New species of oribatid mites (Acari, Oribatida) of the genera Micreremus (Micreremidae) and Phylloribatula (Scheloribatidae) associated with trees in Vietnam

Oribatid mite fauna of Vietnam is most studied among countries of Continental Southeast Asia but due to the brief history of detailed research, discoveries of new species are expected. Descriptions of two new species of oribatid mites (Oribatida) of the family Galumnidae—Flagellozetes (Cosmogalumna) sacculus sp. nov. and F. (C.) lineatus sp. nov.—are presented based on specimens collected from rainforest soil of Bi Dup—Nui Ba National Park (southern Vietnam). F. (C.) sacculus sp. nov. differs from other species by the presence of saccules and rare diamond-shaped granules on pteromorphs. F. (C.) lineatus sp. nov. differs from F. (C.) ekaterinae (Ermilov & Friedrich, 2016) and F. (C.) dongnaiensis (Ermilov & Anichkin, 2013) by the presence of striate pteromorph, genital and anal plates, median pore, and centrodorsal part of notogaster ornamentation represented by neural ridges band.

Two new oribatid mite species—Phauloppia dilatata sp. nov. (Oribatulidae) and Pirnodus partiarus sp. nov. (Oripodidae)—are described, based on adults collected from tree branches of Haldina cordifolia in southern Vietnam. The genus Pirnodus is recorded for the first time in the Oriental region. The generic diagnoses for Phauloppia and Pirnodus are revised. The identification keys to the Oriental representatives of Phauloppia and the known representatives of Pirnodus are provided. Pseudopirnodus madegassus is transferred to Pirnodus; the initial placement of Pirnodus domrowi in Pirnodus is confirmed. http://zoobank.org/urn:lsid:zoobank.org:pub:298B44CE-C965-4B10-8B0F-A3CDB9BAFD57

Oribatid mites are involved in decomposition processes, formation of soil structure and nutrient cycling in most soils worldwide. The main habitats of oribatid mites are litter and soil but they also occur numerously on tree trunks, dead wood, marine intertidal zones and freshwater habitats. Especially in forest ecosystems they reach high local density and diversity and often dominate arthropod fauna in edaphic and arboreal habitats where they form an important part of the food web. Although oribatid mites are often regarded as a functional group of primary decomposers they feed on a wide range of food resources including lichens, mosses, algae, litter, fungi and nematodes. The exceptionally high proportion of oribatid mite species reproducing via parthenogenesis and the co-occurrence with sexual species in the same habitats make oribatid mites an interesting model group for ecological and evolutionary research. In this thesis we investigated oribatid mite density, diversity, community structure and the proportion of parthenogenetic individuals across regions, forests types and habitats. Furthermore, we investigated the importance of root-derived resources for soil living oribatid mite communities by root-trenching, and assessed the trophic diversity on the bark of dead wood using stable isotopes. In Chapter 2 we investigated how oribatid mite communities on the bark of early decaying dead wood are affected by log species (beech vs. oak), forest type (deciduous vs. coniferous) and region (Schorfheide-Chorin, Hainich-Dün and Schwäbische Alb). We further assessed the trophic structure of dead wood communities using stable isotopes (15N and 13C) in one region (Hainich-Dün). The results suggest that dead wood of an early decaying stage is colonized by a mixture of edaphic and arboreal oribatid mite species and only few dead wood specialists. Stable isotope analysis provided evidence that dead wood is colonized by a community of high trophic diversity including lichen, moss, litter and fungal feeders with the latter dominating. Compared to soil, the proportion of parthenogenetic individuals on dead wood was generally low resembling arboreal communities. We showed that oribatid mite assemblages on the bark of dead wood are shaped by log species, the surrounding forest type and the region whereas density was not significantly affected by all three factors. The results indicated that oribatid mite communities on dead wood are shaped by both neutral and niche-based process. In the second study (Chapter 3) we investigated oribatid mite density, community structure and the percentage of parthenogenetic individuals in four different forest types across three regions in Germany in 2008 and once again in 2011. We compared temporal (inter-annual) fluctuations in population densities between sexually and parthenogenetically reproducing species of oribatid mites. Oribatid mite community structure did not differ significantly between years but varied with forest type and region, indicating low species turnover over time. Temporal fluctuations were significantly higher in parthenogenetic as compared to sexual species. The percentage of parthenogenetic individuals was significantly higher in coniferous as compared to beech forests and significantly higher in Schorfheide-Chorin as compared to Hainich-Dün and Schwäbische Alb. The results indicate that parthenogenetic species flourish if populations are controlled by density-independent factors and dominate at sites were resources are plentiful and easily available, such as coniferous forests, and in regions with more acidic soils and thick organic layers, such as Schorfheide-Chorin. However, historical factors also may have contributed to the increased dominance of parthenogenetic species in the Schorfheide-Chorin, since this region was heavily glaciated, and this may have favoured parthenogenetic species. Overall, our study supports the hypothesis that parthenogenetic species benefit from the lack of density-dependent population control whereas the opposite is true for sexual species. In the third study (Chapter 4) we tested the significance of root-derived carbon for oribatid mite communities by interrupting the carbon flux from plants into the soil via root-trenching in two regions in Germany (Schorfheide-Chorin and Hainich-Dün). After one year, root-trenching tended to reduce total oribatid mite densities in Hainich-Dün while it had no overall effect in the Schorfheide-Chorin. Root-trenching primarily reduced densities of soil-living oribatid mites in the Hainich-Dün and primarily litter-living species in Schorfheide-Chorin. Oribatid mite community composition of both regions was not significantly affected by root-trenching. The results suggest that in contrast to previous studies only a minor part of the oribatid mite community benefits directly or indirectly from root-derived resources. The different response of oribatid mites following root-trenching in the two regions indicates that the importance of root-derived resources varies with soil structure, being more intense when litter accumulation is low. Possibly, the weak response to reduced belowground resource input was buffered by internal carbon resources of coarse roots being cut and also by the trophic plasticity of many oribatid mite species.

