Morphology and Molecular Phylogeny of a New Haptorian Ciliate,Chaenea mirabilis sp. n., with Implications for the Evolution of the Dorsal Brush in Haptorians (Ciliophora,Litostomatea)

We discovered a new haptorian ciliate, Chaenea mirabilis sp. n., in brackish water collected near the town of Busan, Korea. Its morphology was studied using standard taxonomical methods and its phylogenetic relationships were assessed by phylogenetic analysis of the 18S rRNA gene. Chaenea mirabilis is distinguished from all congeners by the combination of the following traits: (i) a narrowly bursiform to flask‐shaped, 60–100 μm long body; (ii) 11–21 doughnut‐shaped or sometimes horseshoe‐shaped macronuclear nodules; (iii) two types of extrusomes: type I is rod‐shaped and 6–8 μm long, while type II is narrowly to broadly teardrop‐shaped and only 1.5–2 μm long; (iv) highly refractive special granules tightly arranged between the first and second brush row, forming a conspicuous bulge; and (v) 12–13 somatic kineties. In the 18S rRNA gene phylogeny, C. mirabilis clustered with full support with other congeners. However, there was no statistical support for classification of Chaenea into the families Fuscheriidae, Acropisthiidae, or Trachelophyllidae, but a sister relationship with the Lacrymariidae could not be excluded. Therefore, we establish a new family, Chaeneidae, within the order Lacrymariida. This affiliation is strongly corroborated by the distinctly subapical dorsal brush bearing cilium‐like bristles.     

Distribution of anammox bacteria in domestic WWTPs and their enrichments evaluated by real-time quantitative PCR

Enrichment of anaerobic ammonium oxidation (anammox) bacteria using five activated sludges in three domestic wastewater treatment plants (WWTPs) were processed in a short term of 70 days and evaluated by real-time quantitative PCR (RTQ-PCR). Before the enrichment, building phylogenetic trees of Planctomycetes phylum in four reactors of sequencing batch reactor (SBR), anoxic and oxic reactors of anaerobic–anoxic–oxic (A2O) process, and rotating biological contactor (RBC) revealed six groups of distantly relative genera of Planctomyces, Pirellula, Gemmata, Isophaera, Candidatus and putative anammox bacteria. All clones of Candidatus sp. were affiliated with anammox bacteria and the majority of anammox clones were related to Planctomycete KSU-1 (AB057453). The discovery of anammox bacteria in raw activated sludges provided a partial rationale for the utilization of activated sludge as a seeding source of the anammox process. To verify the activity of anammox bacteria in the activated sludges, enrichment cultivations were conducted using SBRs. The enrichment of anammox bacteria resulted in the significant anammox activity of three samples. Quantification of 16S rRNA gene of anammox bacteria using RTQ-PCR showed the highest concentration of anammox bacteria of 2.48 ± 0.22 × 10⁹ copies of 16S rRNA gene/mg-volatile suspended solids (VSS), which was the same order of magnitude as that of the referential granular anammox sludge, 6.23 ± 0.59 × 10⁹ copies of 16S rRNA gene/mg-VSS, taken from an anammox upflow anaerobic sludge blanket (UASB) reactor. The doubling time of anammox bacteria enriched in this study was 1.18 days. The growth yield of anammox bacteria enriched in this study was 4.75 ± 0.57 × 10⁶ copies of 16S rRNA gene/mg of ammonium- and nitrite-nitrogen, which was similar to 4.50 ± 0.61 × 10⁶ copies of 16S rRNA gene/mg of ammonium- and nitrite-nitrogen for the referential anammox sludge. Substrate uptake rates of three successful enrichments at the end of the enrichment were comparable to those of granular and suspended anammox sludges. Rapid enrichment of anammox bacteria using activated sludge could offer an alternative method for obtaining a large volume of seeding anammox sludge.     

