Merging Quinoxalin-2(1H)-ones Excitation with Cobaloxime Catalysis: C3 Alkylation of Quinoxalin-2(1H)-ones with Unactivated Alkyl Iodides and Carboxylic Acids under Light.

Reported herein is a practical, economical, and efficient construction of 3-alkylated quinoxalin-2(1H)-ones with alkyl carboxylic acids and alkyl iodides by quinoxalin-2(1H)-one excitation and cobaloxime catalysis. Primary, secondary, and tertiary alkyl iodides and carboxylic acids all could be efficiently transferred into target products with excellent functional group tolerance. Mechanism studies reveal that the quinoxalin-2(1H)-one derivatives could be directly excited and yield alkyl carbon radicals from alkyl carboxylic acids and alkyl iodides with the aid of the cobaloxime complex.

Species diversity and related ecology of chiggers on small mammals in a unique geographical area of Yunnan Province, southwest China.

Chiggers are common ectoparasites and the exclusive vector of scrub typhus. Based on previous investigations from a unique geographical area in Yunnan Province of southwest China, the Three Parallel Rivers Area, we retrospectively studied the species diversity and related ecology of chiggers on rodents and other small mammals. A very high species diversity of 120 chigger species was identified. Five dominant chigger species accounted for 59.4% (5238/8965) of total chiggers, and among them Leptotrombidium scutellare is the second major vector of scrub typhus in China. Species diversity of the chigger community fluctuates greatly in different altitudinal and latitudinal gradients. There are significant differences in species composition, species diversity and dominant species of chiggers among hosts with apparent community heterogeneity. Based on the species abundance distribution, the expected total number of chigger species was estimated to be 170, 50 more than the number of actually collected species; this further indicates a very high chigger species diversity in this area. The bipartite ecological network analysis revealed the intricate relationships between chigger and host species-positive and negative correlations existed among some species of dominant and vector chiggers.

Infestation and distribution of chiggers on the Anderson's white-bellied rats in southwest China.

As a group of ectoparasites, chiggers (larvae of chigger mites) are the exclusive vector of scrub typhus (tsutsugamushi disease). Rodents are the most important hosts of chiggers. The Anderson's niviventer rat, Niviventer andersoni, is an endemic species of rodent in China. However, few studies have involved this endemic rodent species and its ectoparasites including chiggers. According to the field investigation in five provincial regions of southwest China between 2001 and 2019, this paper retrospectively analysed the infestation and distribution of chiggers on the body surface of N. andersoni in southwest China for the first time. From 77 Anderson's niviventer rats captured, a total of 527 chiggers were collected and they were identified as 39 species and nine genera in two subfamilies of family Trombiculidae. Of 39 chigger species identified, Leptotrombidium deliense and L. scutellare are the most important vectors of scrub typhus in China. The overall infestation indexes were PM = 29.87%, MA = 6.84 and MI = 22.91, and the indexes of chigger mite community were Mf = 39, H' = 2.60, E = 0.71 and D = 0.12. The dominant chigger species are L. wenense, L. xiaguanense and L. fujianense with a total Cr = 51.04%, among which L. wenense is one of the six main vectors of scrub typhus in China. The dominant chigger species are of aggregated distribution among different individuals of the rats.

Disease vector occurrence and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019.

Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019. Chiggers were identified under the microscope, and infestation indices were calculated. The Preston's log-normal model was used to fit the curve of species abundance distribution. A total of 6,557 chiggers were collected in 136 of 342 N. fulvescens rats, showing high overall infestation indices (prevalence=39.8%, mean abundance=19.2, mean intensity=48.2) and high species diversity (S=100, H'=3.0). Leptotrombidium cangjiangense, Neotrombicula japonica, and Ascoschoengastia sifanga were the three dominant chigger species (constituent ratio=42.9%; 2,736/6,384) and exhibited an aggregated distribution among different rat individuals. We identified 100 chigger species, with 3 of them (Leptotrombidium scutellare, Leptotrombidium wenense, and Leptotrombidium deliense) as the main vectors of scrub typhus in China and nine species as potential vectors of this disease. Disease vector occurrence on N. fulvescens may increase the risk of spreading scrub typhus from rats to humans. Chigger infestation on N. fulvescens varied significantly in different environments. The species abundance distribution showed a log-normal distribution pattern. The estimated number of chigger species on N. fulvescens was 126 species.