The species composition of arboreal oribatid mites that live on Siberian pine trees (Pinus sibirica) in the forest-tundra of Western Siberia was examined, specifically of three Siberian pines from two distinct forest stands (six trees in total). Samples of litter were taken near the tree trunk, as well as samples of bark, branches and needles from the tree. In total 144 samples were taken, from which close to 5000 mites were extracted. From the arboreal samples, the mites were extract by heptane flotation. Three species of oribatid mites were recorded for the first time in Russia: Diapterobates brevidentatus, Eueremaeus trionus and Cultroribula berolina. The highest density and the highest dominance index of these species were recorded in arboreal microhabitats. Thirty-one species of oribatid mites were identified in total. No oribatid mites were recovered from the needles of Siberian pine. The density of oribatid mites did not significantly differ among various heights of the crown and trunk. The lowest density of mites was recorded on young branches without needles, whereas other branch hypothetical microhabitats did not significantly differ from each other in terms of oribatid density. The greatest Simpson diversity index was recorded in the plant litter near tree trunks. On trees, the diversity index decreased with the height of the trunk and with the distance of branch sections from the trunk. The dominant species and the degree of their dominance varied among microhabitats and forest stands. Additionally, a high level of dominance of a single oribatid species was observed on tree branches, as well as on the trunk bark located above the bole. In the two forest stands, these species were D. brevidentatus and Ameronothrus dubinini. Based on the analysis of oribatid communities, three microhabitats were identified in the first forest stand: the bole bark, the bark of the trunk above the bole, and the branches. In the second forest stand, bases of tree branches were identified as an additional microhabitat. Oribatids inhabit Siberian pine trees in the severe conditions of the forest-tundra. Arboreal oribatid communities of various microhabitats vary in their qualitative and quantitative characteristics. Also, arboreal and forest litter communities of oribatid mites vary significantly.

The Cantilever Abilities of Snakes

Three new species of oribatid mites (Oribatida) of the superfamily Oripodoidea – Phauloppia differens sp. n. (Oribatulidae), Oripoda operta sp. n. (Oripodidae) and Pirnodus concavus sp. n. (Oripodidae) – are described, based on adults collected from the bark and tree branches of Dipterocarpus alatus and Haldina cordifolia in southern Vietnam.

