关键词: 直翅目, 蝗总科, 蝗虫, 分类, 形态, 雄性外生殖器, 主成分分析

Abstract: 【Aim】To clarify the key characteristics and indexes of male external genitalia of grasshoppers for accurately identifying the grasshoppers in grasslands of the Jiuquan Area of Gansu, northwestern China. 【Methods】 We dissected and compared the structure of male external genitalia of adults of 12 species of grasshoppers collected from grasslands of Jiuquan, Gansu, which belong to seven genera of three families (Oxya chinensis and O. adentata of Oxya of Catantopidae; Oedaleus manjius and O. infernalis of Oedaleus, Epacromius coerulipes and E. tergestinus tergestinus of Epacromius, Sphingonotus
ningsianus and S. yenchihensis of Sphingonotus, Compsorhipis davidiana of Compsorhipis of Oedipodidae; Chorthippus brunneus huabeiensis and C. albonemus of Chorthippus, and Euchorthippus unicolor of Euchorthippus of Arcypteridae). And we analyzed eight indexes of male external genitalia by principal component analysis. 【Results】The epiphalli of the genus Oxya in the family Catantopidae are narrow bridge-shaped and have no ancorae, and the zygomata of phallic complex are very wide, while the epiphalli of the other 10 species of grasshoppers were wide bridge-shaped and have ancorae, and the zygomata of phallic complex are narrow. The basal vaves of penis of phallic complex in Oedipodidae are wide and round, but in Arcypteridae, they are hook-shaped. About the shape of lophi, it varies significantly among different genera. In addition, the principal component analysis of eight indexes of male externul genitalia of 12 species of grasshoppers showed that there were two principal components with the eigenvalues greater than 1.00, which were the 1st principal component and the 2nd principal component, respectively, with a total contribution rate up to 78.27%. The main components of the 1st principal component included the outer distance of ancorae, the outer distance of posterior projection, the inner distance of ancorae, the height of ancorae, the distance between the two ancoraes, and the width of bridge, and the main component of the 2nd principal component was the length-to-width ratio of phallic complex. 【Conclusion】 The male external genitalia of grasshoppers possess significant differences among families, genera and species, which can be used to distinguish the 12 species of grasshoppers in Jiuquan Area. The relative position of ancorae, the outer distance posterior projection, the width of bridge and the size of the phallic complex in the male external genitalia are principal indexes when distinguishing these 12 species of grasshoppers.

Key words: Orthoptera, Acridoidea, grasshopper, taxonomy, morphology, male external genitalia, principal component analysis