Comparison of Chiggers (Acari: Trombiculidae, Leeuwenhoekiidae) on Two Sibling Mouse Species, Apodemus draco and A. ilex (Rodentia: Muridae), in Southwest China.

Chigger mites (Acari) are common ectoparasites on rodents, and they are the exclusive vector of scrub typhus. South China field mouse (Apodemus draco) and Lantsang field mouse (A. ilex) are two sibling rodent species. Based on field investigations in southwest China (2001-2015), this paper compared the infestation of these two mouse species with chiggers. Of 42 chigger species identified from two mouse species, 36 were found on A. draco, 11 on A. ilex and 5 common species on both mice. Jaccard similarity index (J = 0.12, J < 0.25) showed a very different species composition of chiggers on two mouse species, and some parameters of the chigger community were also different. The overall mean intensity of chiggers on A. draco (MI = 4.26) was higher than that on A. ilex (MI = 3.91, p < 0.05). The dominant chigger species on A. draco were Trombiculindus yunnanus, Leptotrombidium scutellare (a major vector species in China) and L. sinicum with a total constituent ratio Cr = 42.9% (106/247). Leptorombidium sinicum and L. scutellare independently occurred on A. draco with an association coefficient V = 0.09 (V ≈ 0). The dominant chigger species on A. ilex were L. rusticum, L. densipunctatum and L. gongshanense, with a total Cr = 58.14% (25/43). Leptorombidium rusticum and L. densipunctatum on A. ilex had a slight positive association (V = 0.49, 0.5 < V < 1). All dominant chigger species were unevenly distributed among different individuals of two mouse species. Chigger infestation showed sex bias on different sexes of two mouse species. The species abundance of the chigger community on A. draco was revealed as a log-normal distribution pattern.

Potential distribution of Leptotrombidium scutellare in Yunnan and Sichuan Provinces, China, and its association with mite-borne disease transmission.

BACKGROUND: Leptotrombidium scutellare is one of the six main vectors of scrub typhus in China and is a putative vector of hemorrhagic fever with renal syndrome (HFRS). This mite constitutes a large portion of the chigger mite community in southwest China. Although empirical data on its distribution are available for several investigated sites, knowledge of the species' association with human well-being and involvement in the prevalence of mite-borne diseases remains scarce. METHODS: Occurrence data on the chigger mite were obtained from 21 years (2001-2021) of field sampling. Using boosted regression tree (BRT) ecological models based on climate, land cover and elevation variables, we predicted the environmental suitability for L. scutellare in Yunnan and Sichuan Provinces. The potential distribution range and shifts in the study area for near-current and future scenarios were mapped and the scale of L. scutellare interacting with human activities was evaluated. We tested the explanatory power of the occurrence probability of L. scutellare on incidences of mite-borne diseases. RESULTS: Elevation and climate factors were the most important factors contributing to the prediction of the occurrence pattern of L. scutellare. The most suitable habitats for this mite species were mainly concentrated around high-elevation areas, with predictions for the future showing a trend towards a reduction. Human activity was negatively correlated with the environmental suitability of L. scutellare. The occurrence probability of L. scutellare in Yunnan Province had a strong explanatory power on the epidemic pattern of HFRS but not scrub typhus. CONCLUSIONS: Our results emphasize the exposure risks introduced by L. scutellare in the high-elevation areas of southwest China. Climate change may lead to a range contraction of this species towards areas of higher elevation and lessen the associated exposure risk. A comprehensive understanding of the transmission risk requires more surveillance efforts.

Infestation of Oriental House Rat (Rattus tanezumi) with Chigger Mites Varies along Environmental Gradients across Five Provincial Regions of Southwest China.

