenland by Kaczmarek, Michalczyk & McInnes (Zootaxa 4203). Zootaxa, 4345, 99-114. DOI: https://doi.org/10.11646/zootaxa.4543.1.6
Miller, W.R., McCowan, P.J., Perry, E.S., Schulze, S.L., Shannon, R.K., & Henry, C.S., 2020 – Tardigrades of North America: New records of occurrence for three species of green tardigrades (Heterotardigrada, Echiniscoidea, Echiniscidae, Viridiscus). Transactions of the Kansas Academy of Science, 123(1-2): 235-241. DOI: https://doi.org/10.1660/062.123.0122
Momeni, S., Gąsiorek, P., Loeffelholz, J., Chtarbanova, S., Nelson, D.R., Fletcher, R.A., Michalczyk, Ł., & Pienaar, J., 2023 – Green armoured tardigrades (Echiniscidae: Viridiscus), including a new species from the Southern Nearctic, exemplify problems with tardigrade variability research. Scientific Reports, 13(1): 16329. DOI: https://doi.org/10.1038/s41598-023-40609-4
Morek, W., Ciosek, J.A., & Michalczyk, Ł., 2020 – Description of Milnesium pentapapillatum sp. nov., with an amendment of the diagnosis of the order Apochela and abolition of the class Apotardigrada (Tardigrada). Zoologischer Anzeiger, 288: 107-117. DOI: https://doi.org/10.1016/j.jcz.2020.07.002
Murray, J., 1910 – Tardigrada. British Antarctic Expedition 1907 - 1909. Reports on the Scientific Investigations, 1(5): 83-187.
Nelson, D.R., & Adkins, R.G., 2001 – Distribution of tardigrades within a moss cushion: do tardigrades migrate in response to changing moisture conditions?. Zoologischer Anzeiger-A Journal of Comparative Zoology, 240(3-4): 493-500. DOI: https://doi.org/10.1078/0044-5231-00058
Nelson, D.R., Fletcher, R. A., Guidetti, R., Roszkowska, M., Grobys, D., & Kaczmarek, Ł., 2020 – Two new species of Tardigrada from moss cushions (Grimmia sp.) in a xerothermic habitat in northeast Tennessee (USA, North America), with the first identification of males in the genus Viridiscus. PeerJ, 8: e10251. DOI: https://doi.org/10.7717/peerj.10251
Perry, E.S., Miller, W.R., & Lindsay, S., 2015 – Looking at tardigrades in a new light: using epifluorescence to interpret structure. Journal of Microscopy, 257(2): 117-122. DOI: https://doi.org/10.1111/jmi.12190
Péterfi, F., 1956 – Contributioni la cunoasterea Tardigradelor din RPR Studii si Cercetari de Biologia. Accademia RPR, Filiola Cluj, 7: 149-155.
Pilato, G., Fontoura, P., & Lisi, O., 2007 – Remarks on the Echiniscus viridis group with the description of a new species (Tardigrada, Echiniscidae). Journal of Limnology, 66 (suppl 1): 33-39. DOI: https://doi.org/10.4081/jlimnol.2007.s1.33
Pilato, G. Fontoura, P., & Lisi, O., 2008 – New description of Echiniscus viridis Murray, 1910 and remarks on the viridis group. New Zealand Journal of Zoology, 35: 85-92. DOI: https://doi.org/10.1080/03014220809510105
Ramazzotti, G., 1959 – Il gruppo dell' Echiniscus viridis con la nuova specie E. perviridis e Macrobiotus pustulatus altra nuova specie (Tardigrada). Atti della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale in Milano, 98(4): 303-309.
Ramazzotti, G. and Maucci, W., 1983 – II Phylum Tardigrada, (CW Beasley, English Translation). Memorie dell’Istitato idrobiologia, 41: 1-985.
Rocha, A., Camarda, D., Ostertag, B., Doma, I., Meier, F., & Lisi, O., 2023 – Actual State of Knowledge of the Limno-Terrestrial Tardigrade Fauna of the Republic of Argentina and New Genus Assignment for Viridiscus rufoviridis (du Bois-Reymond Marcus, 1944). Diversity, 15(2): 222. DOI: https://doi.org/10.3390/d15020222
Stec, D., Smolak, R., Kaczmarek, Ł., & Michalczyk, Ł., 2015 – An integrative description of Macrobiotus paulinae sp. nov. (Tardigrada: Eutardigrada: Macrobiotidae: hufelandi group) from Kenya. Zootaxa, 4052(5): 501-526. DOI: https://doi.org/10.11646/zootaxa.4052.5.1
Tamura, K., Stecher, G., & Kumar, S., 2021 – MEGA11: molecular evolutionary genetics analysis version 11. Molecular biology and evolution, 38(7), 3022-3027. DOI: https://doi.org/10.1093/molbev/msab120
How to Cite
Tardigrades of North America: more new records of occurrence for species of green tardigrades (Heterotardigrada: Echiniscoidea: Echiniscidae: Viridiscus). (2025). Natural History Sciences. https://doi.org/10.4081/nhs.2025.898
Copyright (c) 2025 the Author(s)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
PAGEPress has chosen to apply the Creative Commons Attribution NonCommercial 4.0 International License (CC BY-NC 4.0) to all manuscripts to be published.
