Phylogenomics resolves the higher-level phylogeny of herbivorous eriophyoid mites (Acariformes: Eriophyoidea).

BACKGROUND: Eriophyoid mites (Eriophyoidea) are among the largest groups in the Acariformes; they are strictly phytophagous. The higher-level phylogeny of eriophyoid mites, however, remains unresolved due to the limited number of available morphological characters-some of them are homoplastic. Nevertheless, the eriophyoid mites sequenced to date showed highly variable mitochondrial (mt) gene orders, which could potentially be useful for resolving the higher-level phylogenetic relationships. RESULTS: Here, we sequenced and compared the complete mt genomes of 153 eriophyoid mite species, which showed 54 patterns of rearranged mt gene orders relative to that of the hypothetical ancestor of arthropods. The shared derived mt gene clusters support the monophyly of eriophyoid mites (Eriophyoidea) as a whole and the monophylies of six clades within Eriophyoidea. These monophyletic groups and their relationships were largely supported in the phylogenetic trees inferred from mt genome sequences as well. Our molecular dating results showed that Eriophyoidea originated in the Triassic and diversified in the Cretaceous, coinciding with the diversification of angiosperms. CONCLUSIONS: This study reveals multiple molecular synapomorphies (i.e. shared derived mt gene clusters) at different levels (i.e. family, subfamily or tribe level) from the complete mt genomes of 153 eriophyoid mite species. We demonstrated the use of derived mt gene clusters in unveiling the higher-level phylogeny of eriophyoid mites, and underlines the origin of these mites and their co-diversification with angiosperms.

Long Non-coding RNA LINC00342 Promotes the Proliferation, Invasion, and Migration of Primary Hepatocellular Carcinoma Cells by Regulating the Expression of miRNA-19a-3p, miRNA-545-5p, and miRNA-203a-3p.

This study aimed to investigate the role of the long non-coding RNA (lncRNA) LINC00342-207 (LINC00342) in the development and progression of primary hepatocellular carcinoma (HCC). Forty-two surgically resected HCC tissues and corresponding paracancerous tissues were collected from October 2019 to December 2020 and examined for lncRNA LINC00342, microRNA (miR)-19a-3p, miR-545-5p, miR-203a-3p, cell cycle protein D1 (CyclinD1/CCND1), murine double minute 2 (MDM2), and fibroblast growth factor 2 (FGF2) expression. The disease-free survival and overall survival of patients with HCC were followed up. HCC cell lines and the normal hepatocyte cell line HL-7702 were cultured and the expression level of LINC00342 was measured. HepG2 cells were transfected with LINC00342 siRNA, LINC00342 overexpression plasmid, miR-19a-3p mimics and their corresponding suppressors, miR-545-5p mimics and their corresponding suppressors, and miR-203a-3p mimics and their corresponding suppressors. The proliferation, apoptosis, migration, and invasion of HepG2 cells were detected. Stably transfected HepG2 cells were inoculated into the left axilla of male BALB/c nude mice, and the volume and quality of transplanted tumors as well as the expression levels of LINC00342, miR-19a-3p, miR-545-5p, miR-203a-3p, CCND1, MDM2, and FGF2 were examined. LINC00342 played an oncogenic role in HCC and exhibited inhibitory effects on proliferation, migration, and invasion, and promoted the apoptosis of HepG2 cells. Moreover, it inhibited the growth of transplanted tumors in vivo in mice. Mechanistically, the oncogenic effect of LINC00342 was associated with the targeted regulation of the miR-19a-3p/CCND1, miR-545-5p/MDM2, and miR-203a-3p/FGF2 axes.

The genome sequence of a spider mite, Tetranychus truncatus, provides insights into interspecific host range variation and the genetic basis of adaptation to a low-quality host plant.

The phytophagous mite Tetranychus truncatus is a serious pest in East Asia but has a relatively narrower host range than the pest mite Tetranychus urticae, which can feed on over 1200 plant species. Here, we generated a high-quality chromosomal level genome of T. truncatus and compared it with that of T. urticae, with an emphasis on the genes related to detoxification and chemoreception, to explore the genomic basis underlying the evolution of host range. We also conducted population genetics analyses (in 86 females from 10 populations) and host transfer experiments (in 4 populations) to investigate transcription changes following transfer to a low-quality host (Solanum melongena, eggplant), and we established possible connections between fitness on eggplant and genes related to detoxification and chemoreception. We found that T. truncatus has fewer genes related to detoxification, transport, and chemoreception than T. urticae, with a particularly strong reduction in gustatory receptor (GR) genes. We also found widespread transcriptional variation among T. truncatus populations, which varied in fitness on eggplant. We characterized selection on detoxification-related genes through ω values and found a negative correlation between expression levels and ω values. Based on the transcription results, as well as the fitness and genetic differences among populations, we identified genes potentially involved in adaptation to eggplant in T. truncatus. Our work provides a genomic resource for this pest mite and new insights into mechanisms underlying the adaptation of herbivorous mites to host plants.