Chigger mites are the exclusive vector of scrub typhus. Based on field investigations of 91 survey sites in 5 provincial regions of Southwest China, this paper reported variations of chigger infestation on the oriental house rat (Rattus tanezumi) along various environmental gradients. A total of 149 chigger species were identified from 2919 R. tanezumi in the 5 provincial regions, and Leptotrombidium deliense (a major vector of scrub typhus in China) was the first dominant chigger species, followed by Ascoschoengastia indica and Walchia ewingi. Rattus tanezumi had a stable overall prevalence (PM = 21.10%), mean abundance (MA = 7.01), and mean intensity (MI = 33.20) of chiggers with the same dominant mites in the whole Southwest China in comparison with a previous report in Yunnan Province, but chigger infestations on R. tanezumi varied along different environmental gradients. Rattus tanezumi in mountainous landscape had a higher infestation load of chiggers with higher species diversity than in flatland landscape. The infestation was higher at lower altitudes and latitudes. A high intensity of vegetation coverage was associated with high infestations. The results reflect the environmental heterogeneity of chiggers on the same host species. Warm climate and high relative humidity are beneficial to chigger infestation on R. tanezumi.

Preliminary Study on Species Diversity and Community Characteristics of Gamasid Mites on Small Mammals in Three Parallel Rivers Area of China.

(1) Background: Gamasid mites are a large group of arthropods, and some of them are of medical importance. Besides directly biting humans and causing dermatitis, some gamasid mites are the vector of rickettsialpox and potential vector of hemorrhagic fever with renal syndrome (HFRS). The Three Parallel Rivers Area of China is one of the hotspots of biodiversity research in the world, with complicated topographic landforms, different types of vegetation, special elevation gradients and high biodiversity. (2) Methods: Species richness (S): the Shannon-Wiener diversity index (H), Simpson dominance index (D) and Pielou evenness index (E) were used to analyze the basic community structure. The ß diversity (Cody index) was used to reflect the diversity difference between any two adjacent elevation gradients. The method based on Preston's lognormal model for species abundance distribution was used to estimate the total number of gamasid mite species. (3) Results: A total of 3830 small mammal hosts captured from the nine survey sites were identified as 44 species, 27 genera and nine families in five orders. Apodemus chevrieri, Eothenomys miletus and A. draco were the dominant host species with a total constituent ratio Cr = 52.037%. From the body surface of the hosts, 26,048 gamasid mites were collected and identified as 10 families, 21 genera and 82 species (excluding 847 unidentified specimens) with high species richness (S = 82) and diversity (H = 2.33). The three dominant mite species were Dipolaelaps anourosorecis, Laelaps nuttalli and L. echidninus, with a total Cr = 64.46% (16,791/26,048). There are significant differences in the species composition, species diversity and dominant species of gamasid mites on different hosts. The species diversity of the mite community fluctuated greatly in different elevation gradients. The highest peaks of species richness and ß diversity appeared at altitudes of 3000-3500 m (S = 42) and 1500-2000 m (ß = 17.5), respectively. The species abundance distribution of the mites was successfully fitted by Preston's lognormal model with S^(R)=19e-[0.22(R-0)]2 (α = 0.22, R2 = 0.9879). Based on fitting the theoretical curve by Preston's model, the total number of gamasid mite species was estimated to be 153 species. (4) Conclusions: Gamasid mites on small mammals are abundant with complex community structures and high species diversity in the Three Parallel Rivers Area of China. There is an apparent community heterogeneity of the mites on different hosts and in different environments.

Analysis on infestation and related ecology of chigger mites on large Chinese voles (Eothenomys miletus) in five provincial regions of Southwest China.

