Integrative taxonomy supports the description of two new species of Macrobiotidae (Tardigrada, Eutardigrada) from Kristianstads Vattenrike Biosphere Reserve in Sweden

1 European Journal of Taxonomy 1030: 1–52 https://doi.org/10.5852/ejt.2025.1030.3135 europeanjournaloftaxonomy.eu ISSN 2118-9773 2025 · Hulterström J. et al. This work is licensed under a Creative Commons Attribution License (CC BY 4.0) Received: 21 March 2025 • Accepted: 26 August 2025 • Published: 8 December 2025 Topic editor: Magalie Castelin • Section editor: Daniel Stec • Desk editor: Pepe Fernández Monograph urn:lsid:zoobank.org:pub:60D8486F-0A30-423A-832B-3B5BF58C20ED Integrative taxonomy supports the description of two new species of Macrobiotidae (Tardigrada, Eutardigrada) from Kristianstads Vattenrike Biosphere Reserve in Sweden Jens HULTERSTRÖM 1 , Roberto GUIDETTI 2 , K. Ingemar JÖNSSON 3 & Sarah ATHERTON 4,* 1,4 Department of Zoology, Swedish Museum of Natural History, Box 50007, 104 05 Stockholm, Sweden. 2 Department of Life Sciences, University of Modena and Reggio Emilia, 41124 Modena, Italy. 3 Department of Environmental Science, Kristianstad University, SE-291 88 Kristianstad, Sweden. * Corresponding author: [email protected] 1 Email: [email protected] 2 Email: [email protected] 3 Email: [email protected] Abstract. Kristianstads Vattenrike Biosphere Reserve (KVBR) in the south of Sweden is a known hotspot for tardigrades, with almost a third of the country’s tardigrades species reported from this location alone. Herein, the tardigrade diversity of the KVBR is further investigated. New records for the country are reported and two new species, Macrobiotus vattenrikense sp. nov. and Paramacrobiotus marchelmoni sp. nov., described using an integrative taxonomic approach. An updated multi-locus phylogeny to the family Macrobiotidae is provided with the inclusion of the newly described species. Keywords. Biodiversity, Macrobiotus, morphology, Paramacrobiotus, phylogeny. Hulterström J., Guidetti R., Jönsson K.I. & Atherton S. 2025. Integrative taxonomy supports the description of two new species of Macrobiotidae (Tardigrada, Eutardigrada) from Kristianstads Vattenrike Biosphere Reserve in Sweden. European Journal of Taxonomy 1030: 1–52. https://doi.org/10.5852/ejt.2025.1030.3135 Introduction Tardigrada Doyère, 1840 is a phylum of small metazoans present within a broad range of substrates including: marine sediments from the littoral zone to abyssal depths (Bussau 1992), glacial cryoconite holes (Zawierucha et al. 2014), rock pools (Vecchi et al. 2022b; Troell & Jönsson 2023), limnic habitats, leaf-litter, soil, liverwort, lichen, and moss, from which they are most commonly studied (Nelson et al. 2018). The diversity and distributions of tardigrade fauna have been increasingly investigated over the last few decades, with the number of recognized species increasing significantly from ~530 species in 1983 (Ramazzotti & Maucci 1983) to more than 1500 species today (Degma & Guidetti 2024). European Journal of Taxonomy 1030: 1–52 (2025) 2 Nevertheless, modelled estimations conclude that the true diversity of the phylum is significantly higher (Bartels et al. 2016). In total, 118 species of tardigrade (plus five additional species with incomplete or uncertain “cf.” or “aff.” designations) are known from Sweden (Guidetti et al. 2025, and references therein). Tardigrades have been recorded from almost every major Swedish province, including the Baltic Islands Öland and Gotland, with the vast majority reported from the provinces Uppland, Lappland, and, more recently, Skåne (Massa et al. 2021; Atherton et al. 2025; Guidetti et al. 2025). Located within the southernmost province of Skåne, Kristianstads Vattenrike Biosphere Reserve (KVBR) is a UNESCO designated area that incorporates urban environments and rural areas with natural habitats such as wetlands, forest, lakes, and rivers (Olsson et al. 2007). This ~1050 km 2 area is highly significant for tardigrade biodiversity since seven of the 28 (25%) Swedish type localities and 36 (30%) Swedish species are reported from KVBR (Massa et al. 2021; Atherton et al. 2025; Guidetti et al. 2025). The limnoterrestrial eutardigrade family Macrobiotidae Thulin, 1928 consists of up to 15 genera. The most species-rich and widespread of these is Macrobiotus Schultze, 1834, whose exact composition and subsequent monophyly has recently been the subject of much discussion (Massa et al. 2021; Stec et al. 2021a; Vecchi et al. 2022c; Bertolani et al. 2023; Stec 2024; Vincenzi et al. 2024). While all modern phylogenetic analyses do consistently recover three lineages (denoted as clade “A”, “B” and “C” by Stec et al. 2021a) for the taxon, no morphological definitions have been proposed that will either separate the three clades or encompass all the species morphologies. A second genus of Macrobiotidae, Paramacrobiotus Guidetti, Schill, Bertolani, Dandekar & Wolf, 2009, was erected based on integrative taxonomy and is distinguished by 1) the presence of three macroplacoids in the pharyngal bulb, 2) a microplacoid that, if present, is situated farther than its own length from the macroplacoid row and 3) possessing eggs with an areolated chorion. Two subgenera were proposed for the genus (Kaczmarek et al. 2017, amended by Marley et al. 2018), based on presence or absence of microplacoid, but were ultimately rejected after phylogenetic analyses determined they were non-monophyletic. They are instead currently accepted as the informal richtersi (with microplacoid) and areolatus (without microplacoid) morphogroups (Guidetti et al. 2019a; Stec et al. 2020c). Paramacrobiotus comprises 47 nominal species (Degma & Guidetti 2024), including two nomina dubia and two species which are based solely on genetic data without morphological distinction (Schill et al. 2010; Guidetti et al. 2019a; Stec et al. 2020c). Herein, the tardigrade composition of two samples of moss collected from KVBR is documented, including some new records for the country. Two species, Macrobiotus vattenrikense sp. nov. and Paramacrobiotus marchelmoni sp. nov., are introduced for the first time based on a combination of morphological and molecular taxonomy. These descriptions form part of a larger ArtDatabanken sponsored biodiversity project that aims to catalog macrobiotid tardigrades within Sweden. Material and methods Substrate collection and animal extraction Moss was collected from an open grassland pasture within KVBR in Skåne, Sweden (Sånnarna; 55°55′41.6″ N, 14°15′11.1″ E) on 21 March 2022 (Supp. file 1). The moss was growing on calcareousrich sand with full sunlight exposure at an altitude of ~8 m above sea level. The sample was transported to the Swedish Museum of Natural History in Stockholm, where it was air dried and stored until extraction. During extraction, the dry sample was submersed in tap water for 0.5–3 h, then the contents were stirred vigorously and the top water poured through 250 µm and 40 µm mesh sieves. The sieves were back-washed with tap water into a petri-dish, and individual animals and eggs detected under a HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 3 Nikon SMZ 1500 stereo microscope. Water was poured back into the initial cup containing the substrate and the process repeated after ~24 h for an increased yield of individuals per sample. Individual animals and eggs were transferred in water to a microscope glass slide under a cover slip and identified to the lowest possible taxonomic level with a Nikon Eclipse 80i compound microscope equipped with Differential Interference Contrast (DIC). Light micrographs were taken of each using a Canon EOS 5D Mark III digital camera. Animals and eggs were subsequently fixed on a permanent slide in Hoyer’s fluid, prepared for Scanning Electron Microscopy (SEM), or saved in 95% ethanol for later DNA-analysis. Morphometric measurements were taken from fixed animals on slides under 100 × immersion oil objective using an ocular micrometer and from photographs of the same using GIMP ver. 2.10.36. Critical point drying prior to SEM analysis was achieved by boiling the specimens in pure ethanol following the protocol in Guidetti et al. (2019b). Dry specimens were moved using an eyebrow hair mounted on a glass pipette onto double-sided carbon tape on a SEM stub. A thin layer of gold was applied using a sputter coater before viewing with FEI Quanta FEG 650 SEM at the Swedish Museum of Natural History, Stockholm. All type material is stored in the Swedish Museum of Natural History in Stockholm, Sweden (SMNH) and in the Bertolani Collection of the University of Modena and Reggio Emilia, Italy (MUSN). DNA extraction, amplification, and sequencing protocol DNA from whole individual adults or eggs was extracted using a Qiagen DNeasy kit following the manufacturer’s instructions. PCR amplification was performed using 0.2 ml PuReTaq Ready-to-go PCR Beads (GE Healthcare) with 5 pmol each forward and reverse primers and 3 µl DNA. Four gene regions were selected for amplification: the ~650 bp “Folmer region” (Folmer et al. 1994) of the mitochondrial cytochrome oxidase subunit 1 (COI), the ~450 bp nuclear ribosomal internal transcribed spacer (ITS2), a ~900 bp fragment of the ribosomal large subunit (28S), and the full ~1800 bp ribosomal small subunit (18S), assembled from three overlapping fragments. For Paramacrobiotus