A Re-appraisal Of Environmental Indicator Of Biological Freshwater Crabs Genus Tenuilapotamon And Its Phylogenetic Research

In the practical application of biological monitoring,different indicator organisms can be selected according to different environmental monitoring,so the selection of environmental indicator organisms is the key point.As the common crustacean,Freshwater crab is widely distributed in China,with a large number of animals.Because it lives in mountain streams,has a mixed diet,and is sensitive to environmental changes,its population distribution can effectively indicate the local water quality,vegetation and other ecological indicators,Therefore,it is expected to become an important environmental indicator organism.The most widely distributed representative of Freshwater crab is Potamoidae.The most representative genus of Tenuilapotamon is found in the Chinese liquor super production areas.The genus Tenuilapotamon currently includes 3 species and 6 subspecies,and there are many subspecies within the genus that urgently need to be reorganized.This study aims to clarify the classification and phylogenetic relationship of the genus Tenuilapotamon,providing important value for it to become an environmental indicator organism.Through comprehensive geographical distribution,morphology,phylogenetic analysis,genetic distance,divergence time,etc.,a clear classification system of the genus Tenuilapotamon was obtained,and some mitochondrial comparative genomics methods were further introduced for in-depth analysis.The main conclusions are as follows:1.The distribution range of the genus Tenuilapotamon almost covers the entire super production area in the upper reaches of the Yangtze River where liquor is produced.For the first time,it is proposed that one of the important factors that can be used to monitor liquor production is water quality.Compared with chemical monitoring,biological monitoring is more sensitive and comprehensive.Therefore,selecting suitable environmental indicator organisms in the region has great value.2.Morphological observation found that except for the Tenuilapotamon joshuiense and the Tenuilapotamon inflexum,the subspecies included in the Tenuilapotamon were difficult to distinguish when observing the distinguishing characteristics of male first abdominal limbs.Further observation found that the shape of the first abdominal limb of the Tenuilapotamon latilum latilum is very similar to that of the Tenuilapotamon latilum anshunense,which may be synonym,and needs to be verified by comprehensive molecular evidence.3.The phylogenetic analysis further confirms that the T.latilum latilum and T.latilum anshunense can merge and be named T.anshunense.At this point,the genus Tenuilapotamon has a clear classification system,and a total of 7 species have been reorganized,including: T.anshunense,Tenuilapotamon kaiyangense,Tenuilapotamon huisuiense,Tenuilapotamon bijiense,Tenuilapotamon shuichengense,T.influxum,and T.joshuiense.4.Mitochondrial comparative genomics analysis results show that the genes of the genus Tenuilapotamon are relatively conserved and there is no rearrangement of mitochondrial genes,with 14 genes encoded in the R chain and the remaining genes encoded in the F chain.There are four types of starting codons: ATG,ATA,ATT,and ATC,and three types of ending codons: TAA,TAG,and incomplete T.The base composition is more inclined towards AT-skew,with different overlapping regions,interval regions,and compact regions,as well as relatively stable regional intervals or overlapping lengths.The majority of t RNA mismatches occur due to G-U mismatches,and compared to the stem ring structures in other secondary structures,there are few changes in the anti codon ring and anti codon stem.The base length of the variable ring varies,ranging from 4-6 bp,the results of mitochondrial comparative genomics support traditional morphological results,the T.latilum latilum and T.latilum anshunense can merge and be named T.anshunense.