Based on a long-term field investigation in the five provincial regions of Southwest China between 2001 and 2019, the present paper studied the infestation and related ecology of chigger mites (chiggers) on the large Chinese vole (Eothenomys miletus), an endemic and dominant rodent species in the regions. A total of 52331 chiggers were collected from 2661 voles, and 52261 mites were identified as 185 species and 13 genera in the family Trombiculidae with very high species diversity. The identified 185 chigger species on E. miletus (a single rodent species) even exceeded those recorded in some countries. The overall infestation prevalence (P m  = 53.96%), mean abundance (MA = 19.64) and mean intensity (MI = 36.39) on E. miletus were much higher than those on some other rodent species in the same regions. Although the species composition showed a moderate similarity (J = 0.63) between male and female hosts (E. miletus), the infestation indices (P m  = 56.25%, MA = 21.67) of chiggers on male hosts were higher than those on the females (P m  = 51.23%, MA = 17.09) (P < 0.05). Two dominant chigger species, Leptotrombidium scutellare (C r  = 19.17%) and L. sinicum (C r  = 11.06%), showed an aggregated distribution pattern among different individuals of their host E. miletus, and a relatively high degree of positive association existed between the two dominant chigger species with PCC = 0.57, DI = 0.60 and OI = 0.62 (x 2  = 857.46, P < 0.001). Leptotrombidium densipunctatum, Walchia koi, Helenicula hsui, L. scutellare and W. ewingi showed a high degree of environmental adaptability to their environments with high niche breadths. The theoretical curve of the species abundance distribution of chigger community on E. miletus was successfully fitted with Preston's lognormal distribution model. Based on the theoretical curve fitting, the expected total number of chigger species on E. miletus was roughly estimated to be 223 species, and 38 chigger species were probably missed in the sampling investigation.

Infestation of chigger mites on Chinese mole shrew, Anourosorex squamipes, in Southwest China and ecological analysis.

The Chinese mole shrew, Anourosorex squamipes Milne-Edwards, 1872, is a common species of insectivorous mammal in Southwest China. Based on field investigations between 2001 and 2019, the present study reports the infestation of chiggers (larvae of chigger mites) on the shrew in Southwest China and certain ecology parameters for the first time. A total of 3169 chiggers were collected from 1694 A. squamipes and they were identified into 72 species and 10 genera in the family Trombiculidae. The overall infestation prevalence (Pm), mean abundance (MA) and mean intensity (MI) of A. squamipes with chiggers reached 11.1%, 1.87 and 16.86, respectively. The species diversity, species composition and infestation of chiggers on A. squamipes fluctuated in different environments (latitudes, altitudes, habitats and landscapes) and on different sexes and ages of the shrew hosts with high heterogeneity and low species similarity. In the established linear regression equation (M* = 0.173 + 1.054 M) for dominant mite Leptotrombidium densipunctatum, both the α and ß values (α = 0.173, ß = 1.054) exceeded the boundary values (F = 4.67, p < 0.05), and therefore the spatial distribution pattern of this mite was determined as an aggregated distribution among different individuals of shrew hosts. The species abundance distribution of the chigger community on A. squamipes conformed to the lognormal distribution, and its curve showed a gradually descending tendency from the rare mite species to the dominant mite species. The curve tendency of species-sample relationship implies that more species of chiggers would be found if the host samples infinitely keep increasing.

Title: Infestation de la musaraigne Anourosorex squamipes par les acariens dans le sud-ouest de la Chine et analyse écologique. Abstract: La musaraigne Anourosorex squamipes Milne-Edwards, 1872 est une espèce commune de mammifère insectivore dans le sud-ouest de la Chine. Sur la base d'enquêtes de terrain entre 2001 et 2019, la présente étude signale pour la première fois l'infestation et certains paramètres écologiques des acariens larvaires sur cette musaraigne dans le sud-ouest de la Chine. Un total de 3169 acariens ont été collectés sur 1694 A. squamipes et ils ont été identifiés en 72 espèces et 10 genres de la famille des Trombiculidae. La prévalence globale de l'infestation (Pm), l'abondance moyenne (MA) et l'intensité moyenne (MI) des acariens sur A. squamipes ont atteint respectivement 11,1 %, 1,87 et 16,86. La diversité des espèces, la composition des espèces et l'infestation des acariens sur A. squamipes ont fluctué selon différents environnements (latitudes, altitudes, habitats et paysages) et selon le sexe et l'âge des hôtes avec une forte hétérogénéité et une faible similitude entre espèces. Dans l'équation de régression linéaire établie (M* = 0,173 + 1054 M) pour l'acarien dominant Leptotrombidium densipunctatum, les valeurs α et ß (α = 0,173, ß = 1,054) dépassaient les valeurs limites (F = 4,67, p < 0,05), et par conséquent, le modèle de distribution spatiale a été déterminé comme une distribution agrégée entre différents individus d'hôtes. La distribution de l'abondance des espèces de la communauté d'acariens sur A. squamipes se conformait à la distribution log-normale et la courbe a montré une tendance progressivement descendante des espèces d'acariens rares à l'espèce d'acarien dominante. La tendance de la courbe de la relation espèce-échantillon implique que davantage d'espèces d'acariens seraient trouvées si l'échantillonnage des hôtes continuaient à augmenter à l'infini.