Molecular phylogeny of black fungus gnats (Diptera: Sciaroidea: Sciaridae) and the evolution of larval habitats

The phylogeny of the family Sciaridae is reconstructed, based on maximum likelihood, maximum parsimony, and Bayesian analyses of 4809 bp from two mitochondrial (COI and 16S) and two nuclear (18S and 28S) genes for 100 taxa including the outgroup taxa. According to the present phylogenetic analyses, Sciaridae comprise three subfamilies and two genus groups: Sciarinae, Chaetosciara group, Cratyninae, and Pseudolycoriella group + Megalosphyinae. Our molecular results are largely congruent with one of the former hypotheses based on morphological data with respect to the monophyly of genera and subfamilies (Sciarinae, Megalosphyinae, and part of postulated “new subfamily”); however, the subfamily Cratyninae is shown to be polyphyletic, and the genera Bradysia, Corynoptera, Leptosciarella, Lycoriella, and Phytosciara are also recognized as non-monophyletic groups. While the ancestral larval habitat state of the family Sciaridae, based on Bayesian inference, is dead plant material (plant litter + rotten wood), the common ancestors of Phytosciara and Bradysia are inferred to living plants habitat. Therefore, shifts in larval habitats from dead plant material to living plants may have occurred within the Sciaridae at least once. Based on the results, we discuss phylogenetic relationships within the family, and present an evolutionary scenario of development of larval habitats.     

Parendozoicomonas haliclonae gen. nov. sp. nov. isolated from a marine sponge of the genus Haliclona and description of the family Endozoicomonadaceae fam. nov. comprising the genera Endozoicomonas,Parendozoicomonas, and Kistimonas

Two Gram-stain-negative, facultative anaerobic, motile, rod-shaped strains, S-B4-1U^T and JOB-63a, forming small whitish transparent colonies on marine agar, were isolated from a sponge of the genus Haliclona. The strains shared 99.7% 16S rRNA gene sequence identity and a DNA-DNA hybridization value of 100%, but were differentiated by genomic fingerprinting using rep-PCRs. 16S rRNA gene sequence phylogeny placed the strains as a sister branch to the monophyletic genus Endozoicomonas (Oceanospirillales; Gammaproteobacteria) with 92.3–94.3% 16S rRNA gene sequence similarity to Endozoicomonas spp., 91.9 and 92.1% to Candidatus Endonucleobacter bathymodiolin, and 91.9 to 92.1% to the type strains of Kistimonas spp. Core genome based phylogeny of strain S-B4-1U^T confirmed the phylogenetic placement. Major fatty acids were summed feature 3 (C_16:1 ω7c/C_16:1 ω6c) and 8 (C_18:1 ω7c/C_18:1 ω6c) followed by C_10:0 3-OH, C_16:0, and C_18:0. The G + C content was 50.1–51.4 mol%. The peptidoglycan diamino acid of strain S-B4-1U^T was meso-diaminopimelic acid, the predominant polyamine spermidine, the major respiratory quinone ubiquinone Q-9; phosphatidylethanolamine, phosphatidylglycerol and phosphatidylserine were major polar lipids. Based on the clear phylogenetic distinction, the genus Parendozoicomonas gen. nov. is proposed, with Parendozoicomonas haliclonae sp. nov. as type species and strain S-B4-1U^T (= CCM 8713^T = DSM 103671^T = LMG 29769^T) as type strain and JOB-63a as a second strain of the species. Based on the 16S rRNA gene sequence phylogeny of the Oceanospirillales within the Gammaproteobacteria, the Endozoicomonaceae fam. nov. is proposed including the genera Endozoicomonas, Parendozoicomonas, and Kistimonas as well as the Candidatus genus Endonucleobacter.     

Sarcocystis tupaia,sp. nov., a new parasite species employing treeshrews (Tupaiidae,Tupaia belangeri chinensis) as natural intermediate hosts

The range of vertebrates that serve as intermediate hosts for parasites in the genus Sarcocystis remains incompletely defined. Here, we provide the first report of infections in treeshrews, describe the morphology of encysted parasites using light and transmission electron microscopy, and place this agent within a phylogenetic context by sequencing and comparing its 18 S ribosomal DNA to that of related parasites. Muscle infections were diagnosed in four of 45 wild treeshrews captured in the vicinity of Kunming, Yunnan Province, Mainland China. Thread-like cysts (10.773 ± 2.411 mm in length, 0.106 ± 0.009 mm in width) had walls (0.538–0.746 µm thick) that lacked perpendicular protrusions. The interior of the cyst was packed full with cyst merozoites, the shape of which was typical of Sarcocystis. The primary cyst wall consisted of a thin membrane supported by osmiophilic material, 31–60 nm in thickness. The ground substance was about 105–526 nm thickness. Cysts conformed to typical of ‘type 1’ sarcocysts. Freshly examined and frozen specimens did not differ in their cyst wall structure, however, the appearance of bradyzoites did differ: the conoid, rhoptries and micronemes were all visible in fresh bradyzoites; in stored bradyzoites, by contrast, the rhoptries appeared smaller, and although the conoid was visible, the micronemes were not. 18 S rRNA gene was distinct from any previously reported sequence in GenBank. Their genetic and morphological uniformity suggest that these parasites, derived from treeshrews, represent a single biological species, Sarcocystis tupaia, sp. nov.     

