Classification, Diversity Distribution And Conservation Research Of Freshwater Crabs Of Crabidae In Mainland China

In the present dissertation,4 new species and two new genera of Potamidae crabs in mainland China are described in detail including Arquatopotamon jizushanense gen.n.,sp.n.,Semicirculara lincangense gen.n.,sp.n.,Yarepotamon huapingense sp.n.and Sinopotamon baokangense sp.n.And designation a neotype for Sinopotamon chengkuense Huang,Luo&Liu,1986 with redescribe.The Arquatopotamon jizushanense gen.n.,sp.n.third maxilliped exopod without flagellum,G1 long,distal part of subterminal segment and terminal segment arch shaped,terminal segment tongue-shaped,distinctly curved ventralwards(ventral view).The Semicirculara lincangense gen.n.,sp.n.third maxilliped exopod without flagellum,G1 terminal segment semicircular shaped(ventral view),distal part of terminal segment elongated with a ventral curved semicircular lobe.The Yarepotamon huapingense sp.n.third maxilliped exopod with stick-shaped flagellum,G1 slender,dorsal flap of terminal segment with trilateral protrusion,tip sharped.The Sinopotamon baokangense sp.n.distal part of fingers spoon-shaped,G1 long,dorsal flap of terminal segment with semicircular protrusion,inner-distal angle of G1 elongated,with semicircular lobe.The Sinopotamon chengkuense third maxilliped exopod with flagellum,G1 stout,subterminal segment about 4.7 times as long as terminal segment,and terminal segment slightly curved dorsal-inwards(ventral view),terminal segment two lobes hugged,and the median of terminal margin slightly concave.The habitat,type specimens and distribution of those species have been recorded.Based on the reclassification of some genura and species,three synonym species have been founded.Through,a checklist on the classification and distribution of the freshwater crabs in China are assemblied.There are 307 species and 44 genera,and two families in China(of which,41 species was distributed in Taiwan).One genus and 27 species are assigned to the family Gecarcinucidae,and 43 genera and 280 species are assigned to the family Potamidae.Meanwhile,a high degree of endemicity is also presented with a total of 298 species and subspecies(97%)and 36 genera(81%),respectively.Of which,239 species and subspecies in 42 genera occurred in mainland China.It contributes China as the center of diversity and endemicity for freshwater crabs in global.In the present study,the field investigations of our lab was reviewed that conducted across 21 provinces from Oct 2000 to Oct 2016.As a result,over 5000 potamid specimens were collected during the field surveys,and a total of 131 species in 24 genera were identified based on morphological taxonomy.Combined with nearly 700 survey localities in recent 16 years and those collected from the historic records and collection information of specimens in related literatures,a specimen-level distributional dataset was set up which containing a total of 1,665 localities.Five distribution centres have been revealed,which the southeast of Wu and Daba mountains located in upper and middle Yangtze River is the most species rich area with about 29 species.129 stenochoric species were revealed by GIS,about 54.4%of the total number of potamid crabs in mainland China.Two distribution centres of the stenochoric species were identified.One was the southeast of Yulong and middle of Yunnan-Guizhou Plateau included 21 species and another was the mid-east of Wuyi Mountain harbours 16 species.Comparing with the Pearl River Basin and Yellow River Basin,the species diversity of freshwater crabs in the Yangtze River Basin was the highest.But the trend of the species diversity in the Yangtze River has been declined.All the 222 species were assessed against the IUCN(2012)Red List Categories and Criteria(version 3.1)based on present specimen-level distributional dataset.The reassessment shows that 9 species are Endangered,27 Vulnerable,5 Near Threatened,88 Least Concern and 93 Data Deficient.There were a total of 36 species under threatened,and the proportion of the threatened species was 16.2%,nearly equal to the global proportion(16.3%).The threat categories of the 83 species were changed after reassessment,and the 79 Data Deficient species have been assigned to 8 Endangered,22 Vulnerable,4 Near Threatened,and 45 Least Concern.And the threat level of two species has been promoted and two species reduced.There were 9 provinces under threatened,of which,the Yunnan province was particularly apparent with 1 5 theratened species,followed by Guizhou and Hunan provinces with four theratened species separately.Among the 93 data deficient species,more than 80%(75 species)of them is known from Extents of Occurrence less than 1000 km2.In order to understand the status of the data deficient species,24 species which distributed in 7 provinces ware investigated,but the species ware unobserved.The threatened level of the potamid species in mainland China may be higher than global freshwater crabs.Three factors predominantly threatened freshwater crabs included habitat loss/degradation,human disturbance and invasion of alien species.The species which assessed to Data Deficient mainly distributed in the southern coastal areas and Yunnan province,with 50 and 10 species separately,meaning there is insufficient information to assess their status and extensive new field surveys were needed to obtain a comprehensive assessment for those species.Nationwide long term monitoring and assessing of freshwater crabs and compiled the?China freshwater crabs species red list?were advocated,and better-informed efforts to conserve freshwater crab diversity should benefit freshwater ecosystem services.