Infestation and Seasonal Fluctuation of Gamasid Mites (Parasitiformes: Gamasida) on Indochinese Forest Rat, Rattus andamanensis (Rodentia: Muridae) in Southern Yunnan of China.

A 12-month consecutive investigation was made at Jingha village in southern Yunnan of southwest China from April 2016 to March 2017. A total of 2053 Indochinese forest rats (Rattus andamanensis Blyth, 1860) were captured and examined, which account for 84.69% (2053/2424) of all the animal hosts (rodents and other small mammals) at the investigation site. And 39.82% (13,531/33,980) of gamasid mites were identified from the body surface of R. andamanensis and they belong to 41 species, 10 genera, 3 subfamilies and 2 families. Of the 41 species of gamasid mites identified from R. andamanensis, Laelaps nuttalli Hirst, 1915 and Laelaps echidninus Berlese, 1887 were the most dominant with 70.63% and 20.67% of constituent ratios respectively. In monthly fluctuations of all the gamasid mites on R. andamanensis, the constituent ratio (Cr) and overall infestation mean abundance (MA) of the mites in 12 months showed two obvious peaks in January (winter season) and June (summer season). However, the two dominant mite species, L. nuttalli and L. echidninus, showed different patterns of seasonal fluctuations. Laelaps nuttalli occurred throughout the year, and its Cr and MA showed two prominent peaks in winter season (December and January) and summer season (June), which belongs to the summer-winter type of seasonal fluctuation. Laelaps echidninus also occurred on R. andamanensis throughout the year, but its Cr and MA showed only one peak in winter season (December and January), which belongs to the winter type of seasonal fluctuation. A negative correlation existed between two climatic factors (temperature and rainfall) and the infestations (Cr, prevalence PM and MA) of two dominant mite species (L. nuttalli and L. echidninus) on R. andamanensis (p < 0.05). Temperature and rainfall are considered to be two key factors that influence the seasonal fluctuations of the mites on the studied rat species.

Phylogenetic and morphological significance of an overlooked flying squirrel (Pteromyini, Rodentia) from the eastern Himalayas with the description of a new genus.

The flying squirrels (Pteromyini, Rodentia) are the most diverse and widely distributed group of gliding mammals. Taxonomic boundaries and relationships within flying squirrels remain an area of active research in mammalogy. The discovery of new specimens of Pteromys ( Hylopetes) leonardi Thomas, 1921 previously considered a synonym of Hylopetes alboniger, in Yunnan Province, China allowed a morphological and genetic reassessment of the status of this taxon. Phylogenetic reconstruction was implemented using sequences of two mitochondrial (12S ribosomal DNA and 16S ribosomal DNA) and one nuclear (interphotoreceptor retinoid-binding protein) gene fragments. Morphological assessments involved examinations of features preserved on skins, skulls, and penises of museum specimens, supplemented with principal component analysis of craniometric data. Together these assessments revealed that this taxon should be recognized not only as a distinct species, and should also be placed within a new genus, described here as Priapomys.

Isolated alpine habitats reveal disparate ecological drivers of taxonomic and functional beta-diversity of small mammal assemblages.