A new genotype of Cryptosporidium from giant panda (Ailuropoda melanoleuca) in China

Fifty-seven fecal samples were collected from giant pandas (Ailuropoda melanoleuca) in the China Conservation and Research Centre for the Giant Panda (CCRCGP) in Sichuan and examined for Cryptosporidium oocysts by Sheather's sugar flotation technique. An 18-year-old male giant panda was Cryptosporidium positive, with oocysts of an average size of 4.60 × 3.99 μm (n = 50). The isolate was genetically analyzed using the partial 18S rRNA, 70 kDa heat shock protein (HSP70), Cryptosporidium oocyst wall protein (COWP) and actin genes. Multi-locus genetic characterization indicated that the present isolate was different from known Cryptosporidium species and genotypes. The closest relative was the Cryptosporidium bear genotype, with 11, 10, and 6 nucleotide differences in the 18S rRNA, HSP70, and actin genes, respectively. Significant differences were also observed in the COWP gene compared to Cryptosporidium mongoose genotype. The homology to the bear genotype at the 18S rRNA locus was 98.6%, which is comparable to that between Cryptosporidium parvum and Cryptosporidium hominis (99.2%), or between Cryptosporidium muris and Cryptosporidium andersoni (99.4%). Therefore, the Cryptosporidium in giant pandas in this study is considered as a new genotype: the Cryptosporidium giant panda genotype.     

Morphology and molecular phylogeny of Oxytricha seokmoensis sp. nov. (Hypotrichia: Oxytrichidae), with notes on its morphogenesis

A new hypotrichous ciliate, Oxytricha seokmoensis sp. nov., was discovered in a soil from a forest in South Korea and described based on the observations of living and stained specimens. In addition, phylogenetic analyses were performed using the small subunit ribosomal RNA (18S rRNA) gene sequence. Morphologically, the new species is similar to the O. granulifera-complex in terms of ciliary structure and arrangement of cortical granules, but dorsal kineties 3 and 4 (not completely separated vs. separated) and macronuclear nodules in the cyst (separated vs. fused) differ. Oxytricha seokmoensis is most similar to O. pulvillus, but can be distinguished by the number of adoral membranelles (30–40 vs. 23–27), contractile vacuole (present vs. absent), number of left (27–37 vs. 17–25) and right (27–35 vs. 18–23) marginal cirri, and lepidosomes on the cyst surface (present vs. absent). In a phylogenetic tree, O. seokmoensis is distinctly separated from the O. granulifera clade, but is sister to the Paroxytricha clade. In addition, O. seokmoensis and P. longigranulosa have the smallest genetic difference (d = 0.015, 23 of 1579 nt difference). This close relationship is supported by incomplete dorsal kinety 3 fragmentation and separated macronuclear nodules in resting cysts.     

Morphology of Clapsiella magnifica gen. n., sp. n., a new hypotrichous ciliate with a curious dorsal ciliary pattern

The present work describes the morphology and infraciliature of a new hypotrichous ciliate, Clapsiella magnifica gen. n., sp. n., found in rewetted soil from a temporal pond in Argentina. It was studied by means of live observation and protargol impregnation. Its main diagnostic features are: Flexible hypotrich measuring 250–320 μm × 70–140 μm in vivo; two macronuclear nodules and 4–6 micronuclei. Single contractile vacuole. Cytoplasm transparent, cortical granules absent. Somatic ciliature composed of a tricorona of cirri, three buccal(?) cirri, 6–9 ventral rows, 3–5 right marginal(?) rows, one left marginal row, and 12–17 transverse cirri. Dorsal pattern rather complicated, with about 14 kineties and kinety fragments, with scattered kinetids among them; 17–28 caudal cirri arranged in three rows on dorsal kineties 1, 3, and 7. Remarkably, dorsal kinetids have two or four basal bodies, bearing a stiff bristle arising from left anterior basal body. Adoral zone composed of 70–92 membranelles, occupying about 40% of body length in protargol preparations; paroral and endoral curved, resembling a cyrtohymenid pattern. The peculiar dorsal ciliary arrangement and the unique combination of other characters require the establishment of a new genus for this new species, which is considered incertae sedis in the Hypotricha but possibly related to the oxytrichids.     