Three New Eriophyid Mite Species from China (Acari: Eriophyidae).

Eriophyid mites (Eriophyidae) are strictly phytophagous and are concentrated in Europe, Eastern Asia, Southeast Asia, Western and Eastern North America, Southern India, and New Zealand. South and southwest China are hot spots for eriophyid mite species diversity and endemism. In this study, we describe two new species, Scolotosus ehretussp. nov. on Ehretia acuminata (Boraginaceae) and Neotegonotus ulmchangussp. nov. on Ulmus changii (Ulmaceae), from south and southwest China (the Oriental Region), and one new eriophyid mite, Leipothrix ventricosissp. nov. on Hosta ventricosa (Asparagaceae), from northeast China (the Palearctic Region). All three new eriophyid mite species are distributed in the temperate region of China. We further provided mitochondrial gene (cox1, 12S rRNA) and nuclear gene (18S rRNA, 28S rRNA) sequences for three new species.

Macroevolutionary analyses point to a key role of hosts in diversification of the highly speciose eriophyoid mite superfamily.

The superfamily Eriophyoidea includes >5000 named species of very small phytophagous mites. As for many groups of phytophagous invertebrates, factors responsible for diversification of eriophyoid mites are unclear. Here, we used an inferred phylogeny of 566 putative species of eriophyoid mites based on fragments of two mitochondrial genes and two nuclear genes to examine factors associated with their massive evolutionary diversification through time. Our dated phylogeny indicates a Carboniferous origin for gymnosperm-associated Eriophyoidea with subsequent diversification involving multiple host shifts to angiosperms-first to dicots, and then to monocots or shifts back to gymnosperms-beginning in the Cretaceous period when angiosperms diverged. Speciation rates increased more rapidly in the Eriophyidae + Diptilomiopidae (mostly infesting angiosperms) than in the Phytoptidae (mostly infesting gymnosperms). Phylogenetic signal, speciation rates, dispersal and vicariance results combined with inferred topologies show that hosts played a key role in the evolution of eriophyoid mites. Speciation constrained by hosts was probably the main driver behind eriophyoid mite diversification worldwide. We demonstrate monophyly of the Eriophyoidea, whereas all three families, most subfamilies, tribes, and most genera are not monophyletic. Our time-calibrated tree provides a framework for further evolutionary studies of eriophyoid mites and their interactions with host plants as well as taxonomic revisions above the species level.

Risk factors and survival prediction of pancreatic cancer with lung metastases: A population-based study.

Background: The risk and prognosis of pancreatic cancer with lung metastasis (PCLM) are not well-defined. Thus, this study aimed to identify the risk and prognostic factors for these patients, and establish predictive nomogram models. Methods: Patients diagnosed with PCLM between 2010 and 2016 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Independent risk factors and prognostic factors were identified using logistic regression and Cox regression analyses. Nomograms were constructed to predict the risk and survival of PCLM, and the area under the curve (AUC), C-index, and calibration curve were used to determine the predictive accuracy and discriminability of the established nomogram, while the decision curve analysis was used to confirm the clinical effectiveness. Results: A total of 11287 cases with complete information were included; 601 (5.3%) patients with PC had lung metastases. Multivariable logistic analysis demonstrated that primary site, histological subtype, and brain, bone, and liver metastases were independent risk factors for lung metastases. We constructed a risk prediction nomogram model for the development of lung metastases among PC patients. The c-index of the established diagnostic nomogram was 0.786 (95%CI 0.726-0.846). Multivariable Cox regression analysis demonstrated that primary site, liver metastases, surgery, and chemotherapy were independent prognostic factors for both overall survival (OS) and cancer-specific survival (CSS), while bone metastases were independent prognostic factors for CSS. The C-indices for the OS and CSS prediction nomograms were 0.76 (95% CI 0.74-0.78) and 0.76 (95% CI 0.74-0.78), respectively. Based on the AUC of the receiver operating characteristic (ROC) analysis, calibration plots, and decision curve analysis (DCA), we concluded that the risk and prognosis model of PCBM exhibits excellent performance. Conclusions: The present study identified the risk and prognostic factors of PCLM and further established nomograms, which can help clinicians effectively identify high-risk patients and predict their clinical outcomes.