The interpretation of patterns of biodiversity requires the disentanglement of geographical and environmental variables. Disjunct alpine communities are geographically isolated from one another but experience similar environmental impacts. Isolated homogenous habitats may promote speciation but constrain functional trait variation. In this study, we examined the hypothesis that dispersal limitation promotes taxonomic divergence, whereas habitat similarity in alpine mountains leads to functional convergence. We performed standardized field investigation to sample non-volant small mammals from 18 prominent alpine sites in the Three Parallel Rivers area. We estimated indices quantifying taxonomic and functional alpha- and beta-diversity, as well as beta-diversity components. We then assessed the respective importance of geographical and environmental predictors in explaining taxonomic and functional compositions. No evidence was found to show that species were more functionally similar than expected in local assemblages. However, the taxonomic turnover components were higher than functional ones (0.471±0.230 vs. 0.243±0.215), with nestedness components showing the opposite pattern (0.063±0.054 vs. 0.269±0.225). This indicated that differences in taxonomic compositions between sites occurred from replacement of functionally similar species. Geographical barriers were the key factor influencing both taxonomic total dissimilarity and turnover components, whereas functional beta-diversity was primarily explained by climatic factors such as minimum temperature of the coldest month. Our findings provide empirical evidence that taxonomic and functional diversity patterns can be independently driven by different ecological processes. Our results point to the importance of clarifying different components of beta-diversity to understand the underlying mechanisms of community assembly. These results also shed light on the assembly rules and ecological processes of terrestrial mammal communities in extreme environments.

Massive migration promotes the early spread of COVID-19 in China: a study based on a scale-free network.

BACKGROUND: The coronavirus disease 2019 (COVID-19) epidemic met coincidentally with massive migration before Lunar New Year in China in early 2020. This study is to investigate the relationship between the massive migration and the coronavirus disease 2019 (COVID-19) epidemic in China. METHODS: The epidemic data between January 25th and February 15th and migration data between Jan 1st and Jan 24th were collected from the official websites. Using the R package WGCNA, we established a scale-free network of the selected cities. Correlation analysis was applied to describe the correlation between the Spring Migration and COVID-19 epidemic. RESULTS: The epidemic seriousness in Hubei (except the city of Wuhan) was closely correlated with the migration from Wuhan between January 10 and January 24, 2020. The epidemic seriousness in the other provinces, municipalities and autonomous regions was largely affected by the immigration from Wuhan. By establishing a scale-free network of the regions, we divided the regions into two modules. The regions in the brown module consisted of three municipalities, nine provincial capitals and other 12 cities. The COVID-19 epidemics in these regions were more likely to be aggravated by migration. CONCLUSIONS: The migration from Wuhan could partly explain the epidemic seriousness in Hubei Province and other regions. The scale-free network we have established can better evaluate the epidemic. Three municipalities (Beijing, Shanghai and Tianjin), eight provincial capitals (including Nanjing, Changsha et al.) and 12 other cities (including Qingdao, Zhongshan, Shenzhen et al.) were hub cities in the spread of COVID-19 in China.

Inhibition of heparanase protects against pancreatic beta cell death in streptozotocin-induced diabetic mice via reducing intra-islet inflammatory cell infiltration.