A redescription of the oxytrichid Tetmemena pustulata () and notes on morphogenesis in the marine urostylid Metaurostylopsis salina Lei et al., 2005 (Ciliophora,Hypotrichia)

Two hypotrichous ciliates from China were investigated. The common oxytrichid species Tetmemena pustulata (Müller, 1786) Eigner, 1999, isolated from the estuary of the Pearl River in southern China, was investigated with emphasis on its living morphology and infraciliature. Tetmemena pustulata is characterized as follows: body elliptical to obovoid in shape; 75–115 × 40–60 μm in vivo; two macronuclear nodules and two micronuclei; one contractile vacuole left of midline and somewhat ahead of midbody positioned; three frontal, four frontoventral, one buccal, three postoral ventral, two pretransverse ventral and five transverse cirri; cirrus III/2 ahead of level of cirrus IV/3; cirrus IV/2 arranged more anteriorly than cirrus V/4; transverse cirri not forming two distinct groups; three prolonged and widely separated caudal cirri; six dorsal kineties in Oxytricha-pattern with dorsal kineties 3 and 4 bipolar. The marine urostylid species Metaurostylopsis salina Li et al., 2005, isolated from an aquarium in Qingdao, northern China, was investigated with emphasis on its morphogenesis which is characterized by the de novo formation of the oral primordium in the proter and the development of the marginal rows from two anlagen that form within each parental structure separately in both dividers.     

Morphology and phylogeny of Bryophryoides ocellatus n. g., n. sp. (Ciliophora,Colpodea) from in situ soil percolates of Idaho,U.S.A.

We describe the morphology and 18S rDNA phylogeny of Bryophryoides ocellatus n. g., n. sp., a bryophryid ciliate inhabiting in situ soil percolates from Idaho, U.S.A. The new genus is distinguished from other bryophryid genera by a combination of the following features: (1) kreyellid (irregularly meshed) silverline pattern, (2) polymorphic adoral organelles in the preoral suture, (3) absence of vestibular kineties. In phylogenetic analyses, Bryophryoides ocellatus is most closely related to Bryophrya gemmea. The 18S rDNA sequence pairwise distance of 2% between these genera, while similar to that between many colpodidan species, exceeds that between some colpodidan genera (e.g. Mykophagophrys and Pseudoplatyophrya, 1.1%), further supporting establishment of the new genus. Topology hypothesis testing strongly supports the monophyly of the Colpodida including the bryophryids. Despite weak nodal support, tests of topology constraints narrowly reject the non-monophyly of the sequenced Bryophryidae (Bryophrya + Bryophryoides + Notoxoma). Likewise, the monophyletic origin of the sequenced Bryophryidae is indicated in the phylogenetic networks though with low support.     

Morphology and phylogenetic position of the oxytrichid ciliates,Urosoma salmastra (Dragesco and Dragesco-Kernéis, 1986) Berger, 1999 and U. karinae sinense nov. sspec. (Ciliophora,Hypotrichia)

The morphology and infraciliature of two hypotrichous ciliates, Urosoma salmastra and U. karinae sinense nov. sspec., were investigated for populations collected from the surface of intertidal gravel in the Huguang Mangrove Forest, Zhanjiang, China and the upper 10 cm layer of soil in the Sangke Grass Land in the southern part of Gansu Province, China, respectively. Urosoma salmastra is characterized by its elongate-elliptical body with no tail-like structure; two macronuclear nodules; cortical granules colourless, less than 1 μm across, and arranged in short rows; adoral zone occupying 25% of body length in vivo; paroral conspicuously short and located in front of endoral. Urosoma karinae sinense nov. sspec. is characterized by its elongate-elliptical body with no tail; 2–4 macronuclear nodules; cortical granules colourless, less than 1 μm across, and arranged in short rows; adoral zone occupying 30% of body length in vivo; paroral shorter than, and located ahead of endoral. Phylogenetic analyses based on SSU rRNA gene sequence data suggest a close relationship between U. salmastra, U. karinae sinense nov. sspec. and Oxytricha granulifera within the Oxytrichinae assemblage.     

