Morphological Variabilityand Phylogeography Of The Cicada Hyalessa Maculaticollis (Hemiptera:Cicadidae)

The cicada Hyalessa maculaticollis is widely distributed in East Asia,and is noted for its great morphological variability.The differentiation of this species and its allies has been a long-standing controversy.The morphological variations,genetic diversity,population structure,phylogeographic relationships and demographic history of various populations of this species were investigated based on morphological observation and analyses of mitochondrial DNA and nuclear DNA.The main results are as follows:Morphological observations reveal that abundant morphological variations mainly occur on the mesonotum,male opercula and aedeagus of H.maculaticollis,which are consistent with the high levels of genetic divergence.The variations mainly happened in populations occurring in the regions north to Qinling Mountains and East China.The results of phylogenetic,network and AMOVA indicate that the populations of H.maculaticollis distributed in East Asia are significantly structured phylogeographically,which comprise two major lineages,i.e.,China and Japan.The China mainland populations further differentiated into six haplogroups: Clade A1(occurred in the west of Sichuan Basin),Clade A2(occurred in the east of Sichuan Basin),Clade B1(occurred in East China),Clade B2 and Clade B3(occurred in the north of Qinling Mountains),Clade B4(occurred in the south of Qinling Mountains).The result of divergence time indicates that the climatic oscillation influenced the population differentiation of H.maculaticollis.Qinling Mountains and the mountainous regions around the Sichuan Basin are presumed to be major refugia in glacial periods,and some Ice-Age refugia further north of Qinling Mountains might exist.The complex terrain structure in China also influenced the phylogeographical structure of this species.The East China Sea land bridge became entirely submerged after the glacial periods,and the gene flow of H.maculaticollis populations between the China mainland and Japan could be blocked;Qinling–Daba Mountains,the mountainous regions around the Sichuan Basin and the serious valleys caused by Yangtze River and Yellow River led to the population differentiation in mainland China.Neutrality tests and pairwise mismatch distribution analyses both indicate that a rapid demographic expansion has occurred in populations of Clades B2–B3,which distributed in the north of Qinling Mountains.The high values of haplotype and nucleotide diversity of the populations of Clade B1 which distributed in East China show that the flat terrains with low-altitude hills there are suitable for the survival of H.maculaticollis and allow more gene flow to occur.This study discusses the long-standing controversy about the relationship of H.maculaticollis and the allied H.fuscata based on morphological variation,genetic divergence and the calling song structure.The results indicate that H.fuscata is a junior synonym of H.maculaticollis.