BACKGROUND AND PURPOSE: Intra-islet heparan sulfate (HS) plays an important role in the maintenance of pancreatic islet function. The aim of this study was to investigate the effect mechanism of HS loss on the functioning of islets in diabetic mice. EXPERIMENTAL APPROACH: The hypoglycaemic effect of a heparanase inhibitor, OGT2115, was tested in a streptozotocin-induced diabetic mouse model. The islets in pancreatic sections were also stained to reveal their morphology. An insulinoma cell line (MIN6) and primary isolated murine islets were used to investigate the effect of OGT2115 in vitro. KEY RESULTS: Intra-islet HS was clearly lost in streptozotocin-induced diabetic mice due to the increased heparanase expression in damaged islets. OGT2115 prevented intra-islet HS loss and improved the glucose profile and insulin secretion in streptozotocin-treated mice. The apoptosis of pancreatic beta cells and the infiltration of mononuclear macrophages, CD4- and CD8-positive T-cells in islets was reduced by OGT2115 in streptozotocin-treated mice, but OGT2115 did not alter the direct streptozotocin-induced damage in vitro. The expression of heparanase was increased in high glucose-treated isolated islets but not in response to direct streptozotocin stimulation. Further experiments showed that high glucose stimuli could decreased expression of PPARγ in cultured islets, thereby relieving the PPARγ-induced inhibition of heparanase gene expression. CONCLUSION AND IMPLICATIONS: Hyperglycaemia could cause intra-islet HS loss by elevating the expression of heparanase, thereby aggravating inflammatory cell infiltration and islet damage. Inhibition of heparanase might provide benefit for pancreatic beta cell protection in Type 1 diabetes.

Relative Abundance of a Vector of Scrub Typhus, Leptotrombidium sialkotense, in Southern Yunnan Province, China.

The chigger mite Leptotrombidium sialkotense is one of the 6 main vectors of scrub typhus in China. Before present study, L. sialkotense was found in some parts of Hunan province, China with a narrow geographical distribution. During field investigation 2016-2017, we found L. sialkotense in Jingha, southern Yunnan, China. Of 15 small mammal host species, L. sialkotense were collected from 6 species of the hosts. Rattus brunneusculus was a dominant host of L. sialkotense, from which 98.3% of the mites were collected. The chigger mite showed a relatively high infestation prevalence (PM=11.7%) and mean abundance (MA=0.5) in comparison with the rest 5 host species. These results reveal a certain host specificity of L. sialkotense to a rat R. brunneusculus. The mite L. sialkotense showed an aggregated distribution on the host (P<0.05). A positive correlation observed between L. sialkotense and the body length of hosts. There was a positive interspecific association between L. sialkotense and 2 other dominant vectors, L. deliense and L. scutellare.

Discovery and description of a mysterious Asian flying squirrel (Rodentia, Sciuridae, Biswamoyopterus) from Mount Gaoligong, southwest China.

The flying squirrels of the tribe Pteromyini (Family Sciuridae) currently include 15 genera of which the genus Biswamoyopterus comprises two recognized species, B.biswasi Saha, 1981 and B.laoensis Sanamxay et al., 2013. These two species were each described from only one specimen that are separated from each other by 1,250 kilometres in southern Asia, where they occur in northeast India and central Lao PDR respectively. In 2017 and 2018, two specimens of Biswamoyopterus were discovered from Mount Gaoligong, west Yunnan province, southwest China (between the type locality of the two recognized species). This study aimed to evaluate the taxonomic status of these two newly acquired specimens of Biswamoyopterus by comparing their morphology with the two described species of the genus. The results of this study showed that the specimens from Yunnan province (China) differed from both B.laoensis and B.biswasi in both pelage colour and craniology, and should be recognised as a distinct species, B.gaoligongensis sp. nov., which is formally described here. This study contributes to the understanding of the flying squirrels of southern Asia and identifies an additional species that appears to be endemic to southwest China; however, more research is required to provide details of its ecology, distribution, and conservation status.

Species Abundance Distribution of Ectoparasites on Norway Rats (Rattus norvegicus) from a Localized Area in Southwest China.

BACKGROUND: The species of ectoparasites that live on a specific host in a geographical region form an ectoparasite community. Species abundance distributions describe the number of individuals observed for each different species that is encountered within a community. Based on properties of the species abundance distribution, the expected total number of species present in the community can be estimated. METHODS: Preston's lognormal distribution model was used to fit the expected species abundance distribution curve. Using the expected species abundance distribution curve, we estimated the total number of expected parasite species present and the amount of species that were likely missed by our sampling in the field. RESULTS: In total, 8040 ectoparasites (fleas, sucking lice, gamasid mites and chigger mites) were collected from 431 Norway rats (Rattus norvegicus) from a localized area in southwest China. These ectoparasites were identified to be 47 species from 26 genera in 10 families. The majority of ectoparasite species were chigger mites (family Trombiculidae) while the majority of individuals were sucking lice in the family Polyplacidae. The expected species abundance distribution curve demonstrated the classic pattern that the majority of ectoparasite species were rare and that there were a few common species. The total expected number of ectoparasite species on R. norvegicus was estimated to be 85 species, and 38 species were likely missed by our sampling in the field. CONCLUSIONS: Norway rats harbor a large suite of ectoparasites. Future field investigations should sample large numbers of host individuals to assess ectoparasite populations.