Effects of hot-air drying temperature on drying characteristics and color deterioration of rape bee pollen.

The effects of different hot-air drying (HAD) temperature (40, 50, 60, and 70 °C) on the drying characteristics, color changes, the contents of α-dicarbonyl compounds (α-DCs), 5-hydroxymethyl furfural (5-HMF) and carotenoids of rape bee pollen were investigated in the study. The results showed that increasing the drying temperature from 40 to 70 °C shortened the drying time by 65 %. HAD caused lower L* and b* values, as well as higher a* values. Browning index and 5-HMF content increased with increasing drying temperature. The relative content of antheraxanthin increased 230 % at 70 °C while lutein and zeaxanthin decreased by 74 and 81 % than that of fresh (non-heated) pollen. The contents of 3-deoxyglucosone, 1-deoxy-2,3-pentosulose, antheraxanthin, and lutein were related to the color deterioration in HAD process in rape bee pollen. This work is of great practical significance to provide scientific basis for quality optimization of bee pollen in the drying process.

Three new species of Calepitrimerus (Acari: Eriophyidae) from China.

The genus Calepitrimerus (Acari: Eriophyoidea) comprise more than 90 extant species. Most species infest angiosperms, while only five were reported from gymnosperms. Herein, we describe and illustrate three new species of the genus Calepitrimerus from China: two from angiosperms, C. huayanlingense sp. nov. on Ficus erecta (Moraceae), C. cryptocaryaer sp. nov. on Cryptocarya concinna (Lauraceae), and one from a gymnosperm, C. liuanense sp. nov. on Cryptomeria japonica (Cupressaceae). All new species were found vagrant on lower surfaces of their hosts leaves, albeit inducing no apparent symptom. A list of Calepitrimerus species in China is tabulated.

Phylogenetic-Related Divergence in Perceiving Suitable Host Plants among Five Spider Mites Species (Acari: Tetranychidae).

Spider mites belonging to the genus Tetranychus infest many important agricultural crops in both fields and greenhouses worldwide and are diversified in their host plant range. How spider mites perceive their suitable host plants remains not completely clear. Here, through two-host-choice designs (bean vs. tomato, and bean vs. eggplant), we tested the efficacies of the olfactory and gustatory systems of five spider mite species (T. urticae, T. truncatus, T. pueraricola, T. piercei, and T. evansi), which differ in host plant range in sensing their suitable host plant, by Y-tube olfactometer and two-choice disc experiments. We found that spider mites cannot locate their suitable host plants by volatile odours from a long distance, but they can use olfactory sensation in combination with gustatory sensation to select suitable host plants at a short distance. Highly polyphagous species displayed strong sensitivity in sensing suitable host plants rather than the lowered sensitivity we expected. Intriguingly, our principal component analyses (PCAs) showed that the similarity among five spider mite species in the performance of perceiving suitable host plants was highly correlated with their relative phylogenetic relationships, suggesting a close relationship between the chemosensing system and the speciation of spider mites. Our results highlight the necessity of further work on the chemosensing system in relation to host plant range and speciation of spider mites.

Phylogeny of Calvittacus Revealing a New Species from China (Acari: Eriophyidae).

Eriophyoid mites (Eriophyoidea) are distributed worldwide and are the largest superfamily in the Acari. After over one and a half centuries of field surveys, regional fauna of eriophyoid mites remains unclear. The genus Calvittacus Xue, Song & Hong 2006 is endemic in the Oriental Region, including four species-C. chenius Xue, Wang, Song & Hong, 2009; C. mollissimus Han, Xue & Hong, 2017; C. regiae Xue, Song & Hong 2006; and C. swidanus Song, Xue & Hong, 2009. In this study, we describe one new species, Calvittacus spectabilus sp. nov., collected on Bougainvillea spectabilis (Nyctaginaceae) from China (the Oriental Region). Phylogenetic analysis based on mitochondrial COI barcode sequences confirmed the C. spectabilus sp. nov., coinciding with the morphological delimitation. We further discussed the potential distribution of the Calvittacus species and underlined the integrative approaches in eriophyoid mite delimitation.

