中国栖螽属分类修订

Xixicus is a diverse genus in Meconematini, with 7 subgenera and 64 species recorded in the world and 7 subgenera and 45 species known in China. However, great controversies still exist in the defining characteristics and taxonomic status of subgenera, many species are only recorded for type specimens (only know male or female in some species), male and female specimen are difficult to match and the assignment of some species changes frequently. In the present proposal, a comprehensive revision on Chinese members of Xizicus will be conducted based on a wide-ranging collection of specimens and examination of type materials. DNA barcoding analysis will be performed to explore the evolution and variation of COI gene and the performence of the barcode for species identification in Xizicus, using a 658-base fragment of the 5' end of the mitochondial gene cytochrome C oxidase subunit 1 (COI). Mitochondial ND2 gene and nuclear 28S rDNA D2 gene will be sequenced and combined with COI barcodes to construct the molecular phylogenetic tree of Xixicus. DNA barcoding, molecular phylogeny and morphological analysis are combined to confirm the assignment of problematic species and systematic position of subgenera. The aims of this work are to clarify the taxonomy of Xizicus, to complement the current classification system of the Xizicus from comparative morphological and molecular points of view.

栖螽属是蛩螽族的一个大属，全世界已记录7亚属64种，中国记录7亚属45种。中国栖螽属亚属级阶元界定特征不一致，分类地位存在争议；许多种类仅记录模式标本（有些种仅知雄性或雌性），雌雄难以配对；一些物种归属变动频繁。本项目拟在模式产地系统采集和核对模式标本的基础上，依据前胸背板、翅、腹部末端背板、尾须、下生殖板等形态特征，结合雄性发声器超微结构，系统整理研究栖螽属种类；利用线粒体COI 基因5'端658bp片段对中国栖螽属物种进行DNA条形编码研究；联合使用COI条形码片段、ND2基因及核28S rDNA基因D2区序列构建各亚属之间系统发育关系。结合形态学数据和分子数据，解决物种雌雄配对，修订亚属特征，完善栖螽属现行分类系统，完成对中国栖螽属的修订。

根据我国栖螽属的研究现状和分布特点，对四川、海南、陕西、广西、浙江、河南等省区进行了系统考察，查阅了相关院校和标本馆收藏的模式标本，对栖螽属进行了较系统的研究。（1）建立了栖螽亚属1新种Xizicus (Xizicus) tricercus Feng, Shi & Mao, 2017，东栖螽亚属1个新种Xizicus (Eoxizicus) lobicercus Chen, Mao & Chang, 2019；通过形态比较结和分子数据（COI）对三角铲畸螽Shoveliteratura triangula Shi, Bian & Change, 2011的雌性首次做了补充描述，解决了三角铲畸螽的雌雄匹配问题。（2）对栖螽属物种658 bp的COI-5P条形码序列聚类和遗传距离分析表明COI片段能够准确有效鉴定该属物种，进一步联合COI条形码序列和核基因片段ITS1-5.8S rDNA-ITS2对中国栖螽属物种进行系统发育分析，建树结果均支持将东栖螽亚属提升到属级分类地位。对陕西、河南、湖北等8个地理种群的贺氏东栖螽的COI序列和核ITS1-5.8S rDNA-ITS2进行聚类和遗传距离分析，结果证实贺氏东栖螽存在隐存物种，为其分类修订提供了分子依据。（3）基于线粒体PCGs和rRNAs基因对螽斯科物种进行了系统发育关系重建，螽斯亚科、纺织娘亚科、草螽亚科和蛩螽亚科的单系性在BI和ML树上均得到强烈支持，两种建树结果中格尼剑螽都聚在了栖螽属的分支中，需要增加取样对两个属系统发育关系进一步研究。（4）测定了蛩螽亚科栖螽属，剑螽属、异剑螽属、异饰尾螽属、铲畸螽属、畸螽属10个物种的线粒体基因组序列并进行比较分析，结果显示mtDNA长度为15858-16358 bp，碱基组具明显AT偏向（69.2-72.7%）和低G含量（9.9-11.2%）；13个PCGs均以典型的ATN（ATT/ATA/ATG/ATC）作为起始密码子，终止密码子为TAA，TAG和T；除tRNASer(AGN)外，其余tRNA均可形成典型的三叶草形二级结构。螽斯科昆虫线粒体控制区的串联重复序列大小为2-259 bp，重复倍数为1.91-46，大部分物种（18/27）的线粒体控制区中都有T-stretch（7-20 bp）复制起点识别序列连接或参与形成茎环结构。截至目前发表学术论文9篇，其中SCI收录8篇。