This paper reassesses the taxonomy and systematics of 11 arboreal snail species in the genus Amphidromus from Vietnam, Cambodia, Indonesia and Laos (A.bozhii Wang, 2019, A.buelowi Fruhstorfer, 1905, A.costifer Smith, 1893, A.haematostoma Möllendorff, 1898, A.ingens Möllendorff, 1900, A.madelineae Thach, 2020, A.metabletus Möllendorff, 1900, A.pankowskianus Thach, 2020, A.placostylus Möllendorff, 1900, A.roseolabiatus Fulton, 1896, and A.thachi Huber, 2015). The taxonomic validity of each species is supported by a phylogenetic analysis of mitochondrial COI and 16S rRNA gene fragments from 17 ingroup taxa. Amphidromusbuelowi was found to comprise two populations from two distant localities, one from Mount Singgalang, West Sumatra, Indonesia and the other from southern Vietnam. The samples from southern Vietnam were previously described as A.asper Haas, 1934 and A.franzhuberi Thach, 2016, but they are now treated as junior synonyms of A.buelowi in this study. In addition, two species from Vietnam are described as new to science, viz. A.asperoides Jirapatrasilp & Lee, sp. nov. and A.ingensoides Jirapatrasilp & Lee, sp. nov., each of which is conchologically comparable to A.buelowi and A.ingens, respectively.

Aim This study investigates the species–area relationship (SAR) for oribatid mite communities of isolated suspended soil habitats, and compares the shape and slope of the SAR with a nested data set collected over three spatial scales (core, patch and tree level). We investigate whether scale dependence is exhibited in the nested sampling design, use multivariate regression models to elucidate factors affecting richness and abundance patterns, and ask whether the community composition of oribatid mites changes in suspended soil patches of different sizes.Location Walbran Valley, Vancouver Island, Canada.Methods A total of 216 core samples were collected from 72 small, medium and large isolated suspended soil habitats in six western redcedar trees in June 2005. The relationship between oribatid species richness and habitat volume was modelled for suspended soil habitat isolates (type 3) and a nested sampling design (type 1) over multiple spatial scales. Nonlinear estimation parameterized linear, power and Weibull function regression models for both SAR designs, and these were assessed for best fit usingR2and Akaike's information criteria (ΔAIC) values. Factors affecting oribatid mite species richness and standardized abundance (number per g dry weight) were analysed byanovaand linear regression models.Results Sixty‐seven species of oribatid mites were identified from 9064 adult specimens. Surface area and moisture content of suspended soils contributed to the variation in species richness, while overall oribatid mite abundance was explained by moisture and depth. A power‐law function best described the isolate SAR (S = 3.97 × A0.12,R2 = 0.247,F1,70 = 22.450,P < 0.001), although linear and Weibull functions were also valid models. Oribatid mite species richness in nested samples closely fitted a power‐law model (S = 1.96 × A0.39,R2 = 0.854,F1,18 = 2693.6,P < 0.001). The nested SAR constructed over spatial scales of core, patch and tree levels proved to be scale‐independent.Main conclusions Unique microhabitats provided by well developed suspended soil accumulations are a habitat template responsible for the diversity of canopy oribatid mites. Species–area relationships of isolate vs. nested species richness data differed in the rate of accumulation of species with increased area. We suggest that colonization history, stability of suspended soil environments, and structural habitat complexity at local and regional scales are major determinants of arboreal oribatid mite species richness.

A list of 40 oribatid mite (Oribatida) species belonging to 34 genera and 20 families, collected from the mangroves in the Can Gio Biosphere Nature Reserve, southern Vietnam, is presented. One new species of Polyxylobates (Haplozetidae) is described: P. paradiversiporosus Ermilov, Salavatulin et Khaustov sp. n. The new species differs from the known representatives of the genus in the number of notogastral setae and the absence of a translamella. A new generic diagnosis of Polyxylobates is provided.

An annotated checklist of oribatid mite taxa from acacia and pine plantations of Dong Nai Culture and Nature Reserve (Southern Vietnam) is presented. The species Ctenacarus araneola, Nehypochthonius porosus,Scheloribates mahunkai, Scheloribates kraepelini, Indoribates panabokkei, genera Ctenacarus,Nehypochthonius and families Ctenacaridae and Nehypochthoniidae are first records from Vietnam, and of these Nehypochthoniidae, Nehypochthonius and Nehypochthonius porosus are first records from the Oriental region. A new oribatid mite species, Galumna (Cosmogalumna) dongnaiensis sp. nov. (Galumnidae), is described from soil in a pine plantation. The new species is distinguishable from all species of the subgenus Galumna (Cosmogalumna) by the sculpturing of the prodorsum and pteromorphs and the number of notogastral porose areas.