Highly diversified mitochondrial genomes provide new evidence for interordinal relationships in the Arachnida.

Arachnida is an exceptionally diverse class in the Arthropoda, consisting of 20 orders and playing crucial roles in the terrestrial ecosystems. However, their interordinal relationships have been debated for over a century. Rearranged or highly rearranged mitochondrial genomes (mitogenomes) were consistently found in this class, but their various extent in different lineages and efficiency for resolving arachnid phylogenies are unclear. Here, we reconstructed phylogenetic trees using mitogenome sequences of 290 arachnid species to decipher interordinal relationships as well as diversification through time. Our results recovered monophyly of ten orders (i.e. Amblypygi, Araneae, Ixodida, Mesostigmata, Opiliones, Pseudoscorpiones, Ricinulei, Sarcoptiformes, Scorpiones and Solifugae), while rejecting monophyly of the Trombidiformes due to the unstable position of the Eriophyoidea. The monophyly of Acari (subclass) was rejected, possibly due to the long-branch attraction of the Pseudoscorpiones. The monophyly of Arachnida was further rejected because the Xiphosura nested within arachnid orders with unstable positions. Mitogenomes that are highly rearranged in mites but less rearranged or conserved in the remaining lineages point to their exceptional diversification in mite orders; however, shared derived mitochondrial (mt) gene clusters were found within superfamilies rather than interorders, confusing phylogenetic signals in arachnid interordinal relationships. Molecular dating results show that arachnid orders have ancient origins, ranging from the Ordovician to the Carboniferous, yet have significantly diversified since the Cretaceous in orders Araneae, Mesostigmata, Sarcoptiformes, and Trombidiformes. By summarizing previously resolved key positions of some orders, we propose a plausible arachnid tree of life. Our results underline a more precise framework for interordinal phylogeny in the Arachnida and provide new insights into their ancient evolution.

DNA barcoding uncovers cryptic diversity in minute herbivorous mites (Acari, Eriophyoidea).

Eriophyoid mites (Acari: Eriophyoidea) are among the smallest of terrestrial arthropods and the most species-rich group of herbivorous mites with a high host specificity. However, knowledge of their species diversity has been impeded by the difficulty of their morphological differentiation. This study assembles a DNA barcode reference library that includes 1850 mitochondrial COI sequences which provides coverage for 45% of the 930 species of eriophyoid mites known from China, and for 37 North American species. Sequence analysis showed a clear barcode gap in nearly all species, reflecting the fact that intraspecific divergences averaged 0.97% versus a mean of 18.51% for interspecific divergences (minimum nearest-neighbour distances) in taxa belonging to three families. Based on these results, we used DNA barcoding to explore the species diversity of eriophyoid mites as well as their host interactions. The 1850 sequences were assigned to 531 barcode index numbers (BINs). Analyses examining the correspondence between these BINs and species identifications based on morphology revealed that members of 45 species were assigned to two or more BINs, resulting in 1.16 times more BINs than morphospecies. Richness projections suggest that over 2345 BINs occurred at the sampled locations. Host plant analysis showed that 89% of these mites (BINs) attack only one or two congeneric host species, but the others have several hosts. Furthermore, host-mite network analyses demonstrate that eriophyoid mites are high host-specific, and modularity is high in plant-mite networks. By creating a highly effective identification system for eriophyoid mites in the Barcode of Life Data Systems database (BOLD), DNA barcoding will advance our understanding of the diversity of eriophyoid mites and their host interactions.

Population genomic data in spider mites point to a role for local adaptation in shaping range shifts.

Local adaptation is particularly likely in invertebrate pests that typically have short generation times and large population sizes, but there are few studies on pest species investigating local adaptation and separating this process from contemporaneous and historical gene flow. Here, we use a population genomic approach to investigate evolutionary processes in the two most dominant spider mites in China, Tetranychus truncatus Ehara and Tetranychus pueraricola Ehara et Gotoh, which have wide distributions, short generation times, and large population sizes. We generated genome resequencing of 246 spider mites mostly from China, as well as Japan and Canada at a combined total depth of 3,133×. Based on demographic reconstruction, we found that both mite species likely originated from refugia in southwestern China and then spread to other regions, with the dominant T. truncatus spreading ~3,000 years later than T. pueraricola. Estimated changes in population sizes of the pests matched known periods of glaciation and reinforce the recent expansion of the dominant spider mites. T. truncatus showed a greater extent of local adaptation with more genes (76 vs. 17) associated with precipitation, including candidates involved in regulation of homeostasis of water and ions, signal transduction, and motor skills. In both species, many genes (135 in T. truncatus and 95 in T. pueraricola) also showed signatures of selection related to elevation, including G-protein-coupled receptors, cytochrome P450s, and ABC-transporters. Our results point to historical expansion processes and climatic adaptation in these pests which could have contributed to their growing importance, particularly in the case of T. truncatus.