Morphology and small subunit rRNA gene sequence of Uronemita parabinucleata n. sp. (Ciliophora,Uronematidae), with an improved generic diagnosis

The morphology and infraciliature of a new species, Uronemita parabinucleata n. sp., isolated from intertidal sediments in a coastal region in northern China, were investigated using live observation and silver impregnation methods. The new species is characterized by an in vivo body size of about 20–50 × 10–25 μm, 22 or 23 somatic kineties, two macronuclear nodules, and one caudal cilium. Its small subunit ribosomal RNA gene (SSU rDNA) was sequenced and compared with those of other Uronemita species to reveal nucleotide differences. Phylogenetic analyses indicated that Uronemita is monophyletic and that the new species clusters with its congener Uronemita filificum, with full support provided by both Bayesian inference and maximum likelihood algorithms. Based on previous studies and the present study, an improved diagnosis of the genus Uronemita is supplied, which has been absent since the establishment of this genus. A key to the Uronemita species is also provided.     

Analysis of Actinobacteria from mould-colonized water damaged building material

Mould-colonized water damaged building materials are frequently co-colonized by actinomycetes. Here, we report the results of the analyses of Actinobacteria on different wall materials from water damaged buildings obtained by both cultivation-dependent and cultivation-independent methods. Actinobacteria were detected in all but one of the investigated materials by both methods. The detected concentrations of Actinobacteria ranged between 1.8 × 10⁴ and 7.6 × 10⁷ CFU g^?1 of investigated material. A total of 265 isolates from 17 materials could be assigned to 31 different genera of the class Actinobacteria on the basis of 16S rRNA gene sequence analyses. On the basis of the cultivation-independent approach, 16S rRNA gene inserts of 800 clones (50%) were assigned to 47 different genera. Representatives of the genera Streptomyces, Amycolatopsis, Nocardiopsis, Saccharopolyspora, Promicromonospora, and Pseudonocardia were found most frequently. The results derived from both methods indicated a high abundance and variety of Actinobacteria in water damaged buildings. Four bioaerosol samples were investigated by the cultivation-based approach in order to compare the communities of Actinobacteria in building material and associated air samples. A comparison of the detected genera of bioaerosol samples with those directly obtained from material samples resulted in a congruent finding of 9 of the overall 35 detected genera (25%), whereas four genera were only detected in bioaerosol samples.     

Applicability of massively parallel sequencing on monitoring harmful algae at Varna Bay in the Black Sea

In this study the plankton diversity in 13 environmental samples from Varna Bay (in the western Black Sea) was analyzed using massively parallel sequencing (MPS). This preliminary study was undertaken to assess the potential of this technology for future implementation in monitoring programs in the Black Sea. Amplicon sequences of the 18S rRNA gene (V4-5 regions) were obtained using the Illumina MiSeq 250PE platform. A total of 1137 operational taxonomic units (OTUs) were obtained among which 242 OTUs with >0.990 BLAST top hit similarity (21.3% of all detected OTUs) closely related to sequences belonging to −protists. A large portion (175 OTUs = 72.3%) was identified at the species levels, including species typical for the Bulgarian Black Sea plankton community, as well as many that haven’t been reported earlier in the Bulgarian Black Sea coast (124 OTUs = 51.2%). Dinoflagellates were represented by the highest species number (77 OTUs comprising 31.8% of protist species), with dominant genera Gyrodinium and Heterocapsa. The present survey revealed the presence of 12 species listed as harmful, some of which have been previously overlooked, such as Cochlodinium polykrikoides, Karenia bicuneiformis, and Karlodinium veneficum. Species identification was possible for 10.3–36.0% of the detected OTUs in the six major supergroups. The frequency in Rhizaria was significantly lower than that in other major groups (p < 0.05–0.01), implying difficulties in the classification from morphology-based observations. The metagenetic data had an insufficient resolution of the 18S rRNA gene for species identification in many genera. These issues may hamper the implementation of MPS-based surveys for plankton monitoring, especially for detecting harmful algal blooms (HAB). The sequencing technology is steadily improving and it is expected that sequence length and quality issues will be resolved in the near future. The ongoing efforts to register taxonomic information and quality controls in the international nucleotide sequence databases (INSDs) will be essential for improving taxonomic identification power.     