marchelmoni sp. nov. the full 18S sequencing was unsuccessful, and a ~1300 bp fragment was amplified instead. Supp. file 2: sheet 1, lists all primer pairs and PCR protocols. PCR-product was examined on 1% agarose gel with gel-green and purified using ExoSAP-IT enzymes (Exonuclease and Shrimp Alkaline Phosphotase; GE Healthcare) and DNA sequencing was conducted by Macrogen Europe (Netherlands). Sequences were assembled in Aliview ver. 1.28 (Larsson 2014) and checked for ambiguous base calls using FinchTV ver. 1.4.0 (Geospiza inc.). The mitochondrial COI gene was aligned as translated amino acids according to the standard invertebrate mitochondrial code to check for stop codons and pseudogenes. Phylogenetic and species delimitation analyses Newly generated sequences were combined with sequences of Macrobiotidae downloaded from GenBank as well as Richtersius coronifer (Richters, 1903) and Diaforobiotus islandicus (Richters, 1904), which were selected as outgroups. Appendix 1 lists the GenBank accession numbers for all sequences used in this study. Sequences were aligned in Aliview ver. 1.28 (Larsson 2014) using the incorporated MUSCLE algorithm (Edgar 2004) for multiple alignment. Concatenation of datasets from the genes COI, 18S, 28S, and ITS2 was done with Concatenator ver. 0.2.1 (Vences et al. 2022). The ITS2 dataset was cleaned of uninformative sites and ambiguously aligned blocks with Gblocks ver. 0.91.1 using the default settings and allowing for gap positions (Talavera & Castresana 2007). European Journal of Taxonomy 1030: 1–52 (2025) 4 Maximum likelihood (ML) phylogenetic analysis was conducted using the IQtree-web server (Trifinopoulos et al. 2016) with 1000 replicates of ultrafast bootstrap trees to test topological support. Modelfinder (Kalyaanamoorthy et al. 2017) incorporated in IQ-tree found the best fitting substitution model under the Bayesian Information Criterion for each dataset, and selected models are given in Supp. file 2: sheet 2. Species inference was tested through multi-rate Poisson tree processes (mPTP) using default parameters under ML and Markov chain Monte Carlo (https://mptp.h-its.org; Kapli et al. 2017) using input trees generated from ML analyses of COI. Pairwise uncorrected genetic distances (p-distances) within and between species of Macrobiotus “clade B” and Paramacrobiotus were calculated in MEGA (Kumar et al. 2018) for the COI and the unfiltered ITS2 sequences, with each species defined following the results of the mPTP analysis. Morphological and morphometric analysis Animals and eggs fixed in Hoyer’s fluid (Morek et al. 2016) were morphologically analysed and measured under 100 × oil immersion magnification. Morphometric measurements were processed in the Parachela ver. 1.8 template available from the Tardigrada Register, www.tardigrada.net/register (Michalczyk & Kaczmarek 2013). The measured data was supplemented with the pt index (Pilato 1981). Measurements of claws, eggs, and buccal apparatus were taken following Michalczyk & Kaczmarek (2017), and only if they were in the appropriate position. Claws were measured either in frontal or lateral view. Body length was measured excluding the hind legs, and the buccal tube from the posterior end of the oral cavity to the posterior end of the buccal tube within the pharynx. Inner and outer buccal tube width was measured at the stylet insertion point. The diameter of oval eggs was measured at the widest point. Egg processes were counted around the circumference with the widest margin of the egg in focus in accordance with Kaczmarek & Michalczyk (2017). Egg process height was measured in lateral view on the circumference. Figures were processed with GIMP ver. 2.10.36 (https://www.gimp.org/downloads/) and deep focus images were generated form a stack of 2–6 images using Helicon Focus ver. 8.2.2 (https://www.heliconsoft.com/software-downloads/). Results Faunistics A total of eight morphospecies were isolated from the sample: Hypsibius pallidus Thulin, 1911; Macrobiotus vattenrikense sp. nov.; Macrobiotus aff. nelsonae Guidetti, 1998; Milnesium tardigradum Doyère, 1840; Paramacrobiotus fairbanksi Schill, Förster, Dandekar & Wolf, 2010; Paramacrobiotus marchelmoni sp. nov.; Ursulinius lunulatus (Iharos, 1966); and Tenuibiotus sp. The identification of P. fairbanksi was confirmed by DNA analyses (Figs 1, 3; Supp. files 3, 4, 5, 6) and represents a new record for Sweden. Macrobiotus. aff. nelsonae and Tenuibiotus sp. are likely new to science. Paramacrobiotus marchelmoni sp. nov. and P. fairbanksi were initially distinguished from each other based on the shape of the microplacoid, which is comma-shaped in P. fairbanksi (Supp. file 7B) and heart-shaped with ventrolateral wings in P. marchelmoni (Fig. 9B). Paramacrobiotus fairbanksi has been meticulously studied numerous times from populations found over a wide geographic range: Antarctica (Kaczmarek et al. 2020b), Denmark (Gąsiorek et al. 2024), Finland (Vecchi et al. 2024b), Italy (Guidetti et al. 2019a), Poland (Stec et al. 2020c), Spain (Guil & Giribet 2012; Guidetti et al. 2019a), and USA (Alaska; Schill et al. 2010), and has never been reported with anything other than a comma-shaped microplacoid, supporting the character’s validity as a way to distinguish between the two species. The species distinction was subsequently confirmed via differences in egg morphology (number of areolae surrounding each, widths of the processes bases and shape of the process apexes; see HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 5 differential diagnosis for P. marchelmoni and compare Figs 9, 11 with Supp. file 7) and via molecular analysis (Fig. 3). The specimens of Macrobiotus aff. nelsonae and M. vattenrikense sp. nov. were initially distinguished from each other based on the clearly smaller lunulae and large, elliptical pores of the former (Supp. file 8) compared to the larger lunulae and small, rounded cuticular pores of the latter (Figs 4–5). Their separation was subsequently confirmed by their different egg morphologies, with M. aff. nelsonae determined to be of the nelsonae-group based on the presence of oval areolae (Kaczmarek et al. 2023). Additionally, the eggs of M. aff. nelsonae had conical processes with a smooth and rounded cap on the apex that do not match the eggs of any described taxa in the nelsonae-group (Kaczmarek et al. 2023), which suggests the species is likely unknown to science. Unfortunately, all attempts to attain DNA sequences for the species were unsuccessful. The connection between the egg and the adult morphology of M. aff. nelsonae was facilitated by a hatchling. Only a single adult specimen and no eggs were found for Tenuibiotus sp. The specimen matched the morphological characterization of Tenuibiotus Pilato & Lisi, 2011 as defined by Stec & Morek (2022): tenuis-type claws (Pilato & Lisi 2011), a non-porous cuticle, and a pharynx with rows of two macroplacoids – the first with a deep constriction – and single microplacoid (Supp. file 9). DNA sequences attained from the specimen grouped within the Tenuibiotus clade but were distinct from the available sequences of the other species of the genus (Fig. 1). This is the first record of the genus in Sweden. Phylogenetic analyses Results from individual gene and concatenated datasets were largely consistent with each other (Figs 1–3; Supp. files 3, 4, 5, 6) and with previous reports (Guidetti et al. 2009, 2019a; Stec et al. 2020d, 2021a; Kayastha et al. 2023b; Vincenzi et al. 2024). The COI and ITS2 gene trees (Supp. file 3, Supp. file 5) displayed lower support for deeper nodes, while the 18S and 28S gene trees (Supp. file 4, Supp. file 6) failed to separate several closely related species, but such results are unsurprising given the evolutionary rates of the loci (Klopfstein et al. 2017). Figure 1 depicts the results of the family level analyses of the four gene concatenated dataset. Sisubiotus Stec, Vecchi, Calhim & Michalczyk, 2021, Mesobiotus Vecchi, Cesari, Bertolani, Jönsson, Rebecchi & Guidetti, 2016 and Macrobiotus + Xerobiotus Bertolani & Biserov, 1996 grouped together with moderate support. Macrobiotus formed three well-supported clades that correspond to clade “A”, “B” and “C” of Stec et al. (2021a, 2022), Vecchi et al. (2022c), and Vincenzi et al. (2024), with Xerobiotus nested within Macrobiotus “clade B”. Macrobiotus vattenrikense sp. nov. was recovered in “clade B” as sister to Macrobiotus mileri Stec, 2024. Minibiotus Schuster, 1980 (in Schuster et al. 1980) comprised two paraphyletic lineages that grouped with a supported Tenuibiotus and Paramacrobitous clade. Paramacrobiotus was split into two evolutionary lineages corresponding to the arelatus-group and the richtersi-group + P. lachowskae Stec, Roszkowska, Kaczmarek & Michalczyk, 2018. Paramacrobiotus marchelmoni sp. nov. was recovered within the richtersi-group clade as sister to a clade consisting of Paramacrobiotus gadabouti Kayastha, Stec, Mioduchowska & Kaczmarek, 2023 (in Kayastha et al. 2023b) and an unidentified Paramacrobiotus sp. from New Zealand (Paramacrobiotus sp. “strain NZ.001”). The new species clustered as a single species with two sequences from GenBank: (I) “Macrobiotus pallarii tar407” collected from outside Madrid (Guil & Giribet 2012) and (II) Paramacrobiotus sp. “strain HU.012” collected in Budapest, Hungary (Stec et al. 2020c). European Journal of Taxonomy 1030: 1–52 (2025) 6 Fig. 1. Concatenated 18S, 28S, COI and ITS2 ML tree. Ultrafast bootstrap support is given at the nodes and species with newly generated genetic data are highlighted in red. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 7 Species inference with multi-rate Poisson tree processes (mPTP) The mPTP analyses recovered 14 species in Macrobiotus “clade B” (Fig. 2) and 26 species in Paramacrobiotus (Fig. 3), with all nominal species as separate species. Additionally, Macrobiotus fontourai Bertolani, Cesari, Giovannini Rebecchi, Guidetti, Kaczmarek & Pilato, 2022 and M. cf. muralis Bertolani, Cesari, Giovannini Rebecchi, Guidetti, Kaczmarek & Pilato, 2022 were recovered as a single species, consistent with the ASAP-analysis in Bertolani et al. (2023). All specimens of Macrobiotus vattenrikense sp. nov. were delineated as single species, and all specimens of Paramacrobiotus Fig. 2. Concatenated 18S and COI ML tree of Macrobiotus Schultze, 1834 “clade B” with results from the mPTP analysis. Ultrafast bootstrap support is given at the nodes, and specimens with newly generated genetic data are highlighted in red. Bars are colored consistent with the results of the mPTP analysis, where the transitions from blue to red represent speciation. European Journal of Taxonomy 1030: 1–52 (2025) 8 Fig. 3. Concatenated 18S and COI ML tree of Paramacrobiotus Guidetti, Schill, Bertolani, Dandekar & Wolf, 2009 with results from the mPTP analysis. Ultrafast bootstrap support is given at the nodes, and specimens with newly generated genetic data are highlighted in red. Bars are colored consistent with the results of the mPTP analysis, where the transitions from blue to red represent speciation. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 9 marchelmoni sp. nov. + “Macrobiotus pallarii tar407” + Paramacrobiotus sp. “strain HU.012” were delineated as a single species. Pairwise genetic distances within and between species of Macrobiotus “clade B” and Paramacrobiotus are given in Supp. file 2: sheets 3–6, with each species defined following the results of the mPTP analyses (Figs 2–3). For Macrobiotus “clade B”, intraspecific distances were 0.0–4.2% for COI and 0.0–1.3% for ITS2 and interspecific distance were 14.0–24.9% for COI and 0.8–11.6% for ITS2. For Paramacrobiotus, intraspecific distance were 0.0–5.3% for COI and 0.0–1.6% for ITS2 and interspecific distance were 10.5–27.6% for COI and 1.4–32.7% for ITS2. For P. fairbanksi, specimens from Sweden differed from the specimens from other countries by 0.0–0.3% for COI and 0.0–0.9% for ITS2. Specimens of P. marchelmoni sp. nov. from Sweden differed from the specimen from Hungary (“HU.012”) by 0.6–0.8% for COI and 0.9–1.5% for ITS2 and the specimen from Spain (“tar407”) by 0.0–0.2% for COI (no ITS2 sequence is available for “tar407”). Taxonomy Class Eutardigrada Richters, 1926 Order Parachela Schuster, Nelson, Grigarick & Christenberry, 1980 Family Macrobiotidae Thulin, 1928 Genus Macrobiotus Schultze, 1834 Macrobiotus vattenrikense sp. nov. urn:lsid:zoobank.org:act:0F5EEA46-2A3D-4D72-B776-CB812C013993 Figs 4–8 Diagnosis Macrobiotus with three bands of teeth in oral cavity armature (OCA): first and second of granules, and third of a transverse crest non-uniform in shape on the dorsal and ventral side, with a dorsal side with one elongated tooth and ventral side with two lateral and two medial teeth. Two macroplacoids, the first with a slight central constriction, the second with a pre-terminal constriction, and a comma-shaped microplacoid. Claws of similar size on all legs, with large, smooth lunulae on legs I–III and serrated on legs IV. Eggs of hufelandi-type with inverse goblet-shaped processes with indented process disks without granulation. Egg chorion with a wrinkled or granulated surface, appears solid in LM but with a ring of small pores around each process visible in SEM. Etymology The new species is named after the area of the type locality within Kristianstads Vattenrike Biosphere Reserve, in dedication to its high tardigrade biodiversity. Material examined A total of 16 animals and 7 eggs observed, including: 10 animals and 6 eggs mounted in Hoyer’s fluid, 2 animals and 1 egg fixed for SEM, and 4 animals used for DNA extraction. Type material Holotype SWEDEN • Skåne, Sånnarna; 55°55′41.6″ N, 14°15′11.1″ E; 8 m a.s.l.; 22 Mar. 2021; S. Atherton, R. Guidetti and K.I. Jönsson leg.; moss on calcareous-rich sand and rock; SMNH, slide SMNHType-10010. European Journal of Taxonomy 1030: 1–52 (2025) 16 Fig. 8. Macrobiotus vattenrikense sp. nov., SEM photographs of egg (SMNH, SMNH-Type-10016). A. Whole egg. B–C. Egg processes and chorion. White arrowheads indicate examples of the very small pores that surround the base of each process. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 17 the egg may be easily overlooked with light microscopy/clearly visible only with SEM, and so species with similar egg morphologies that have not been observed with SEM are included): Macrobiotus halophilus Fontoura, Rubal & Veiga, 2017 – the animals of M. vattenrikense sp. nov. differ from animals of M. halophilus in the wider buccal tube (external width pt 16.7–20.9 compared with pt 13.2–16.5 in M. halophilus); the lack of a deep constriction in the first macroplacoid; the paired ventromedial teeth and single fused dorsal tooth in the third band of the OCA (compared with an undivided ventromedial tooth and three distinct dorsal teeth in M. halophilus); the shorter claws (posterior claw IV pt 23.8–33.3 compared to 33.4–42.0 in M. halophilus); and the lack of male gibbosities. The eggs of M. vattenrikense are differentiated by the larger processes (height 6.0–7.3 µm compared to 3.9–5.9 µm in M. halophilus). In addition, the very small pores that are present surrounding the egg processes of M. vattenrikense have not been documented for M. halophilus, although eggs of the latter species have not been observed with SEM. Macrobiotus marlenae Kaczmarek & Michalczyk, 2004 – the animals of M. vattenrikense sp. nov. differ from the animals of M. marlenae by the granulation present on all legs (compared to granulation only on legs IV in M. marlenae); the shallower constriction of the first macroplacoid; the subterminal constriction in the second macroplacoid; and the claws with larger lunules in M. vattenrikense The eggs of M. vattenrikense have more numerous (23–25 on the circumference compared to 16 in M. marlenae) processes that are shorter (6.0–7.3 µm compared to 8.4–8.8 µm in M. marlenae), more closely spaced (inter-process distance 2.9–4.2 µm compared with 4.5–6.5 µm in M. marlenae), and with much smaller terminal disks (diameter 3.2–4.8 µm compared to 9.5–11.4 µm in M. marlenae). In addition, the very small pores that are present surrounding the egg processes of M. vattenrikense have not been documented for M. marlenae, although eggs of the latter species have not been observed with SEM. Macrobiotus ovovittatus Stec, 2024 – the animals of M. vattenrikense sp. nov. are smaller than animals of M. ovovittatus (335–530 µm compared to 570–879 µm in M. ovovittatus) and have a shorter first macroplacoids (pt 21.4–27.8 compared to pt 28.4–34.4 in M. ovovittatus) with shallower median incision. The new species is further distinguished by the paired ventromedial teeth and single fused dorsal tooth in the third band of OCA (compared with an undivided ventromedial tooth and three distinct dorsal teeth in M. ovovittatus), and the lack of cuticular bars below the claws of the first three pairs of legs (bars present in M. ovovittatus). The eggs of M. vattenrikense are smaller than those of M. ovovittatus (diameter without the processes 62.3–78.2 µm compared to 100.6–129.8 µm in M. ovovittatus) with fewer processes on the circumference (23–25 compared to 28–34 in M. ovovittatus), and smaller processes (height 6.0–7.3 µm Table 2. Morphometric data for the eggs of the new species, including the number of measurements for each character, the range of the measurements, the mean and standard deviation. M. vattenrikense sp. nov. P. marchelmoni sp. nov. n Range (µm) Mean ± SD (µm) n Range (µm) Mean ± S D (µm) Egg bare diameter 6 62.3–78.2 74.0 ± 6.2 13 67.0–92.4 77.2 ± 7.5 Egg full diameter 6 74.0–90.5 86.4 ± 6.4 13 92.5–115.0 102.2 ± 8.6 Process height 18 6.0–7.3 6.7 ± 0.4 40 10.0–16.5 13.0 ± 1.6 Process base width 18 6.0–7.2 6.8 ± 0.4 39 21.3–30.0 24.1 ± 2.4 Process width/height 18 0.86–1.17 1.01 ± 0.10 39 1.44–2.25 1.86 ± 0.23 Terminal disk width 18 3.2–4.8 4.0 ± 0.5 – – – Interprocess distance 18 2.9–4.2 3.5 ± 0.4 30 4.0–10.0 5.8 ± 1.1 Processes on circumference 6 23–25 24.2 ± 1.0 14 10–12 11.1 ± 0.9 European Journal of Taxonomy 1030: 1–52 (2025) 18 compared to 9.5–13.5 µm in M. ovovittatus; diameter at the base 6.0–7.2 µm compared to 9.4–13.6 µm in M. ovovittatus) with smaller (diameter 3.2–4.8 µm compared to 6.1–8.7 µm in M. ovovittatus), solid terminal disks (covered by multiple light-refracting dots in M. ovovittatus). Macrobiotus persimilis Binda & Pilato, 1972 (following the redescription of Bertolani et al. 2023) – the animals of M. vattenrikense sp. nov. differ from animals of M. persimilis in the lack of a deep constriction in the first macroplacoid; the shorter macroplacoids (first/second macroplacoid pt 21.4–27.8/16.7–20.9 compared to pt 32.0–33.8/22.8–24.2 in M. persimilis) and macroplacoid