Geography alone cannot explain Tetranychus truncatus (Acari: Tetranychidae) population abundance and genetic diversity in the context of the center-periphery hypothesis.

The center-periphery hypothesis (CPH) states that the genetic diversity, genetic flow, and population abundance of a species are highest at the center of the species' geographic distribution. However, most CPH studies have focused on the geographic distance and have ignored ecological and historical effects. Studies using niche models to define the center and periphery of a distribution and the interactions among geographical, ecological, and historical gradients have rarely been done in the framework of the CPH, especially in biogeographical studies of animal species. Here, we examined the CPH for a widely distributed arthropod, Tetranychus truncatus (Acari: Tetranychidae), in eastern China using three measurements: geographic distance to the center of the distribution (geography), ecological suitability based on current climate data (ecology), and historical climate data from the last glacial maximum (history). We found that the relative abundances of different populations were more strongly related to ecology than to geography and history. Genetic diversity within populations and genetic differentiation among populations based on mitochondrial marker were only significantly related to history. However, the genetic diversity and population differentiation based on microsatellites were significantly related to all three CPH measurements. Overall, population abundance and genetic pattern cannot be explained very well by geography alone. Our results show that ecological gradients explain the variation in population abundance better than geographic gradients and historical factors, and that current and historical factors strongly influence the spatial patterns of genetic variation. This study highlights the importance of examining more than just geography when assessing the CPH.

Two new species of diptilomiopid mites (Acari: Eriophyoidea) from China.

Two new species of the family Diptilomiopidae (Acari: Eriophyoidea) from China are described and illustrated. They are Catarhinus sanguinalus sp. nov. on Digitaria sanguinalis (Poaceae) and Rhyncaphytoptus mandshuricae sp. nov. on Fraxinus mandshurica (Oleaceae). Both new species are vagrant on lower leaf surface. No apparent damage to the host was observed. In addition to the descriptions, a key to Catarhinus species was provided.

Unravelling the phylogeny, cryptic diversity and morphological evolution of Diptilomiopus mites (Acari: Eriophyoidea).

The Eriophyoidea, notable for specific morphological characters (four-legged mites) and gall-formation in host plants (gall mites), is one of the most species-rich superfamilies of Acari. Monophyly of the superfamily Eriophyoidea is accepted by all acarologists; however, monophyly of most genera has not been evaluated in a molecular phylogenetic network. Furthermore, most eriophyoid mites, especially species in the genus Diptilomiopus, are morphologically similar, challenging their identification. Here we test the phylogeny and cryptic diversity of Diptilomiopus species using fragments of two mitochondrial (COI and 12S) and two nuclear (18S and 28S) genes. Our results revealed the monophyly of Diptilomiopus. Sequence distance, barcode gap, and species delimitation analyses of the COI gene allowed us to resolve cryptic diversity of Diptilomiopus species. Additionally, we supposed that characteristics of genu fused with femur on both legs and seta ft' absent on leg II evolved only once within Diptilomiopus, which are potential morphological synapomorphies. In contrast, characteristics of both setae ft' and ft″ divided into a short branch and a long branch were supposed evolving multiple times independently. Our findings contribute to the understanding of phylogeny and morphological evolution of Diptilomiopus species and provide a DNA-based approach for species delimitation of Diptilomiopus mites.

Two new species of eriophyid mites (Acari: Eriophyidae) from Malaysia.

Two new species of the family Eriophyidae (Acari: Eriophyoidea) from Mount Trusmadi, Malaysia, are described and illustrated. They are Neodicrothrix grandcaputus sp. nov. on Stachyurus himalaicus (Stachyuraceae) and Latitudo asiaticis sp. nov. on Psychotria asiatica (Rubiaceae). Both of the two new species are vagrant on the lower leaf surface. No damage to the host was observed. In addition to the description, a key to species of Neodicrothrix is provided.

