Nemacheilidae Cavefishes Of China-Taxonomy,Adaption And Zoogeography

Cavefish refers to fish that must rely on the groundwater environment to complete part or all of its life history in its natural state.According to this definition,cavefish can be divided into two types: typical cavefish and atypical cavefish.Nemacheilidae belongs to Cypriniformes,which is small fish widely distributed in various parts of the country.Burrow fish species in Nemacheilidae belong to the genus Triplophysa,Troglonectes,Oreonectes,Heminoemacheilus,Paranemachilus,Schistura and Yunnanilus,which studies started lately in China and existed many problems.This study mainly revised,categorized,and re-described the species of the cave fishes of the Nemacheilidae.On the basis of taxonomic studies,the zoogeography and distribution pattern of burrowing fishes in the family Nemacheilidae were further explored,and the resources of the fishes in the burrows of the Nemacheilidae are further analyzed,and specific suggestions for the protection of their resources are provided.According to the results of taxonomic studies,Divided Triplophysa dongganensis,Triplophysa jiarongensis,Triplophysa lihuensis,and Triplophysa lingyunensis into genus Troglonectes and its names have been corrected to Troglonectes dongganensis,Troglonectes jiarongensis,Troglonectes lihuensis,Troglonectes lingyunensis;Troglonectes huanjiangensis and Troglonectes elongatus are one species and belong to the genus Troglonectes.The name is corrected to be Troglonectes huanjiangensis;Triplophysa longibarbatus and Homatula posterodarsalus are one species,and the name is corrected to be Troglonectes longibarbatus;Oreonectes donglanensis and Oreonectes duanensis was divided into Troglonectes and their names were corrected to Troglonectes donglanensis and Troglonectes duanensis.Combining Oreonectes daqikong and Homatula maolanensis into one species and dividing it into the genus Troglonectes,the name is corrected to Troglonectes maolanensis.The Schistura dabryi microphthalmus,a subspecies of the family Schistura dabryi,was promoted to species and renamed Schistura microphthalmus.After the species amendment,there are 49 species of cavefishes in Nemacheilidae,including 21 species of Triplophysa,16 species of Troglonectes,5 species of Oreonectes,3 species of Heminoemacheilus,2 species of Paranemachilus,1 species of Schistura,and 1 species of Yunnanilus.Based on the results of the study,the traits of the genus cave fishes were determined,and an interindividual retrieval table was established for the genus Triplophysa Troglonectes,Oreonectes,Heminoemacheilus,Paranemachilus,Schistura and Yunnanilus,which were established separately.The retrieval tables for the fish species in the caves of the genus of each genus re-delineate the species of fish in each genus of the burrow family.The main distribution areas of cave fishes in the areas of the Yunnan-Guizhou Plateau and its surrounding karst landforms,there are mainly north Guangxi,northwest and south Guizhou from administrative divisions,and also south Yunnan,southeastern Chongqing,and Hunan Province.In the northwest,there are also some species(mainly plateau clams)distributed.Yunnan-Guizhou Plateau belongs to the high-prototype subtropical monsoon region.The annual average temperature is between 5-24°C and the wet and dry seasons are distinct.The Yunnan-Guizhou Plateau has a karst landscape distribution.There are mainly caves and underground rivers in the underground.The distribution of the cavefishes in the genus Triplophysa can be summarized in three distribution areas: the Nanpanjiang River in the upper reaches of the Pearl River in the south of Yunnan Province,the Hongshui River in the upper reaches of the Pearl River in the junction between Guangxi and Guizhou,and the upper reaches of the Yangtze River in the junction of Hunan Province and Chongqing City.This should be the result of the proliferation and differentiation of the Tibetan Plateau plateau species of the genus Triplophysa along the Pearl River water system and the Yangtze River water system;most of the species of the genus Oreonectes are associated with the distribution of the genus Troglonectes,and the distribution area of the genus Troglonectes is relatively high.The height of the hole is lower,from south to north,with increasing elevation,the number of species of fishes in the genus Oreonectes is decreasing and the number of fish species in the genus Troglonectes is increasing.This should be ground fish of genus Oreonectes of the northward spread and further differentiation along the Pearl River Basin.The result of the spread to the north and further differentiation;genus Paranemachilus are distributed in the west of Guangxi and belong to Yujiang,the largest tributary of the Mid-west river system in the Pearl River Basin.Genus Heminoemacheilus are distributed in the Hongshui River Basin in the northwest of Guangxi and the Zuojiang River system in the Yujiang River tributary in the west of Guangxi;Schistura microphthalmus in the genus Schistura are distributed in the central Guizhou Province and belong to the Wujiang River system in the upper reaches of the Yangtze River;Yunnanilus bailianensis is located in the central part of Guangxi Province and belongs to Liujiang,the second largest tributary of the Zhongxi River in the Pearl River Basin.There are a total of 49 species of cavefishes in Nemacheilidae,which have high species diversity and genetic diversity,and have very large scientific research value.However,due to the limited ecological environmental carrying capacity of groundwater,the absolute number of populations is small,and the population resilience is weak.External disturbances such as environmental destruction and over-fishing have caused disturbances in the status of the fish resources in the caves of the Nemacheilidae,and the protection of species is imminent.