First report of Rangelia vitalii infection (canine rangeliosis) in Argentina

A 12-year old mixed breed neutered bitch from Misiones, Argentina, was presented with a history of fever and epistaxis. Blood, bone marrow, and lymph node samples were collected for hematology and cytology. Mild regenerative anemia was recorded and large, round, poorly stained piroplasms (> 2.5 μm) were found within erythrocytes in blood and lymph node smears. Nested PCR-RFLP on blood and bone marrow samples was positive for piroplasm DNA. The 18S rRNA gene of piroplasms was targeted. A restriction pattern of a previously unreported piroplasm was observed. The PCR product was sequenced, and the sequence obtained had 99% identity with the Rangelia vitalii sequences from Brazil when compared by BLAST analysis. Further characterization of the detected piroplasm consisted of nearly full-length sequencing (1668 bp) of the 18S rRNA gene of this organism. Those sequences were deposited in GenBank. A phylogenetic analysis indicated that they clustered together with R. vitalii from Brazil but separately from large Babesia species of dogs such as Babesia canis, and from species of Theileria of dogs as well. This is the first report of R. vitalii infection in Argentina, and the first case of canine rangeliosis diagnosed outside Brazil.     

Morphological,ultrastructural and phylogenetic analyses of Myxobolus hilarii n. sp. (Myxozoa,Myxosporea), a renal parasite of farmed Brycon hilarii in Brazil

Myxobolus hilarii n. sp. was described, based on morphology, histology, ultrastructure and 18S rDNA sequencing, infecting the kidney of Brycon hilarii (Valenciennes 1850) (Characiformes: Bryconidae) taken from fish farms in the state of São Paulo, Brazil. Thirteen specimens of B. hilarii were examined and 100% had round, white plasmodia in the kidney. The mature myxospores were rounded, measuring 11.5 ± 0.8 (9.8–13.4) μm in length, 11.0 ± 0.7 (9.7–12.4) μm in width and 7.6 ± 1.0 (6.7–9.0) μm in thickness. Polar capsules were elongated and of equal size, with 6.5 ± 0.4 (6.0–7.2) μm in length and 4.0 ± 0.2 (3.6–5.3) μm in width and their polar filaments had 5 to 7 coils. Histological analysis revealed plasmodial development in the renal tubules, causing compression and deformation of adjacent tissues and destruction of renal tubule cells. Ultrastructural analysis showed direct contact between the plasmodial wall and the host tissue and asynchronous plasmodial development. The phylogenetic analysis of South American myxobolids, based on 18S rDNA sequencing, showed the myxosporeans grouping into two main clades. M. hilarii n. sp. appears as sister species of Myxobolus piraputangae.     

Molecular phylogeny of Arthrotardigrada (Tardigrada)

Tardigrades are microscopic ecdysozoans with a worldwide distribution covering marine, limnic and terrestrial habitats. They are regarded as a neglected phylum with regard to studies of their phylogeny. During the last decade molecular data have been included in the investigation of tardigrades. However, the marine arthrotardigrades are still poorly sampled due to their relative rarity, difficult identification and minute size even for tardigrades. In the present study, we have sampled various arthrotardigrades and sequenced the 18S and partial 28S ribosomal subunits. The phylogenetic analyses based on Bayesian inference and maximum parsimony inferred Heterotardigrada (Arthrotardigrada + Echiniscoidea) and Eutardigrada to be monophyletic. Arthrotardigrada was inferred to be paraphyletic as the monophyletic Echiniscoidea is included within the arthrotardigrades. The phylogenetic positions of Stygarctidae and Batillipedidae are poorly resolved with low branch support. The Halechiniscidae is inferred to be polyphyletic as the currently recognized Styraconyxinae is not part of the family. Archechiniscus is the sister-group to the Halechiniscidae and Orzeliscus is placed as one of the basal halechiniscids. The phylogeny of the included eutardigrade taxa resembles the current molecular phylogenies. The genetic diversity within Arthrotardigrada is much larger (18S 15.1–26.5%, 28S 7.2–20.7%) than within Eutardigrada (18S 1.0–12.6%, 28S 1.3–8.2%). This can be explained by higher substitution rates in the arthrotardigrades or by a much younger evolutionary age of the sampled eutardigrades.