Mitochondrial variation in small brown planthoppers linked to multiple traits and probably reflecting a complex evolutionary trajectory.

While it has been proposed in several taxa that the mitochondrial genome is associated with adaptive evolution to different climatic conditions, making links between mitochondrial haplotypes and organismal phenotypes remains a challenge. Mitonuclear discordance occurs in the small brown planthopper (SBPH), Laodelphax striatellus, with one mitochondrial haplogroup (HGI) more common in the cold climate region of China relative to another form (HGII) despite strong nuclear gene flow, providing a promising model to investigate climatic adaptation of mitochondrial genomes. We hypothesized that cold adaptation through HGI may be involved, and considered mitogenome evolution, population genetic analyses, and bioassays to test this hypothesis. In contrast to our hypothesis, chill-coma recovery tests and population genetic tests of selection both pointed to HGII being involved in cold adaptation. Phylogenetic analyses revealed that HGII is nested within HGI, and has three nonsynonymous changes in ND2, ND5 and CYTB in comparison to HGI. These molecular changes likely increased mtDNA copy number, cold tolerance and fecundity of SBPH, particularly through a function-altering amino acid change involving M114T in ND2. Nuclear background also influenced fecundity and chill recovery (i.e., mitonuclear epistasis) and protein modelling indicates possible nuclear interactions for the two nonsynonymous changes in ND2 and CYTB. The high occurrence frequency of HGI in the cold climate region of China remains unexplained, but several possible reasons are discussed. Overall, our study points to a link between mtDNA variation and organismal-level evolution and suggests a possible role of mitonuclear interactions in maintaining mtDNA diversity.

Robust Model-Free Adaptive Iterative Learning Control for Vibration Suppression Based on Evidential Reasoning.

Through combining P-type iterative learning (IL) control, model-free adaptive (MFA)control and sliding mode (SM) control, a robust model-free adaptive iterative learning (MFA-IL)control approach is presented for the active vibration control of piezoelectric smart structures.Considering the uncertainty of the interaction among actuators in the learning control process,MFA control is adopted to adaptively adjust the learning gain of the P-type IL control in order toimprove the convergence speed of feedback gain. In order to enhance the robustness of the systemand achieve fast response for error tracking, the SM control is integrated with the MFA control todesign the appropriate learning gain. Real-time feedback gains which are extracted fromcontrollers construct the basic probability functions (BPFs). The evidence theory is adopted to thedesign and experimental investigations on a piezoelectric smart cantilever plate are performed tovalidate the proposed control algorithm. The results demonstrate that the robust MFA-IL controlpresents a faster learning speed, higher robustness and better control performance in vibrationsuppression when compared with the P-type IL control.

Roseovarius tibetensis sp. nov., a halophilic bacterium isolated from Lake LongmuCo on Tibetan Plateau.

Two Gram-stain negative halophilic strains, designated as LM2T and LM4, were isolated from Lake LongmuCo on Tibetan Plateau. These two strains were aerobic, catalaseand oxidase-positive, nonmotile and rod-shaped organisms. Phylogenetic analysis based on 16S rRNA gene sequences indicated that LM2T and LM4 belong to the genus Roseovarius, with Roseovarius tolerans EL-172T (97.3% and 97.4% 16S rRNA gene sequence similarity, respectively) and Roseovarius azorensis SSW084T (95.5% and 95.6% 16S rRNA gene sequence similarity, respectively) as their closest neighbors. Q-10 was the sole respiratory quinone of these two strains. The major fatty acids were C18:1ω7c/C18:1ω6c, C16:0, C19:0 cyclo ω8c, and 11-methyl C18:1ω7c. The polar lipids included phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phospholipid of unknown structure containing glucosamine, and unidentified aminolipid. The DNA G + C content was between 64.2 and 64.5 mol%. DNA-DNA hybridization showed 96.7% relatedness between LM2T and LM4, 24.9% relatedness between LM2T and R. tolerans EL-172T, and 36.3% relatedness between LM4 and R. tolerans EL-172T. Based on phylogenetic analysis, DNA-DNA hybridization, a range of physiological and biochemical characteristics, LM2T and LM4 belong to the same species and were clearly distinguished from the type strains of the genus Roseovarius. It was evident that LM2T and LM4 could be classified as a novel species of the genus Roseovarius, for which the name Roseovarius tibetensis sp. nov. is proposed. The type strain is LM2T (= CGMCC 1.16230T = KCTC 62028T).