| This essay focuses on the freshwater crab of Potamiscinae in Hengduan Mountains Region(HMR)to conduct the primary study on the morphological taxonomy and molecular phylogeny based on the extensive and indepth field survey and sample collection in this region.Based on the field survey and taxonomic study,we have found and described one new genus and five new species from Jinsha River Basin,which includes one new genus Falcatopotamon gen.nov.,with four new species,Falcatopotamon banqiaopingense sp.nov.,F.jinjiangense sp.nov.,F.zhongjiangense sp.nov.and F.zhongyiense sp.nov.,and one new species Artopotamon latopeos sp.nov.of Artopotamon Dai&Chen,1985.The phylogenetic analyses Based on the mitochondrial DNA marker(16S rDNA)and nuclear markers(28S rDNA,ITS2),and comparative morphological evidence in G1 terminal segment from the four new species of Falcatopotamon gen.nov.by using scanning electron microscopy technique,provide a strong support for the new taxa.We study the evolutionary history and the occurrence of species diversity by reconstructing the phylogeny of the freshwater crab of Potamiscinae in HMR based on the 52 nuclear genes for the first time.The involved group including 23 genera and 47 species of Potamiscinae sampled from China,of which,13 genera and 35 species were sampled from HMR,respectively accounting for 68%and48%of the number of genera and species distributed in HMR.With the molecular dating analysis and ancestral area reconstruction,we primary study the evolutionary process of the biodiversity formation of the freshwater crab in HMR.The main conclusions were as follows:(1)The ten endemic genera of HMR cluster together to form a clade(clade I),and all of them with a common character that the exopod of the third maxilliped without flagellum.Based on this,we suggest to put them together to form a new tribe,Montopotamon.Within clade I,Tenuipotamon purpura,Pararanguna semilunatum.Parvuspotamon yuxiense were the three ancestral subclades of clade I.(2)Phylogenetic results indicated the non-monophyly of three genera including Aparapotamon Dai&Chen,1985,Tenuipotamon Dai,1990 and Potamiscus Alcock,1909,which indicated the underestimated generic diversity.At the species level,Aparapotamon grahami(Rathbun,1929)sampled from different population were not monophyletic.F.zhongjiangense clustered with F.zhongyiense,A.molarum Dai&Chen,1985 clustered with A.inflomanum Dai&Chen,1985,and the four taxa are nonmonophyletic at the species level.All the above indicated the existence of cryptic species and the underestimated species diversity.(3)Molecuar dating analysis reveals that the divergence time of clade ? is younger than clade ? at about 6.2 Mya in late Miocene,and that the divergence of all existing genera occurred between 6.2 Mya and 4-Mya,consuming about 2.2 My.The geological history of this region especially the rapid uplift at approximately 8 Mya and 3.6 Mya is considered to be critical to explain the in situ diversification and speciation of these genera.(4)Based on the biogeographical analysis of Aparapotamon,we find that the most recent common ancestor(MRCA)of Aparapotamon was narrowly distributed in Jinsha River Basin.Our interpretation is that the in situ speciation resulting from the geographic isolation caused by the rapid uplift at about 3.6 Mya.At the same time,the river capture/reversal event of major rivers in HDM provided approaches for the MRCA of A.grahami and A.gracilipedum(Chen&Chang,1982)to dispersal into the Qinling Mountains Region.The study testified that the tectonic processes and the evolution of the drainage systems played an important role in the speciation of Potamiscinae in HDM.Meanwhile,this region is waiting for a long-term field survey and the specific freshwater crab biodiversity of this region is waiting to compile the?freshwater crabs species red list?and protection of biodiversity. |
PDF Full Text Request