Species diversity of ectoparasitic chigger mites (Acari: Prostigmata) on small mammals in Yunnan Province, China.

Chigger mites are a large group of arthropods and the larvae of mites are ectoparasites. Some species of ectoparasitic mites (larvae) can be the transmitting vectors of tsutsugamushi disease (scrub typhus). Yunnan Province is located in the southwest of China with complicated topographic landform and high biodiversity, where there are five zoogeographical subregions. Rodents and some other small mammals were trapped and examined for ectoparasitic chigger mites in 29 investigation sites in Yunnan during 2001-2013. From 13,760 individuals and 76 species of small mammal hosts, we collected 274 species of mites, which were identified as comprising 26 genera in two families. The species diversity of chigger mites (274 species) in the present study were not only much higher than that from other provinces of China but also largely exceeded that recorded from other regions and countries in the world. Of the five zoogeographical subregions, both the species diversity and Shannon-Weiner's diversity of mites were the highest in subregion II (southern subregion of Hengduan Mountains) with middle altitudes and middle latitude. Both the species diversity of mites and Shannon-Wiener diversity index showed a parabolic tendency from the low altitude (<500 m) to the high altitude (>3500 m) along the vertical gradients with the peak occurring in the middle-altitude regions (2000-2500 m). Of four dominant hosts, the species richness of mites was highest on Eothenomys miletus (S = 165) and Shannon-Wiener diversity index was highest on Rattus norvegicus (H = 3.13). Along latitude gradients, species richness of chigger mites increased first and then decreased, peaking at 25° to 26° N with 193 mite species. The geographical location, complex topography, and landscape with diverse small mammal hosts in Yunnan Province have contributed to the extremely high species diversity of mites in the province. The large sampling size of small mammal hosts in a wide geographical scope within a long time span also made it possible to have collected so many species of chigger mites.

An updated distribution and hosts: trombiculid mites (Acari: Trombidiformes) associated with small mammals in Yunnan Province, southwest China.

Trombiculid mites (or chigger mites) are a large group of arthropods, and some of these species are vectors of Orientia tsutsugamushi, the causative agent of tsutsugamushi disease (scrub typhus). Yunnan Province is situated in the southwest of China, and its complicated topography, special altitude gradients, and high biodiversity have aroused the interest of many scientists to study the fauna and species diversity of plants and animals. To replenish our former faunal study, this paper listed all the scientific names of trombiculid mites in Yunnan Province, together with their hosts and collection sites (geographical distribution). A total of 120,138 individuals of trombiculid mites were collected from the body surface of 13,760 small mammal hosts (89.06 % of them are rodents) in 29 collection sites (counties) of Yunnan Province from 2001 to 2013. The 120,138 mites were identified as comprising 2 families (Trombiculidae and Leeuwenhoekiidae), 26 genera, and 274 species. The genus Leptotrombidium had the most abundant species (109 species) of 26 genera. Of the six main vectors of scrub typhus in China, five of them were found in Yunnan. Of the 274 chigger mite species, 23 were determined as the newly recorded species (new records), which were found in Yunnan Province for the first time. The identified 274 species of trombiculid mites in the present paper are much more than those from other provinces in China and even largely exceeded the species of trombiculid mites recorded from some other regions and countries in the world. Based on the formula of Chao 1, the total number of chigger mite species in Yunnan was approximately estimated to be 346 species, and about 72 species might have been missed in our sampling process.