Biodiversity And Geographic Distribution Of Cicadas Occurring Along Eastern Margin Of Qinghai-Tibet Plateau

Areas along the eastern margin of the Qinghai-Tibet Plateau(QTP),the transitional regions of the lateral expansion of QTP,are the transitional zones between the Palaearctic and Oriental Regions.These areas contain diverse geographical environment and climate conditions,and are one of the hot spots in the study of global biodiversity.Insects of the family Cicadidae(Insecta: Hemiptera)live underground for a long time,with short adult stage,large body size,weak flight ability and difficulty in dispersal.Therefore,cicadas are suitable for biogeographical and biodiversity studies.However,our understanding of the biodiversity and fauna of cicada in areas along the eastern margin of QTP are extremely limited.In this study,we collected specimens,distribution information and literature records of Cicadidae in eastern margin of QTP,and analyzed the fauna of cicada from the eastern margin of the QTP,described the newly recorded species.The species and faunal types of Cicadidae in the eastern margin of QTP were clarified,based on which the distribution areas of insects occurring along the eastern margin of QTP were repartitioned.The climate factors affecting the distribution of cicadas in the eastern margin of QTP were analyzed.The results show that 100 species belonging to 46 genera and 3 subfamilies of Cicadidae occur in areas along the eastern margin of QTP,accounting for 60.5% and 28.8%of the known genera and species in China,respectively.Most of them are Oriental species(73 species,73.0%),which are followed by species occurring in both the Palearctic and Oriental Region(21 species,21.0%),and then followed by the endemic species(19 species,19.0%).The endemic species mainly distribute in the southern region along the eastern margin of QTP.Mata kama、 Mata meghalayana、Manna tenui and Hyalessa expansa are new recorded in China.Mata kama and Mata meghalayana are only distributed in the eastern margin of the QTP.The 10 subregions can be divided into two groups,with a boundary to be the Qinling Mountains and mountainous areas in southern Gansu Province.The northern subregions belonging to the Palearctic Region comprise the Loess Plateau transition zone(MX+HB)and the northern Tibet transition zone(QZ),which have a low species diversity,and the species occurring there are mainly small-sized cicadas of the subfamily Cicadettinae.The southern subregions belonging to the Oriental Region include the transition zone of western Qinling Mountains(HZⅠ+XNⅠ),the transition zone of western Sichuan Basin and northern Yunnan(HZⅡ+XNⅣ),the pleateau–mountain transition zone of the Hengduan Mountains(XNⅡ+XNⅢ),and the mountainous transition zone of western Yunnan(HN).The species diversity of subregion increases gradually from north to south,with western Sichuan Basin and southern Hengduan Mountains being the biodiversity centers.In regard to the subregions in the southern section,(XNI+HZI)clustered with(HZII+XNⅣ)first,and then clustered with(XNⅡ+XNⅢ)and HN subsequently.The results indicate that the subregion located at weastern Yunnan(HN)and the pleateau–mountain transition zone between southeastern QTP and the Hengduan Mountains(XNⅡ+XNⅢ)are relatively unique.The results of climate factor analysis showed that temperature and humidity were closely related to the distribution of cicadas in the eastern margin of QTP.Four climatic factors,namely,Precipitation variation coefficient,Precipitation of the driest quarter,Isothermality and Monthly mean diurnal temperature range,had a high degree of influence on distribution of cicadas along longitude(X)in the eastern margin of QTP;Precipitation variation coefficient,Precipitation variation coefficient,Range of annual temperature and Monthly mean diurnal temperature range,had great influence on the distribution of cicadas along latitude(Y).The key climatic factors which affecting the geographical distribution of cicadas in the eastern margin of QTP are Range of annual temperature and Isothermality.This study clarified the influence of geographical conditions,climate factors on the diversity and distribution pattern of cicadas in the QTP,and repartitioned the fauna of the QTP by cicadas,and the new records of Cicadidae in the eastern margin of QTP were described.The results expand our knowledge of the cicada fauna in China and are informative for research of biogeography and the mechanisms of biodiversity formation,maintenance and loss in areas along the eastern margin of QTP.