The Preliminary Study On Diversity Of Bdelloid Rotifer In China

Bdelloid rotifers(Rotifera: Eurotatoria: Bdelloidea)are a group of microscopic invertebrates known for their obligate parthenogenesis and exceptional resistance to extreme environmental stresses(e.g.,drying,freezing,ionizing radiation).Having these remarkable biological features,bdelloids could easily survive in unfavourable conditions,including extreme tropical and polar habitats.The minute size of bdelloids allow their long-distance dispersal by wind,water and animals.Besides,they are easy to collect and culture,so that they are already being used in taxonomy,ecology and evolution experimental studies as ideal model organisms.There are over 480 described clonal bdelloid species in the fauna,inhabiting both waterbodies(mainly freshwater lake,pond and stream)and terrestrial habitats,such as moss,lichen,tree bark,soil and litter.Comparably rarely,bdelloids are found in marine and brakish waters.In China,only 43 clonal bdelloid species have been reported prior to 1998,and there was no update for almost 20 years untill 2016,when the the record was updated to 48 species.During 2017-2018,a survey on bdelloids was conducted,which supplementing a background data that for the further estimatation of biodiversity on rotifers in China.A taxonomic study on bdelloid rotifers was made during the period from September 2017 to October 2018 in 11 locations in China.Under this study,over 61 samples were collected from terrestrial(moss,lichen,soil,litter)and aquatic(freshwater,brackish)habitats.In total,61 clonal species(including ‘subspecies')of bdelliod rotifers have been identified.Forty-one taxa of the species rank and 1 genus among the found ones are new records for China that increases the species list of local bdelloid fauna from 48 to 89 species-rank taxa.The detailed information of their distribution and habitat preference is present,for which reviewed published literature records rotifers but did not provide any data in on their habitat type.Among these new records,41 species are for the first time reported for the Oriental region.Redescriptions and illustrations of rare species of bdelloids new for Chinese fauna are given,and the scanning electranic microspic images of the trophi of Philodina parvicalcar are presented,which revealed additional 2 thinner major teeth on one side.Additionally,18 sequences of the cytochrome oxidase subunit 1(COI)gene of 8 morphological bdelloid species were acquired.It revealed that there are emdemic species existed in China among those morphological species(Adineta cf.ricciae,Adineta beysunae and Adineta cf.barbata).Philodina acuticornis,Rotaria sordida and Adineta vaga seems to be cosmopolitan(clusters with the samples from the USA,similar enough to some European R.sordidas,very close to the one from Australia,respectively).These data gave new evidence on bdelloids' distributions showed that they are not as cosmopolitan as was considered priviously,and there are ‘endemic' lineages in China,provided new evidence on their biogeography.