Studies on the composition of Acridoidea fauna and its regional distribution in Nei Mongol (Inner Mongolia) autonomous region.

This paper deals with the faunal charateristics of the Acridoidea and its regional distribution in Nei Mongol (Inner Mongolia) Autonomous Region. The analysis is based on our own data and 34613 specimens of Acridoidea collected from more than 90 localities investigated during 1983-1989 (Fig.l.). And 95 species belonging to 5 families, 13 subfamilies and 40 genera are included (Tab.1). Four topics are discussed in this paper, namely: 1. geographical limits researched and its general natural geographical features; 2. composition of the Acridoidea fauna; 3. the rules of regional distribution of the Acridoidea; 4. hypothesis on the origin and evolution of the Acridoidea fauna in Nei Mongol (Inner Mongolia) Autonomous Region.Nei Mongol is situated in middle-eastern Asia, at N37°25/-53°21 and E97°29'-125°50', with ah areas of 1.5 million KM2. According to the differences in topography, it ean de divided into three large distinct topographical regions, i.e., the main body of Nei Mongol plateau,the marginal moutains of Nei Mongol plateau as well as the outside marginal plains and plateau (Fig. 1). From the viewpoint of zoogeography, Nei Mongol should belong to the Palaearctic Regien.On the basis of the results of our research, 87.4% of the Acridoidea fauna in Nei Mongol region are Palaearctic species (Tabs. 1,2). Only a part of them are widely-distributed species (10.5%); fundamentally most of the Oriental species can not exist in this region (1.0%). However, the endemic species has a larger ratio to the total (24.2%XTab.2). In this paper four sub-grades under Palaearctic species in Nei Mongol are recorded as follows (Tab.1): 1. Pan-Palaearctic species, such as Fillchnerella beidi, Oxya adentata, and Parapleurus alliaceus alliaceus ect. with total of 30 species (31.6%) belonging to 17 genera and 4 families; 2.Sibiro-Mongolian species are the most dominant components in the Acridoidea fauna of Nei Mongol region, such as Paimnoa primnoa, Eirenephillus longipennis, and Oedaleus decorus asiaticus etc, with a total of 39 species (41.1%) belonging to 20 genera and 4 families; 3. Alashan-Mongolian species have been sauggested by authors as a new concept of faunal geo- graphical component in his paper, such as Pseudotmethis alashanicus. P. brachyptcrus. Ps. rubimarginis, Eotmethis holanensis, Sphingonotus obscuratus latissimus, Brytdema kozlovi, Br. nigroptera etc. with a total of 12 species (12.6%) belonging to 5 genera and 2 families. The reasons of the above suggestion are as follows: during the Pliocene Epoch (in Tertiary Period), Qing-Zang Plateau and Alashan Planal to as well as the Holanshan Mountain uplifted, caused by Himalayan mountains-making movement then the influences of seasonal winds blowing from the Indian and Pacific Oceans to Alashan Planalto were resisted so that the modern Alashan Desert formed. In the meanwhile the Acridoidea fauna of the Alashan district were created.The whole region of Nei Mongol is subdivided in this paper into three large distinct topographical regions, with a total of 13 natural districts according to their own ecogeographical features (Tab.3). The distributional rules of Acridoidea among the three large distincr topographical regions as well as 13 natural destricts have been analysed and some of the rules are given follow (Tab.3): (1) Species that can distributed extensively in all the three large topographical regions and the 13 subordinate natural districts have been known, such as Caltiptamus abbreviatus, Chorthippus (G.) brynneus huabeiensis, Epacromius coerulipes, Myrmeleotettix palpalis, and Oedaleus dccorus asiaticus, a total of 5 species (5.3%) belonging to 5 genera and 1 family. (2) Species that are distributed in the three topographical regions but not in all of the 13natural districts, such as Rhinotmethis hummeli, Epacromius tergestinus extimus, Sphingonotusmongolicus, etc. (3) Species that are distributed only in the main body of Nei Mongol plateau ,such as Filchnerella beiki, Mecostethus grossus, Compsorhipis bryodemoides etc. a total of 14 species (14.7%) belonging to 13 gen