BackgroundClimatic and geographical characteristics may alter the plant distribution and thereby the patterns of allergens.ObjectiveTo evaluate the profile of allergen sensitization in patients in southern Vietnam and its association with allergic diseases.MethodsWe collected data of 423 patients who visited the Unit of Allergy and Clinical Immunology, University Medical Center, Vietnam from 2014 to 2021, from their medical records. Patients underwent skin prick tests to the 12 most common aeroallergens. Clinical evaluation and diagnosis of allergic diseases was done in consert with their allergen sensitization status.ResultsMites and cockroach were the most prevalent sensitizing allergens, with the sensitization prevalences as followed: Dermatophagoides farinae (Df) (59.8%), Dermatophagoides pteronyssinus (Dp) (50.4%), Blomica tropicalis (Bt) (49.6%), storage mites mix (10.4%), and cockroach (10.2%). Sensitization to Df was more predominant in males than in females (66% vs 54.1%). Dp-sensitized patients were younger than non-sensitized patients (29.01 ± 13.60 vs. 32.17 ± 14.89) whereas storage mites-sensitized patients were older than the non-sensitized groups (36.25 ± 13.53 vs. 28.76 ± 13.39) (p < 0.05 for all). A considerable proportion of patients with urticaria, allergic rhinitis, and atopic dermatitis were sensitized to mites. Polysensitization to different species of house dust mites (Dp, Df) and storage mites (Bt) was prevalent among patients sensitized to any kind of mites.ConclusionsAmong people living in southern Vietnam, HDM mites, and cockroach were the predominant allergens. Further studies on the factors regulating the association between allergen sensitization with allergic diseases and polysensitization are crucial.

Two species of oribatid mites (Acari: Oribatida), Pergalumna pseudosejugalis sp. nov. and Oribatella gerdweigmanni sp. nov. are described from Bu Gia Map National Park (Southern Vietnam). Pergalumna pseudosejugalis sp. nov. is most similar morphologically to P. crassipora Mahunka, 1995, but it differs from the latter in the microfoveolate integument, presence of pseudosejugal line, of a pair of transversal striate bands on ventral side and of median pore, and by shorter lamellar setae. Oribatella gerdweigmanni sp. nov. is most similar morphologically to O. sculpturata Mahunka, 1987, but it differs from the latter in a smaller body size, a microfoveolate integument, the presence of the translamella, more short lateral and medial lamellar dens, and sparse striae in an epimeral region.

The description of a new species of oribatid mites (Oribatida) of the family ZetorchestidaeZetorchestes krisperi sp. nov.is proposed based on adult and tritonymph specimens collected from rainforest soil of Bi Dup-Nui Ba National Park (southern Vietnam). We also review the distinguishing characteristics for Zetorchestes species and present an identification key to Zetorchestes species of the world. Diagnostic features of Zetorchestes nymphs are discussed.

Two new species of oribatid mites, Suctobelbella (Ussuribata) phylliformis sp. n. (Suctobelbidae) and Neoribates (Neoribates) paratuberculatus sp. n. (Parakalummidae), are described from ferralitic soil of polydominant forest in Dong Nai Culture and Nature Reserve, southern Vietnam. Suctobelbella (Ussuribata) phylliformis sp. n. is similar morphologically to S. (U.) separata Mahunka, 2001, however, the new species differs from the latter by the number of genital and adanal setae, the morphology of the knob-like tubercle and the number of lateral prodorsal teeth. Neoribates (Neoribates) paratuberculatus sp. n. is similar morphologically to N. (N.) tuberculatus Willmann, 1956, however, the new species differs from the latter by the smaller body size, density of tubercles on pteromorphs and the morphology of bothridial setae. The validity of Suctobelbella (Ussuribata) is discussed; an identification key to all species of this subgenus is given.

Four new species of oribatid mites, Unguizetes cattienensis sp. nov. (Mochlozetidae), Gigantoppia zryanini sp. nov. (Granuloppiidae), Caucasiozetes frankeae sp. nov. (Microzetidae) and Otocepheus (Acrotocepheus) vietnamicus sp. nov. (Otocepheidae) from forest soil, litter and decaying wood of Cat Tien National Park in southern Vietnam are described. The representative of the genus Gigantoppia as well as Unguizetes sphaerula is recorded for the first time in Vietnam, and the genus Caucasiozetes is firstly recorded in the Oriental Region. A new generic diagnosis of Caucasiozetes is presented, and an identification key to the Vietnamese species of Otocepheus (Acrotocepheus) is presented.