Taxonomy Of Cavernicolous Millipedes In Southern China And Their Morphological Adaptations To Subterranean Life (Myriapoda,Diplopoda)

The Diplopoda is the largest class within the Myriapoda,globally encompassing 12,000 species and around 3,000 genera belong to 150 families and 16 orders.China is the country supporting the largest karstic areas in the world and a wide range of karst landscapes.As one of the largest karstic areas in China,South China karsts are home to various kinds of cave resources,including a very rich cave fauna.Cave biodiversity are often characterized by great,mostly highly localized endemism at the species level.Cave millipedes are common and representative cavernicolous animals in southern China,most of the species are troglobites,i.e.,true cave-dwellers.Therefore,cave millipedes are very important not only for cave faunas and biodiversity conservation,but also for studying the origins and evolution of cavernicoles.In this dissertation,the author carried out a preliminary taxonomic study on cave millipedes from southern China for the first time to master the composition and distributional pattern of Chinese cave millipedes and providing with the keys to all orders,families,genera and species concerned.A total of 164 species and 21 genera from 14 families and 6 orders are dealt with in this study,including descriptions of 36 new species and records of a new genus and 20 species for China.DNA barcodes techniques were used to identify species and to reveal the population division in the genus Nepalella.Furtheremore,morphological adaptation of cave millipedes to their subterranean habitats was investigated for the first time by comparing a troglobitic millipede with its epigean counterpart so as to indicate the morphological adaptations to the cave environment.1.The main results of traditional taxonomical studies are as follows:1.1 The genus Piccola is recorded from China for the first time,with description of a new species.1.2 20 species have been described and published: Hyleoglomeris baxian Liu & Tian,2015,Hyleoglomeris generalis Liu & Tian,2015,Hyleoglomeris getuhensis Liu & Tian,2015,Hyleoglomeris grandis Liu & Tian,2015,Hyleoglomeris multistriata Liu & Tian,2015,Hyleoglomeris rhinoceros Liu & Tian,2015,Hyleoglomeris variabilis Liu & Tian,2015;Desmoxytes getuhensis Liu,Golovatch & Tian,2014,Desmoxytes laticollis Liu,Golovatch & Tian,2016,Desmoxytes nodulosa Liu,Golovatch & Tian,2014,Desmoxytes phasmoides Liu,Golovatch & Tian,2016,Desmoxytes simplipoda Liu,Golovatch & Tian,2016,Desmoxytes similis Liu,Golovatch & Tian 2016,Desmoxytes variabilis Liu,Golovatch & Tian,2016;Nepalella jinfoshan Liu,2017,Nepalella lobata Liu,2017,Nepalella troglodytes Liu,2017,Nepalella wangi Liu,2017;Paracortina yinae Liu & Tian,2015,Paracortina zhangi Liu & Tian,2015.1.3 36 new species are provisionally delimited and will be published in the near future: Epanerchodus latus n.sp.,Epanerchodus tujiaphilus n.sp.,Epanerchodus serratus n.sp.,Epanerchodus parvus n.sp.,Epanerchodus gladiatus n.sp.,Epanerchodus securiformis n.sp.,Epanerchodus acutus n.sp.;Pacidesmus elongatus n.sp.,Pacidesmus trilobatus n.sp.,Pacidesmus uncatus n.sp.;Trichopeltis bellus n.sp.,Trichopeltis intricatus n.sp.,Trichopeltis reflexus n.sp.;Eutrichodesmus alveolatus n.sp.,Eutrichodesmus duanensis n.sp.,Eutrichodesmus alveolatoides n.sp.,Eutrichodesmus tricornutulus n.sp.,Eutrichodesmus bidigitatus n.sp.,Eutrichodesmus tangae n.sp.;Skleroprotopus longipes n.sp.,Skleroprotopus gracilipes n.sp.;Glyphiulus longigonopus n.sp.,Glyphiulus yueicus n.sp.,Glyphiulus ningnanensis n.sp.,Glyphiulus brevidistalis n.sp.,Glyphiulus basaloides n.sp.,Glyphiulus wanghuadytes n.sp.,Glyphiulus securiformisn.sp.,Glyphiulus tabulatus n.sp.,Glyphiulus jinjiensis n.sp.,Glyphiulus multifidus n.sp.,Glyphiulus kunmingensis n.sp.,Glyphiulus brevus n.sp.,Glyphiulus sinuatoprocessus n.sp.,Glyphiulus longidigitatus n.sp.,Glyphiulus brevidigitatus n.sp..2.The molecular analysis on genetic diversity in the genus Nepalella involved 10 new nucleotide sequences,combined 3 from different Chordeumatida genera(Altractosoma,Brachychateuma and Craspedosoma)as the near-outgroup.Using MEGA6 software,genetic distances were calculated between all Nepalella species in the dataset,intrespecific distances range from 8.5%–15.9%,intraspecific distances 0.2%–6.8%.Two additional non-Chordeumatida sequences were added as the far-outgroup outgroups to the dataset.A phylogenetic reconstruction was accomplished using a maximum likelihood statistical method and MEGA6.Nepalella is clearly separated from all outgroups taxa.In addition,the analyzed species of Nepalella can be divided into two groups,while the results of DNA barcoding are similar to those obtained applying the morphology-based taxonomy of Nepalella.3.To investigate the morphological adaptations of cavernicolous millipedes to their cave life,30 different characters were amassed from species belonging to 4 different orders(Glomerida,Polydesmida,Chordeumatida,Spirostreptida)and 6 different families(Glomeridae,Paradoxosomatidae,Polydesmidae,Haplodesmidae,Megalotylidae,Cambalopsidae),which were utilized to compare cave troglobites and epigean species of the same genera.While 10 characters only apply to a few phylogenetic groups,20 characters could be scored for all families.Of these 20,four characters were discovered to be convergently evolved in all studied troglobitic millipedes.These characters representing potential morphological cave adaptations are(1)a longer body;(2)a much lighter body colour;elongation of(3)the femora and(4)the tarsi of walking legs;(5)elongation of female antennae.The study clearly shows that peculiar morphological changes occurred convergently in different,unrelated millipede orders and families as a direct adaptation to cave life.