row (pt 37.1–52.8 compared to pt 54.7–57.2 in M. persimilis); the longer microplacoids (pt 8.6–11.6 compared to pt 7.7–8.0 in M. persimilis); the paired ventromedial teeth and single fused dorsal tooth in the third band of the OCA (compared with an undivided ventromedial tooth and three distinct dorsal teeth in M. persimilis); and the shorter claws (external claw III/IV pt 23.3–33.3/25.6–30.6 compared to 35.9–38.3/35.9–37.9 in M. persimilis). The eggs of M. vattenrikense are differentiated by the larger processes (height 6.0–7.3 µm compared to 3.7–5.3 µm in M. persimilis; diameter at the base 6.0–7.2 µm compared to 3.6–5.1 µm in M. persimilis). In addition, the very small pores that are present surrounding the egg processes of M. vattenrikense have not been documented for M. persimilis, although eggs of the latter species have not been observed with SEM. Macrobiotus polonicus Pilato, Kaczmarek, Michalczyk & Lisi, 2003 – the animals of M. vattenrikense sp. nov. differ from the animals of M. polonicus by the presence of granulation lateral to the claws on legs I–III (absent in M. polonicus); the absence of lateral gibbosites on the hind legs (present in M. polonicus); the absence of sclerotized areas near the lunulae of legs I–III (present in M. polonicus). The eggs of M. vattenrikense differ by the smaller diameter of the process terminal disks (3.2–4.8 µm compared with 4.9–6.3 µm in M. polonicus) and by the minute pores surrounding each process (lack of egg pores for M. polonicus confirmed with SEM). Macrobiotus trunovae Biserov, Pilato & Lisi, 2011 – the animals of M. vattenrikense sp. nov. differ from animals of M. trunovae by the paired ventromedial teeth and single fused dorsal tooth in the third band of the OCA (compared with an undivided ventromedial tooth and three distinct dorsal teeth in M. trunovae); the more anteriorly inserted stylet supports (pt 75.0–81.0 compared to 81.7–82.4 in M. trunovae); the smaller first macroplacoid (pt 21.4–27.8 compared to 28.3–31.4 in M. trunovae) with a much narrower constriction; and the similar sizes of the claws on all legs (compared to distinctly smaller claws on legs I–III than on legs IV in M. trunovae). The eggs of M. vattenrikense are smaller (diameter without processes 62.3–78.2 µm compared to 134.3 µm in M. trunovae) with fewer (23–25 on the egg circumference compared to 32 in M. trunovae) and smaller (length 6.0–7.3 µm compared to up to 10.9 µm in M. trunovae; diameter at the base 6.0–7.2 µm compared to 9.1–9.9 µm in M. trunovae) processes. In addition, the very small pores that are present surrounding the egg processes of M. vattenrikense have not been documented for M. trunovae, although eggs of the latter species have not been observed with SEM. Genus Paramacrobiotus Guidetti, Schill, Bertolani, Dandekar & Wolf, 2009 Paramacrobiotus marchelmoni sp. nov. urn:lsid:zoobank.org:act:C91427F4-F50C-4A1F-A475-825777258AE5 Figs 9–11 Diagnosis Paramacrobiotus without eyespots. Cuticle with fine dorsal granulation visible only in SEM, and medium-coarse granulation surrounding the claws of the legs I–IV visible with DIC and SEM. OCA with three bands of teeth: first composed of numerous small granules, second of a single row of vertical HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 19 ridges, and third of three ventral and three dorsal transverse crests. Three rod-like macroplacoids and a distant microplacoid present. Claws of hufelandi-type with smooth lunulae. Freely laid eggs with sculptured areolae of richtersi-type; 10–12 reticulated processes around the circumference, conical with a mostly smooth apex. Etymology The species is proudly in dedication to Marc “Marchelmon” Hulterström, brother of the first author. Material examined A total of 38 animals and 24 eggs observed, including: 16 animals and 15 eggs mounted in Hoyer’s fluid, 10 animals and 5 eggs fixed for SEM, and 11 animals and 4 eggs used for DNA analysis. Type material Holotype SWEDEN • Skåne, Sånnarna; 55°55′41.6″ N, 14°15′11.1″ E; 8 m a.s.l.; 22 Mar. 2021; S. Atherton, R. Guidetti and K.I. Jönsson leg.; moss on calcareous-rich sand and rock; SMNH, slide SMNHType-10017. Paratypes SWEDEN · 23 specs, 15 eggs; same collection data as for holotype; SMNH, slides SMNH-Type-10018 to SMNH-Type-10029, SEM stub SMNH-Type-10030 • 3 specs, 5 eggs; same collection data as for holotype; GenBank nos: PX093656 to PX093658 (COI), PX093645, PX093646 (ITS), PX093665 (18S), PX093651 (28S); MUSN, slides 22-030, 22-037 and 22-103. Description Morphometric measurements and statistics given in Tables 1 and 2 (raw morphometric data is given in Supp. file 11). Paramacrobiotus with body length 238–710 µm (Fig. 9A). Eyespots absent. Cuticle transparent in live animals and after fixation in Hoyer’s fluid. Dorsal body cuticle with even and very fine granulation, visible only with SEM (Fig. 10A–B). A patch of larger granulation lateral to the claws on legs I–III and coarse granulation fully surrounding the claws on legs IV visible with DIC and SEM (Figs 9F, 10B–D). Cuticular pores, gibbosities, and papillae absent. Mouth antero-ventral; ten peribuccal lamellae present. Buccal apparatus with a rigid tube of Macrobiotustype (Pilato & Binda 2010) with ventral lamina. OCA comprising three bands of teeth (Fig. 9C–D). First band a field of small granular teeth situated closely behind the peribuccal lamellae. Second band one row of vertical ridges, uniform in shape on both ventral and dorsal side. Third band situated close to the second, with three ventral and three dorsal teeth, with the lateral teeth wider (larger along the left/right axis) and shorter (smaller along the anterior/posterior axis) than the median tooth for each side. Ventral teeth thinner (smaller along the left/right axis) than dorsal teeth (Fig. 9C). Latero-dorsal teeth triangular, narrowing away from the median tooth (Fig. 9D). No additional granular teeth observed between the second and third band of OCA. Globular pharyngeal bulb with triangular pharyngeal apophyses, three rod-shaped macroplacoids with length sequence 2 < 1 < 3, and a microplacoid (Fig. 9B). First macroplacoid drop-like. Second macroplacoid oval. Third macroplacoid with a subterminal constriction, ending in posterior bulbs. Microplacoid heart-shaped, with antero-lateral wings, and situated distant from the third macroplacoid, further than its length. Double-claws of hufelandi-type (Bertolani & Pilato 1988). Main claw branches with evident accessory points. Smooth lunulae on all claws (Figs 9E, 10B–D). Paired muscle attachments below claw present. Cuticular bars absent. European Journal of Taxonomy 1030: 1–52 (2025) 20 Fig. 9. Paramacrobiotus marchelmoni sp. nov. A. DIC photograph of paratype in water (SMNH, SMNH-Type-10018); whole body. B. DIC photograph of holotype in Hoyer’s fluid (SMNH, SMNHType-10017); pharynx and placoids. C. DIC photograph of holotype in Hoyer’s fluid (SMNH, SMNH-Type-10017); dorsal OCA. D. DIC photograph of holotype in Hoyer’s fluid (SMNH, SMNHType-10017); ventral OCA. E. DIC photograph of paratype in Hoyer’s fluid (MUSN, 22-103); claws of leg I. F. DIC photograph of paratype in water (SMNH, SMNH-Type-10019); claws of leg IV. White indented arrowhead indicates constriction of the third macroplacoid; black arrowhead indicates first row of OCA; black full arrows indicate second row of OCA; black indented arrowheads indicate third row of OCA; asterisk indicates leg granulation. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 21 Gonochoristic. Males with sperm filled testis observed, as well as females with eggs. Ornamented eggs laid freely, richtersi-type (Kaczmarek et al. 2017; Fig. 11A–B), diameter without processes 67.0–92.4 µm. Processes conical, short (10–16.5 µm) and wide (21.3–30.0 µm), with a smooth rounded apex (Fig. 11A–E). 10–12 processes on the circumference (Fig. 11B). Processes smooth in SEM (Fig. 11A) but labyrinthine layer visible in DIC as a reticular pattern of small, evenly distributed meshes (Fig. 11C). Processes surrounded by a single ring of 12 areolae (Fig. 11A, G). Areolae with sculpturing comprising dotlike indentations, faintly visible fixed in Hoyer’s with DIC and clearly visible with SEM (Fig. 11F). DNA sequences Sequences for P. marchelmoni sp. nov. were attained for all four molecular markers using 11 animals and four eggs. 18S and 28S were represented by one haplotype; ITS2 was represented by two haplotypes (uncorrected p-distances between haplotypes 0.81%), and COI was represented by three haplotypes (uncorrected p-distances between haplotypes 0.16–0.31%): Fig. 10. Paramacrobiotus marchelmoni sp. nov., SEM photographs of paratype (SMNH, SMNHType-10030). A. Details of the body cuticle. B. Leg I. C. Claws of leg III. D. Legs IV. Empty full arrows indicate very fine granules on body cuticle; asterisks indicate leg granulation. European Journal of Taxonomy 1030: 1–52 (2025) 22 – 18S: specimens 22-004, 22-006, 22-007, 22-019, 22-034, 22-110, 22-113; 1302 bp, GenBank accession number PX093665; – 28S: specimens 22-004, 22-019, 22-029, 22-110, 23-015; 921 bp, GenBank accession number PX093651; Fig. 11. Paramacrobiotus marchelmoni sp. nov. eggs. A. SEM photograph (SMNH, SMNH-Type-10030); whole egg. B. DIC photograph in water (SMNH, SMNH-Type-10024); whole egg. C–E. DIC photographs in water (SMNH, SMNH-Type-10024); examples of egg processes. F. SEM photograph (SMNH, SMNH-Type-10030); details of the areolae. G. DIC photograph in water (SMNH, SMNHType-10028); base of the egg processes. Black full arrow indicates areolae surrounding each egg process. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 23 – COI haplotype 1: specimens 22-004, 22-006, 22-007, 22-019, 22-026, 22-029, 22-034, 22-102, 22-108; 636 bp, GenBank accession number PX093656; – COI haplotype 2: specimens 22-106, 22-110, 22-113, 23-041; 636 bp, GenBank accession number PX093657; – COI haplotype 3: specimen 23-015, 636 bp, GenBank accession number PX093658; – ITS2 haplotype 1: specimens 22-029, 22-102; 370 bp; GenBank accession number PX093645; – ITS2 haplotype 2: specimens 22-004, 22-006, 22-007, 22-019, 22-034, 22-110, 22-113; 370 bp, GenBank accession number PX093646. Morphological differential diagnosis Based on the presence of a microplacoid, P. marchelmoni sp. nov. is a member of the richtersi morphogroup (Kaczmarek et al. 2017). Species of this morphogroup may be difficult or sometimes impossible to distinguish morphologically, with distinguishing features frequently limited to a few differences in egg shell morphologies or reproductive biology (Guidetti et al. 2019a). Indeed, P. marchelmoni is very similar to ten species of this group by the following criteria: richtersi-type of egg, with areolae with sculpturing (Kaczmarek et al. 2017), and egg processes with a blunt apex without a cap-like structure. However, P. marchelmoni can be differentiated from each by the following: Paramacrobiotus arduus Guidetti, Cesari, Bertolani, Altiero & Rebecchi, 2019 – the animals of P. marchelmoni sp. nov. lack cuticular bars below the claws of the first three pairs of legs. The eggs of the new species are larger (diameter without processes 67.0–92.4 µm compared to 55.3–62.3 µm in P. arduus), with processes that are surrounded by more areolae (12 compared with 5 “double” areolae in P. arduus) and that are much wider at the base (diameter 21.3–30.0 µm compared to 10.4–16.3 µm in P. arduus) with a more rounded and less narrow apex than those of P. arduus. Paramacrobiotus celsus Guidetti, Cesari, Bertolani, Altiero & Rebecchi, 2019 – the animals of P. marchelmoni sp. nov. lack cuticular bars below the claws of the first three pairs of legs, and the microplacoid has a different shape (heart-shaped with antero-lateral wings compared to drop-shaped in P. celsus). Additionally, the eggs of P. marchelmoni have processes with wider bases (diameter 21.3– 30.0 µm compared to 14.3–18.2 µm in P. celsus). Paramacrobiotus depressus Guidetti, Cesari, Bertolani, Altiero & Rebecchi, 2019 – the animals of P. marchelmoni sp. nov. have much more evident granulation on all legs compared with P. depressus and lack cuticular bars below the claws of the first three pairs of legs. The microplacoid has a different shape (heart-shaped with antero-lateral wings compared to comma-shaped in P. depressus). The eggs are larger in P. marchelmoni (diameter without processes 67.0–92.4 µm compared to 56.2–66.2 µm in P. depressus) with much wider (21.3–30.0 µm compared to 12.4–15.2 µm in P. depressus) egg processes. Paramacrobiotus fairbanksi (following the redescription of Guidetti et al. 2019a) – animals of P. marchelmoni sp. nov. differ from animals of P. fairbanksi in the heart-shaped microplacoid (compared to a comma-shape microplacoid in P. fairbanksi), and the new species is gonochoristic (males are presumed absent for P. fairbanski). The eggs of P. marchelmoni have more areolae surrounding each process (12 compared with 5–6 “double” areolae in P. fairbanksi) and processes with wider bases (21.3– 30.0 µm compared to 10.9–20.8 µm in P. fairbanksi) and smoother, more rounded apexes. Paramacrobiotus gerlachae (Pilato, Binda & Lisi, 2004) – the animals of P. marchelmoni sp. nov. differ from the animals of P. gerlachae by the absence of cuticular bars near the lunules of legs I–III (present in P. gerlachae); by the cuticular granulation on legs I–III (absent in P. gerlachae); and by the more distinct granulation on leg IV (granulation very faint in P. gerlachae). The egg processes are wider in P. marchelmoni (base diameters 21.3–30 µm compared with 16.8–18.7 µm in P. gerlachae). European Journal of Taxonomy 1030: 1–52 (2025) 24 Paramacrobiotus halei (Bartels, Pilato, Lisi & Nelson, 2009) – animals of P. marchelmoni sp. nov. differ from animals of P. halei by the absence of the cuticular tubercles (present in P. halei); the narrower buccal tube (pt 18.1–23.8 compared with pt 26.5–28.6 in P. halei); and the longer internal claw II (pt 21.4–30.0 compared with pt 20.4–21.1 in P. halei). The eggs of P. marchelmoni are smaller (full diameter 92.5–115.0 µm compared with 117.0–121.0 µm in P. halei) with processes with smoother, more rounded apexes. Paramacrobiotus pius Lisi, Binda & Pilato, 2016 – animals of P. marchelmoni sp. nov. differ from animals of P. pius in the lack of cuticular bars below the claws on the first three pair of legs (present in P. pius), the longer third macroplacoid (pt 18.3–29.4 compared to 14.2–14.6 in P. pius) and the longer macroplacoid/placoid rows (pt 52.1–75.7/69.5–95.2 compared to pt 41.4–43.1/53.0–56.2 in P. pius). The eggs of P. marchelmoni have processes with smooth apices (compared to apices with short spines in P. pius) and are surrounded by more numerous areolae (12 compared to 5 “double” areolae in P. pius). Paramacrobiotus richtersi (Murray, 1911) (following the redescription of Guidetti et al. 2019a) – the animals of P. marchelmoni sp. nov. differ from the animals of P. richtersi in the undivided medioventral crest in the third band of the OCA and the lack of cuticular bars below the claws of the first three pairs of legs (bars present in P. richtersi). The eggs of P. marchelmoni differ in the processes, which are shorter (10.0–16.5 µm compared to 17.1–22.1 µm in P. richtersi) and wider (diameter 21.3–30.0 µm compared to 17.1–21.2 µm in P. richtersi) and thus have a stouter appearance than those of P. richtersi. Paramacrobiotus sklodowskae (Michalczyk, Kaczmarek & Węglarska, 2006) – the animals of P. marchelmoni sp. nov. differ from the animals of P. sklodowskae by the absence of eyespots (present in P. sklodowskae); by the more anteriorly inserted stylet support (pt 72.3–80.6 compared with pt 81.8– 85.2 in P. sklodowskae); and by the larger third macroplacoid (pt 18.3–29.4 compared to pt 16.7–18.0 in P. sklodowskae). The eggs are differentiated by the process surfaces, which are always smooth in P. marchelmoni (ring folds present in P. sklodowskae). Paramacrobiotus spatialis Guidetti, Cesari, Bertolani, Altiero & Rebecchi, 2019 – the animals of P. marchelmoni sp. nov. possess an undivided medioventral crest in the third band of the OCA (subdivided into three round teeth in P. spatialis). The eggs of P. marchelmoni have wider processes (21.3–30.0 µm compared to 15.2–20.4 µm in P. spatialis) with smooth apices (compared to apices with tubercles as in P. spatialis). Discussion Macrobiotus Macrobiotus vattenrikense sp. nov. was recovered as sister to M. mileri, and together formed a clade (= Macrobiotus “clade B”) with M. annewintersae Vecchi & Stec, 2021, M. engbergi Stec, Tumanov & Kristensen, 2020, M. caelestis Coughlan, Michalczyk & Stec, 2019, 5 species of the persimilispolonicus complex (Bertolani et al. 2023), 4 species of the pallarii complex (Stec et al. 2021b) and species of Xerobiotus. Macrobiotus vattenrikense and M. mileri share similar morphologies of the egg chorion: very small pores surrounding the egg processes are visible with SEM, but the egg chorion may appear solid under light microscopy. Very small pores (“micropores”; Coughlan et al. 2019) were also described occasionally (although not always) occurring between the processes on the egg chorion of M. caelestis. All other species of the clade lack all pores, including pores visible only with SEM, while species with pores that are clearly visible with both light microscopy and SEM are recovered only in Macrobiotus “clade A”. Further, disk morphology is quite variable within the clade, with elongated arms in M. annewintersae, wide and flat disks in M. caelestis, reduced disks in M. mileri, serrated/indented disks in M. engbergi and indented disks in M. vattenrikense and the other species of the persimilispolonicus complex. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 25 Seven species of Macrobiotus have now been reported from Sweden: M. echinogenitus Richters, 1903; M. hufelandi C.A.S. Schultze, 1834, although the records of this species before its redescription by Bertolani & Rebecchi (1993) have to be confirmed; M. macrocalix Bertolani & Rebecchi, 1993; M. persimilis Binda & Pilato, 1972; M. polonicus Pilato, Kaczmarek, Michalczyk & Lisi, 2003; M. trunovae Biserov, Pilato & Lisi, 2011; and M. vattenrikense sp. nov. (Richters 1904; Carlzon 1909; Thulin 1911; Durante Pasa & Maucci 1979; Sohlenius et al. 1997; Jönsson 2003, 2007; Massa et al. 2021; Guidetti et al. 2025). Two additional species designated nomen inquirendum (Stec et al. 2021a), M. brevipes Mihelčič, 1971 and M. longipes Mihelčič, 1971, and five with partial or uncertain identifications: M. aff. nelsonae, M. aff. polonicus, M. aff. wandae, M. cf. polonicus, and M. cf. terminalis, have also been documented for the country (Mihelčič 1971; Jönsson 2007; Massa et al. 2021; Vecchi & Stec 2021). Paramacrobiotus Paramacrobiotus marchelmoni sp. nov. was described and P. fairbanksi reported from Sweden for the first time. Although the distribution of P. marchelmoni is confirmed only by molecular data, it is of interest that while most species of Paramacrobiotus have restricted geographical ranges, with many endemic to only a single type location (Guidetti et al. 2019a; Kayastha et al. 2023c; Gąsiorek 2024), both species reported here have larger distributions with relatively low intraspecific haplotype diversity even between distant populations (e.g., up to 0.8% for P. marchelmoni and 0.7% for P. fairbanksi for COI; Supp. file 2: sheet 5). Populations of P. marchelmoni occur in Sweden, Spain (“Tar407”, originally misidentified as Macrobiotus pallarii; Stec et al. 2021b) and Hungary (Paramacrobiotus sp. “HU.012”; Stec et al. 2020c), while the presence of P. fairbanksi has been confirmed in Antarctica (Kaczmarek et al. 2020b), Denmark (Gąsiorek et al. 2024), Finland (Vecchi et al. 2024b), Italy (Guidetti et al. 2019a), Poland (Stec et al. 2020c), Spain (Guil & Giribet 2012; Guidetti et al. 2019a), USA (Alaska; Schill et al. 2010) and now Sweden. Reproductive mode has been hypothesized to be one important indicator of biogeographic range for tardigrades (Guidetti et al. 2016, 2019a; Gąsiorek 2024). Asexually reproducing species are generally predicted to have wider distributions than sexual species since they are better able to colonize new areas easily without being subjected to bottleneck effects or outbreeding depression (Artois et al. 2012; Tilquin & Kokko 2016). Following this reasoning, it is not so surprising that asexually reproducing species such as P. fairbanksi and P. gadabouti are known from multiple zoogeographic realms (Guidetti et al. 2019a; Stec et al. 2020c; Kayastha et al. 2023b; this study) while other bisexual species of the genus are locally restricted (Guidetti et al. 2019a; Gąsiorek 2024). Nevertheless, P. marchelmoni sp. nov. is bisexual and has a range that extends at least across Europe. Similar examples exist for other tardigrades, e.g., in Macrobiotus with the bisexual species Macrobiotus vladimiri Bertolani, Biserov, Rebecchi & Cesari, 2011 and M. macrocalix being found within a broad range of localities within Europe (Cesari et al. 2009; Stec et al. 2021a). In addition to reproductive mode, anhydrobiotic ability has also been theorized to have a significant impact on distribution range as being able to stay anhydrobiotic longer with a high survival rate will increase the potential to disperse over a larger area (Gasiorek 2024). Stec et al. (2020c) hypothesized that the wide distribution patterns of P. fairbanksi as well as other tardigrade species known from more than one zoogeographic realm were due to human-mediated dispersion, since their records come from highly populated and touristic locations. Though it is extremely difficult to quantify exactly how the dispersal of P. fairbanksi or any species of tardigrade is influenced by anthropogenic factors, neither the KVBR nor especially Antarctica would likely qualify as highly populated (in 2023, the density of Kristianstad Municipality, for instance, was 69 persons/km 2 [Statistiska Centralbyrån, Sweden] compared to, e.g., 387 persons/km 2 in Fairbanks, Alaska [United States Census Bureau, USA]). The explanation for the current correlation between populated, touristy areas and records of P. fairbanksi is perhaps better attributed to geographical sampling bias. It is a well- European Journal of Taxonomy 1030: 1–52 (2025) 32 Michalczyk Ł. & Kaczmarek Ł. 2017. The Macrobiotus hufelandi group (Tardigrada) revisited. Zootaxa 4363: 101–123. https://doi.org/10.11646/zootaxa.4363.1.4 Mihelčič F. 1971. Susswassertardigraden aus Nordeuropa. 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Zootaxa 4196 (4): 498–510. https://doi.org/10.11646/zootaxa.4196.4.2 Printed versions of all papers are deposited in the libraries of three of the institutes that are members of the EJT consortium: Muséum national dʼHistoire naturelle, Paris, France; Royal Museum for Central Africa, Tervuren, Belgium; Royal Belgian Institute of Natural Sciences, Brussels, Belgium. The other members of the consortium are: Meise Botanic Garden, Meise, Belgium; Natural History Museum of Denmark, Copenhagen, Denmark; Naturalis Biodiversity Center, Leiden, the Netherlands; Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain; Leibniz Institute for the Analysis of Biodiversity Change, Bonn – Hamburg, Germany; National Museum of the Czech Republic, Prague, Czech Republic; The Steinhardt Museum of Natural History, Tel Aviv, Israël. Supplementary files Supp. file 1. Photograph of the location where the samples were taken. https://doi.org/10.5852/ejt.2025.1030.3135.13969 Supp. file 2. Molecular account. https://doi.org/10.5852/ejt.2025.1030.3135.13971 Sheet 1. Primers and PCR protocols used in this study. Sheet 2. Models selected for each gene and dataset in the ML analyses. Sheet 3. Pairwise genetic distances of COI sequences within and between species of Macrobiotus, as defined by mPTP analyses. n/a is listed when only a single sequence was analyzed. Sheet 4. Pairwise genetic distances of ITS2 sequences within and between species of Macrobiotus, as defined by mPTP analyses. n/a is listed when only a single sequence was analyzed. Sheet 5. Pairwise genetic distances of COI sequences within and between species of Paramacrobiotus, as defined by mPTP analyses. n/a is listed when only a single sequence was analyzed. HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 37 Sheet 6. Pairwise genetic distances of ITS2 sequences within and between species of Paramacrobiotus, as defined by mPTP analyses. n/a is listed when only a single sequence was analyzed. Supp. file 3. COI gene tree of Macrobiotidae Thulin, 1928. https://doi.org/10.5852/ejt.2025.1030.3135.13973 Supp. file 4. 18S gene tree of Macrobiotidae Thulin, 1928. https://doi.org/10.5852/ejt.2025.1030.3135.13975 Supp. file 5. ITS2 gene tree of Macrobiotidae Thulin, 1928. https://doi.org/10.5852/ejt.2025.1030.3135.13977 Supp. file 6. 28S gene tree of Macrobiotidae Thulin, 1928. https://doi.org/10.5852/ejt.2025.1030.3135.13979 Supp. file 7. Paramacrobiotus fairbanksi Schill, Förster, Dandekar & Wolf, 2010 collected from Sweden. A. DIC photograph of whole body. B. DIC photograph of placoids. C. DIC photograph of base of the egg processes. D. SEM photograph of egg processes and areolae. E–G. DIC photographs of egg processes. Black full arrow indicates examples of the “double” areolae that surround each egg process. https://doi.org/10.5852/ejt.2025.1030.3135.13981 Supp. file 8. Macrobiotus aff. nelsonae Guidetti, 1998. A. DIC photograph of specimen in water (SMNH, 22-036); whole body. B. DIC photograph of specimen in water (SMNH, 22-036); macroplacoids. C. DIC photograph of specimen in water (SMNH, 24-085); juvenile hatching from egg. D–E. DIC photograph of specimen in water (SMNH, 24-085); examples of egg processes. F. DIC photograph of specimen preserved in Hoyer’s medium (SMNH, 24-079); claws of leg III. G. DIC photograph of specimen preserved in Hoyer’s medium (SMNH, 24-079); legs IV; white arrow indicates pores on cuticle, asterisks indicate large granulation. H. DIC photograph of specimen in water (SMNH, 24-085); egg chorion; black arrows indicate oval areolae surrounding processes. https://doi.org/10.5852/ejt.2025.1030.3135.13983 Supp. file 9. Tenuibiotus sp., DIC photographs of specimen in water (SMNH, 22-109). A. Whole body. B. Pharynx and macroplacoids, white arrowhead indicates deep constriction of the first macroplacoid. C. Claws of leg I. D. Claws of leg IV. https://doi.org/10.5852/ejt.2025.1030.3135.13985 Supp. file 10. Raw morphometric measurements for specimens of Macrobiotus vattenrikense sp. nov. https://doi.org/10.5852/ejt.2025.1030.3135.13987 Supp. file 11. Raw morphometric measurements for specimens of Paramacrobiotus marchelmoni sp. nov. https://doi.org/10.5852/ejt.2025.1030.3135.13989 European Journal of Taxonomy 1030: 1–52 (2025) 38 Appendix 1 (continued on next 14 pages). GenBank Accession numbers for COI, 18S, ITS, and 28S sequences of all specimens analysed in this study. New sequences are highlighted in red. Taxon Specimen COI 18S ITS 28S Taxon name in GenBank Notes Reference in GenBank Diaforobiotus islandicus IS.042 MT808072 MT812470 MT812597 MT812461 Diaforobiotus islandicus Stec et al. 2020d Macrobiotus aff. polonicus S165.1 MW593929 MW588026 MW588021 MW588032 Macrobiotus aff. polonicus S165 Vecchi & Stec 2021 Macrobiotus aff. polonicus S165.2 MW593930 MW588027 MW588020 MW588033 Macrobiotus aff. polonicus S165 Vecchi & Stec 2021 Macrobiotus almadai ZYL123 MW990245 MW995180 Macrobiotus almadai Wang et al. (unpubl.) Macrobiotus annewintersae S207.1 MW593927 MW588025 MW588019 MW588030 Macrobiotus annewintersae Vecchi & Stec 2021 Macrobiotus annewintersae S207.2 MW593928 MW588024 MW588018 MW588031 Macrobiotus annewintersae Vecchi & Stec 2021 Macrobiotus ariekammensis ariekammensis NO.393.01 MZ460999 MZ463668 MZ463657 MZ463674 Macrobiotus ariekammensis ariekammensis Stec et al. 2022 Macrobiotus ariekammensis groenlandicus GL.018.04 MZ461006 MZ463664 MZ463654 MZ463679 Macrobiotus ariekammensis groenlandicus Stec et al. 2022 Macrobiotus azzunae C4218_T5 MW698698 Macrobiotus sp. 1 MC-2021 temporary taxon name has not been updated in GenBank at time of writing Marnissi et al. 2021 Macrobiotus azzunae C4218_V4 MW698697 MW695447 MW695454 MW695450 Macrobiotus sp. 1 MC-2021 temporary taxon name has not been updated in GenBank at time of writing Marnissi et al. 2021 Macrobiotus basiatus USA/NEL/1 MT502116 MT498094 MT505165 MT488397 Macrobiotus sp. 1 DG-2020 temporary taxon name has not been updated in GenBank at time of writing Nelson et al. 2020 Macrobiotus birendrai CN8.101 MW656266 MW680641 MW680418 MW680644 Macrobiotus birendrai Kayastha et al. 2021 Macrobiotus caelestis KG.007 MK737922 MK737073 MK737072 MK737071 Macrobiotus caelestis Coughlan et al. 2019 Macrobiotus canaricus ES.004_H1 MH057765 MH063925 MH063928 MH063934 Macrobiotus canaricus Stec et al. 2018c Macrobiotus canaricus ES.004_H2 MH057766 Macrobiotus canaricus Stec et al. 2018c Macrobiotus cf. hufelandi C2959a HQ876590 OP596303 Macrobiotus cf. hufelandi 1 MC-2011 Bertolani et al. 2011 Macrobiotus cf. muralis C3251_2 OP561785 OP596299 Macrobiotus cf. muralis Bertolani et al. 2023 Macrobiotus cf. muralis C3251_3 OP561786 OP596300 Macrobiotus cf. muralis Bertolani et al. 2023 HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 39 Macrobiotus cf. muralis C3251_4 OP561788 Macrobiotus cf. muralis Bertolani et al. 2023 Macrobiotus cf. muralis C3251_5 OP561789 Macrobiotus cf. muralis Bertolani et al. 2023 Macrobiotus cf. muralis C3251_FA OP561787 OP596301 Macrobiotus cf. muralis Bertolani et al. 2023 Macrobiotus cf. nelsonae 1 HQ604965 Macrobiotus Bertolani et al. 2014 Macrobiotus cf. recens ES.006 haplotype 1 MH057768 MH063927 MH063932 MH063936 Macrobiotus cf. recens DS-2018 Stec et al. 2018c Macrobiotus cf. sapiens S12.Mac.1 OK662997 OK663226 OK663215 OK663237 Macrobiotus cf. sapiens Vecchi et al. 2022c Macrobiotus cf. shonaicus MM1-2018 LC431582 LC431591 Macrobiotus cf. shonaicus Matsumoto & Sugiura (unpubl.) Macrobiotus crustulus GF.271 MT260371 MT261912 MT261907 MT261903 Macrobiotus crustulus Stec et al. 2020a Macrobiotus dolosus C3209_2 OP561772 OP596290 Macrobiotus dolosus Bertolani et al. 2023 Macrobiotus dolosus C3209_4 OP561774 Macrobiotus dolosus Bertolani et al. 2023 Macrobiotus dolosus C3209_US2 OP561773 Macrobiotus dolosus Bertolani et al. 2023 Macrobiotus dolosus C3581_V6 OP561775 OP596292 Macrobiotus dolosus Bertolani et al. 2023 Macrobiotus engbergi haplotype 1 MN444824 MN443039 MN443036 MN443034 Macrobiotus engbergi Vecchi et al. 2024b Macrobiotus engbergi haplotype 2 MN444825 MN443037 Macrobiotus engbergi Vecchi et al. 2024b Macrobiotus fontourai C2861_5 OP561783 OP596295 Macrobiotus fontourai Bertolani et al. 2023 Macrobiotus fontourai C2861_US1 OP561784 OP596296 Macrobiotus fontourai Bertolani et al. 2023 Macrobiotus glebkai UA.003 MW246134 MW247177 MW247180 MW247176 Macrobiotus glebkai Kiosya et al. 2021 Macrobiotus hannae PL.010 MH057764 MH063922 MH063923 MH063924 Macrobiotus hannae Nowak & Stec 2018 Macrobiotus hufelandi C2953a HQ876585 OP596302 Macrobiotus hufelandi Bertolani et al. 2023 Macrobiotus hufelandi S605.Mac.1 OK662992 OK663221 OK663210 OK663232 Macrobiotus hufelandi Bertolani et al. 2023 Macrobiotus joannae 1 HQ604974 Macrobiotus joannae Bertolani et al. 2014 Macrobiotus kamilae IN.030 haplotype 1 MK737920 MK737070 MK737067 MK737064 Macrobiotus kamilae Coughlan & Stec 2019 Macrobiotus kathyae US.006.01 PP386934 PP391285 PP391289 PP391287 Macrobiotus sp. MV2024 temporary taxon name has not been updated in GenBank at time of writing Massa & Vecchi 2024 Appendix 1 (continued). European Journal of Taxonomy 1030: 1–52 (2025) 40 Macrobiotus kathyae US.006.02 PP386935 PP391286 PP391290 PP391288 Macrobiotus sp. MV2024 temporary taxon name has not been updated in GenBank at time of writing Massa & Vecchi 2024 Macrobiotus kathyae US.006.03 PP386932 Macrobiotus sp. MV2024 temporary taxon name has not been updated in GenBank at time of writing Massa & Vecchi 2024 Macrobiotus kathyae US.006.04 PP386933 Macrobiotus sp. MV2024 temporary taxon name has not been updated in GenBank at time of writing Massa & Vecchi 2024 Macrobiotus kirghizicus KG.062.01 MZ461002 MZ463666 MZ463659 MZ463672 Macrobiotus kirghizicus Stec et al. 2022 Macrobiotus kosmali M8.1 OP141639 OP142472 OP153786 OP143765 Macrobiotus kosmali Kayastha et al. 2023a Macrobiotus kristenseni C3291_A02_V2 KC193573 KC193577 Macrobiotus kristenseni Guidetti et al. 2013 Macrobiotus kyoukenus C4313_US3 ON809462 ON818314 ON818301 ON818309 Macrobiotus kyoukenus Cesari et al. 2022 Macrobiotus macrocalix PL.110 MH057767 MH063926 MH063931 MH063935 Macrobiotus macrocalix Stec et al. 2018c Macrobiotus margoae US.057 MN888315 MN888368 MN888340 MN888354 Macrobiotus margoae Vecchi & Stec 2021 Macrobiotus margoae US.057.1 MT807927 MT809072 MT809098 MT809084 Macrobiotus margoae Stec et al. 2021b Macrobiotus margoae US.057.3 MT807928 MT809099 Macrobiotus margoae Stec et al. 2021b Macrobiotus mileri IL.001.01 OR544397 OR543312 OR543316 OR543320 Macrobiotus mileri Stec 2024 Macrobiotus mileri IL.001.02 OR544398 OR543313 OR543317 OR543321 Macrobiotus mileri Stec 2024 Macrobiotus mileri IL.001.03 OR544399 Macrobiotus mileri Stec 2024 Macrobiotus mileri IL.001.04 OR544400 Macrobiotus mileri Stec 2024 Macrobiotus noongaris AU.031 MK737919 MK737069 MK737066 MK737063 Macrobiotus noongaris Coughlan & Stec 2019 Macrobiotus ovovittatus GL.001.01 OR544395 OR543311 OR543314 OR543318 Macrobiotus ovovittatus Stec 2024 Macrobiotus pallarii IT.337.1 MT807924 MT809069 MT809094 MT809081 Macrobiotus pallarii Stec et al. 2021b Macrobiotus pallarii IT.337.2 MT807925 MT809070 MT809095 MT809082 Macrobiotus pallarii Stec et al. 2021b Macrobiotus pallarii IT.337.3 MT807926 MT809071 MT809096 MT809083 Macrobiotus pallarii Stec et al. 2021b Macrobiotus papei TZ.027 MH057763 MH063881 MH063921 MH063880 Macrobiotus papei Stec et al. 2018b Macrobiotus paulinae KT951668 KT935502 KT935500 Macrobiotus paulinae Stec et al. 2015 Appendix 1 (continued). HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 41 Macrobiotus polonicus AT.002 haplotype 1 MN888317 MN888369 MN888337 MN888355 Macrobiotus polonicus Vecchi & Stec 2021 Macrobiotus polonicus AT.002 haplotype 2 MN888318 MN888338 Macrobiotus polonicus Vecchi & Stec 2021 Macrobiotus polonicus AT.002 haplotype 3 MN888319 Macrobiotus polonicus Vecchi & Stec 2021 Macrobiotus polonicus SK.003 haplotype 1 MN888320 MN888370 MN888334 MN888356 Macrobiotus polonicus Vecchi & Stec 2021 Macrobiotus polonicus SK.003 haplotype 2 MN888321 MN888333 Macrobiotus polonicus Vecchi & Stec 2021 Macrobiotus polonicus Mac_pol_S218_1 OQ968326 Macrobiotus polonicus Vecchi et al. 2024b Macrobiotus polypiformis haplotype 1 KX810011 KX810008 KX810010 KX810009 Macrobiotus polypiformis Roszkowska et al. 2017 Macrobiotus pseudopallarii ME.007 haplotype 1 MN888316 MN888365 MN888336 MN888351 Macrobiotus pseudopallarii Vecchi & Stec 2021 Macrobiotus pseudopallarii ME.007.2 MT807920 MT809066 MT809078 Macrobiotus pseudopallarii Stec et al. 2021b Macrobiotus pseudopallarii ME.007.3 MT807921 MT809067 MT809091 MT809079 Macrobiotus pseudopallarii Stec et al. 2021b Macrobiotus pseudopallarii ME.007.4 MT807922 MT809068 MT809092 MT809080 Macrobiotus pseudopallarii Stec et al. 2021b Macrobiotus pseudopallarii ME.007.5 MT807923 MT809093 Macrobiotus pseudopallarii Stec et al. 2021b Macrobiotus rebecchii KG.001.01 OP477442 OP479887 Macrobiotus rebecchii Stec 2022b Macrobiotus ripperi FI.066 MN888312 MN888366 MN888343 MN888352 Macrobiotus ripperi Vecchi & Stec 2021 Macrobiotus ripperi FI.066.2 MT807933 MT809076 MT809103 MT809089 Macrobiotus ripperi Stec et al. 2021b Macrobiotus ripperi FI.066.3 MT807934 MT809104 Macrobiotus ripperi Stec et al. 2021b Macrobiotus ripperi FI.066.4 MT807935 MT809105 Macrobiotus ripperi Stec et al. 2021b Macrobiotus ripperi PL.015.1 MT807929 MT809074 MT809100 MT809086 Macrobiotus ripperi Stec et al. 2021b Macrobiotus ripperi PL.015.2 MT807930 MT809101 MT809087 Macrobiotus ripperi Stec et al. 2021b Macrobiotus ripperi PL.015.3 MT807931 Macrobiotus ripperi Stec et al. 2021b Macrobiotus ripperi PL.015.4 MT807932 MT809102 Macrobiotus ripperi Stec et al. 2021b Macrobiotus rybaki GR.011.1 MW593931 MW588029 MW588022 MW588034 Macrobiotus rybaki Vecchi & Stec 2021 Macrobiotus sandrae C2945e HQ876577 Macrobiotus sandrae Bertolani et al. 2011 Macrobiotus sandrae S859.Mac.1 OK662994 OK663223 OK663212 OK663234 Macrobiotus sandrae Vecchi et al. 2022c Macrobiotus sapiens DQ839601 GQ403680 Macrobiotus sapiens Schill et al. 2010 Macrobiotus scoticus KY797267 KY797265 KY797268 KY797266 Macrobiotus scoticus Stec et al. 2017 Appendix 1 (continued). European Journal of Taxonomy 1030: 1–52 (2025) 48 Paramacrobiotus fairbanksi CN8.2 ON911919 ON872387 ON872382 Paramacrobiotus fairbanksi Mioduchowsk et al. (unpubl.) Paramacrobiotus fairbanksi DT174 OP013289 OP035709 Paramacrobiotus fairbanksi Tumanov et al. 2022 Paramacrobiotus fairbanksi DT175 OP013290 OP035710 Paramacrobiotus fairbanksi Tumanov et al. 2022 Paramacrobiotus fairbanksi DT176 OP035711 Paramacrobiotus fairbanksi Tumanov et al. 2022 Paramacrobiotus fairbanksi DT177 OP013291 OP035712 Paramacrobiotus fairbanksi Tumanov et al. 2022 Paramacrobiotus fairbanksi DT181 OP035713 Paramacrobiotus fairbanksi Tumanov et al. 2022 Paramacrobiotus fairbanksi M85.11 ON911920 Paramacrobiotus fairbanksi Mioduchowsk et al. (unpubl.) Paramacrobiotus fairbanksi M85.12 ON911921 ON872383 Paramacrobiotus fairbanksi Mioduchowsk et al. (unpubl.) Paramacrobiotus fairbanksi MN0101 ON911923 ON872389 ON872384 Paramacrobiotus fairbanksi Mioduchowsk et al. (unpubl.) Paramacrobiotus fairbanksi MN0103 ON911922 ON872385 Paramacrobiotus fairbanksi Mioduchowsk et al. (unpubl.) Paramacrobiotus fairbanksi OSPITALETTO_ B-1 MK041011 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi Par_fai_S09_I14 OQ968319 Paramacrobiotus fairbanksi Vecchi et al. 2024b Paramacrobiotus fairbanksi Par_fai_S42_3 OQ968318 Paramacrobiotus fairbanksi Vecchi et al. 2024b Paramacrobiotus fairbanksi Par_fai_S85_1 OQ968320 Paramacrobiotus fairbanksi Vecchi et al. 2024b Paramacrobiotus fairbanksi Par10eggs_ ATN7_1 MN964281 MN960302 MN960306 Paramacrobiotus fairbanksi Kaczmarek et al. 2020b Paramacrobiotus fairbanksi Par10eggs_ ATN7_2 MN964282 MN960303 MN960307 Paramacrobiotus fairbanksi Kaczmarek et al. 2020b Paramacrobiotus fairbanksi Par11eggs_ ATN7_1 MN961616 MN960304 Paramacrobiotus fairbanksi Kaczmarek et al. 2020b Paramacrobiotus fairbanksi PL.018 MH676011 MH664941 MH666090 MH664950 Paramacrobiotus fairbanksi Stec et al. 2020c Paramacrobiotus fairbanksi PL.035 MH676012 MH664942 MH666091 MH664959 Paramacrobiotus fairbanksi Stec et al. 2020c Paramacrobiotus fairbanksi PONDEL-1 MK041009 MK041029 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi PONDEL-2 MK041010 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi RICCO-1 MK041003 Paramacrobiotus fairbanksi Guidetti et al. 2019a Appendix 1 (continued). HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 49 Paramacrobiotus fairbanksi RICCO-2 MK041004 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi RICCO-3 MK041005 MK041027 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi ROCCHETTA-1 MK041006 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi ROCCHETTA-2 MK041007 MK041028 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus fairbanksi ROCCHETTA-3 MK041008 Paramacrobiotus fairbanksi Guidetti et al. 2019a Paramacrobiotus filipi MY.098 haplotype 1 MT260372 MT261913 MT261904 Paramacrobiotus filipi Stec et al. 2020a Paramacrobiotus filipi MY.098 haplotype 2 MT260373 Paramacrobiotus filipi Stec et al. 2020a Paramacrobiotus gadabouti MD50.1 OP394113 OP394210 Paramacrobiotus gadabouti Kayastha et al. 2023b Paramacrobiotus gadabouti MD50.4 OP394114 OP394212 Paramacrobiotus gadabouti Kayastha et al. 2023b Paramacrobiotus lachowskae MF568534 MF568532 MF568535 MF568533 Paramacrobiotus lachowskae Stec et al. 2018e Paramacrobiotus metropolitanus Keio LC649796 LC649794 LC649797 Paramacrobiotus metropolitanus Sugiura et al. 2022 Paramacrobiotus richtersi CLARE_ ISLAND-1 MK040992 MK041023 Paramacrobiotus richtersi Guidetti et al. 2019a Paramacrobiotus richtersi CLARE_ ISLAND-2 MK040993 Paramacrobiotus richtersi Guidetti et al. 2019a Paramacrobiotus richtersi CLARE_ ISLAND-3 MK040994 Paramacrobiotus richtersi Guidetti et al. 2019a Paramacrobiotus richtersi Par_ric_S1868_1 OQ968324 Paramacrobiotus richtersi Vecchi et al. 2024b Paramacrobiotus richtersi S38.Par.1 OK662995 OK663224 OK663213 OK663235 Paramacrobiotus richtersi Vecchi et al. 2022c Paramacrobiotus sp. AU.044 MH675999 MH664932 MH666081 MH664949 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. BR.009 MH676000 MH664934 MH666082 MH664952 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. FR.077 MH676003 MH664935 MH666083 MH664953 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. Group 3 EU038081 GQ403678 Paramacrobiotus richtersi group Guidetti et al. 2009 Paramacrobiotus sp. HU.012 haplotype 1 MH676005 MH664936 MH666084 MH664954 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. HU.012 haplotype 2 MH676006 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. Kenya 2 EU244598 Paramacrobiotus sp. ‘richtersi’ group Schill et al. 2010 Appendix 1 (continued). European Journal of Taxonomy 1030: 1–52 (2025) 50 Paramacrobiotus sp. Kenya 3 EU244599 Paramacrobiotus sp. ‘richtersi’ group Schill et al. 2010 Paramacrobiotus sp. MG.002 MH676008 MH664938 MH666086 MH664956 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. NO.386 MH676009 MH664939 MH666088 MH664957 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. NZ.001 MH676010 MH664940 MH666089 MH664958 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. Par_sp_S175_2 OQ968321 Paramacrobiotus sp. Vecchi et al. 2024b Paramacrobiotus sp. PT.006 MH676013 MH664943 MH666092 MH664960 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. PT.048 haplotype 1 MH676014 MH664944 MH666093 MH664961 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. PT.048 haplotype 2 MH676015 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. T3 OP531839 ON923868 Paramacrobiotus sp. Basu et al. 2023 Paramacrobiotus sp. Tar407 FJ435807 FJ435741 FJ435756 Macrobiotus pallarii see Discussion Guil & Giribet 2012 Paramacrobiotus sp. TN.014 MH676016 MH664945 MH666094 MH664962 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. TZ.018 MH676017 MH664933 MH666095 MH664951 Paramacrobiotus sp. Stec et al. 2020c Paramacrobiotus sp. DLS-2024a T82_S135 PP414782 PP416751 PP416753 PP416752 Paramacrobiotus sp. DLS-2024a López-Sandoval et al. 2025 Paramacrobiotus sp. MAC-2014 T1 KF788251 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. MAC-2014 T2 KF788252 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. MAC-2014 T3 KF788253 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. MAC-2014 T4 KF788254 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. MAC-2014 T6 KF788255 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. MAC-2014 T7 KF788256 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. MAC-2014 T8 KF788257 Paramacrobiotus richtersi group sp. 1 MAC-2014 Caicedo et al. 2017 Paramacrobiotus sp. ZY-2020 hp1100404 MT731035 MT723894 Paramacrobiotus sp. ZY-2020 Yuan et al. (unpubl.) Paramacrobiotus sp. ZY-2022c N3 OP870172 ON819001 Paramacrobiotus sp. ZY-2022c Yuan et al. (unpubl.) Appendix 1 (continued). HULTERSTRÖM J. et al., New species of Macrobiotidae (Tardigrada) from Sweden 51 Paramacrobiotus spatialis FORMIGINE-1 MK040995 MK041024 Paramacrobiotus spatialis Guidetti et al. 2009 Paramacrobiotus spatialis FORMIGINE-2 MK040996 Paramacrobiotus spatialis Guidetti et al. 2019a Paramacrobiotus spatialis FORMIGINE-3 MK040997 Paramacrobiotus spatialis Guidetti et al. 2019a Paramacrobiotus spatialis FORMIGINE-4 MK040998 Paramacrobiotus spatialis Guidetti et al. 2019a Paramacrobiotus spatialis GAGGIO-1 MK040999 Paramacrobiotus spatialis Guidetti et al. 2019a Paramacrobiotus spatialis GAGGIO-2 MK041000 Paramacrobiotus spatialis Guidetti et al. 2019a Paramacrobiotus spatialis GAGGIO-3 MK041001 MK041025 Paramacrobiotus spatialis Guidetti et al. 2019a Paramacrobiotus spatialis S107.Par OK662996 OK663225 OK663214 OK663236 Paramacrobiotus spatialis Vecchi et al. 2022c Paramacrobiotus tonollii US.035 MH676018 MH664946 MH666096 MH664963 Paramacrobiotus tonollii Stec et al. 2020c Richtersius coronifer NO.385 MH676053 MH681760 MH681763 MH681757 Richtersius coronifer Stec et al. 2020c Sisubiotus hakaiensis Sis.hak.S1911 OM523181 OM523054 OM523057 OM523059 Sisubiotus hakaiensis Vecchi et al. 2022a Sisubiotus spectabilis FI.067 MN888322 MN888371 MN888331 MN888357 Sisubiotus spectabilis Stec et al. 2021a Tenuibiotus cf. ciprianoi ES.086 MN888328 MN888376 MN888348 MN888361 Tenuibiotus cf. ciprianoi Stec et al. 2021a Tenuibiotus danilovi KG.128 MN888329 MN888377 MN888349 MN888362 Tenuibiotus danilovi Stec et al. 2021a Tenuibiotus sp. 22-109 PX093662 PX093667 PX093652 Tenuibiotus sp. this study Tenuibiotus tenuiformis KG.140 MN888330 MN888378 MN888350 MN888363 Tenuibiotus tenuiformis Stec et al. 2021a Tenuibiotus voronkovi haplotype 1 KX810042 KX810045 KX810046 KX810049 Tenuibiotus voronkovi Zawierucha et al. 2016 Tenuibiotus yeliseii DT422 OR145334 OR142418 OR142424 OR142426 Tenuibiotus sp. 1 DVT-2023a temporary taxon name has not been updated in GenBank at time of writing Tsvetkova & Tumanov 2024 Tenuibiotus zandrae MN444827 MN443040 MN443038 MN443035 Tenuibiotus zandrae Stec et al. 2020c Xerobiotus arenosum C4411_V4 OR397039 OR398024 OR398050 Xerobiotus arenosum Vincenzi et al. 2024 Xerobiotus cf. reductus PL3177_1 OR397050 OR398033 OR398056 Xerobiotus cf. reductus Vincenzi et al. 2024 Xerobiotus euxinus check 1.4 PP469626 PP439986 PP470593 PP440001 Macrobiotus euxinus see Vincenzi et al. 2024 Polishchuk et al. 2024 Xerobiotus euxinus C3834_V4 OR397005 OR398005 OR398119 Macrobiotus euxinus see Vincenzi et al. 2024 Vincenzi et al. 2024 Xerobiotus gretae C4341 G MW581665 MW588434 MW588431 MW588438 Macrobiotus gretae see Vincenzi et al. 2024 Massa et al. 2021 Xerobiotus litus C4383_2 OR397000 OR398002 OR398118 Xerobiotus litus Vincenzi et al. 2024 Appendix 1 (continued). European Journal of Taxonomy 1030: 1–52 (2025) 52 Appendix 1 (continued). Xerobiotus naginae S226.Mac.1 OK662990 OK663219 OK663230 Marobiotus naginae see Vincenzi et al. 2024 Vecchi et al. 2022c Xerobiotus pseudohufelandi C2358-XP1 AY598776 HQ604989 Xerobiotus pseudohufelandi Guidetti et al. 2005 Xerobiotus reductus PL_3176_1 OR397048 OR398028 OR398130 Xerobiotus reductus Vincenzi et al. 2024 Xerobiotus sp. PL.360 MN888325 MN888373 MN888345 MN888358 Xerobiotus sp. Vecchi & Stec 2021 Xerobiotus sp. ZA.373 MN888326 MN888374 MN888346 MN888359 Xerobiotus sp. Vecchi & Stec 2021 Xerobiotus sp. 1 MC-2023a C3306_V1 OR397025 OR398020 OR398123 Xerobiotus sp. 1 MC-2023a Vincenzi et al. 2024