Taxonomy Of Arrenuridae In China And Its Geometric Morphometrics

Family Arrenuridae belongs to the Subclass Acari,Order Trombidiformes,Subcohort Hydrachnidiae,and Superfamily Arrenuroidea;and is the most abundant and ecologically important group in water mites.By 2020,8 genera,13 subgenera,1114 species were reported all over the world,however,only 35 species in 1 genus and 6subgenera in China,accounting for only 3.14% of known species in the family.At the same time,due to the shortage of available morphological characteristics for water mite taxonomy,and in order to meet with the needs of Arrenuridae taxonomical research,narrow its knowledge gap in China with the world,this study was carried out about arrenurid classification and faunal characteristics in China,and its geometric morphometrics.The main research content and results are as follows:1.ClassificationBased on more than 1000 arrenurid specimens from 24 provinces,autonomous regions and municipalities in China,52 species in 1 genus,5 subgenera were identified,including: 13 new species and 5 new record species;Subgenus Rhomborificias was regarded as the synonym of subgenus Arrenurus,2 species were preoccupied in scientific names and renamed,and 2 species were regards as new synonyms.Meanwhile,a total of more than 400 slide specimens were mounted,11 electron microscopy pictures and 1 color feature picture were taken,and 47 feature figures were drawn.And at the same time,a key to the species,the genera and subgenera of Chinese Arrenuridae were compiled.The details are as follows:(1)13 species new to science: Arrenurus(Arrenurus)jaggedis Zheng,Guo &Zhang,2022;Arrenurus(Arrenurus)pseudodistinctus Zheng,Guo & Zhang,2022;Arrenurus(Arrenurus)unguiculus Zheng,Guo & Zhang,2021;Arrenurus(Arrenurus)menglaensis Zheng,Guo & Zhang,2022;Arrenurus(Arrenurus)pseudonemani Zheng,Guo & Zhang;Arrenurus ancoralis Zheng,Guo & Zhang,2021;Arrenurus(Arrenurus)yanchengis Zheng,Guo & Zhang,2022;Arrenurus(Truncaturus)linguaus Zheng,Guo& Zhang,2022;Arrenurus(Megaluracarus)guantingensis Zheng,Guo & Zhang,2022;Arrenurus(Arrenurus))circinatus Zheng,Guo & Zhang,2022.Arrenurus(Arrenurus)chonqingus Zheng,Guo & Zhang sp.nov.;Arrenurus(Truncaturus)guangxis Zheng,Guo & Zhang sp.nov.;Arrenurus(Megaluracarus)xiannuis Zheng,Guo & Zhang sp.nov..(2)Five new record species to Chinese fauna: Arrenurus(Truncaturus)isikliensis Boyaci & (?)zkan,2004;Arrenurus(Arrenurus)turgidus Koenike,1911;Arrenurus(Arrenurus)affinis Koenike,1887;Arrenurus(Megaluracarus)ussuriensis Sokolow,1931;Arrenurus(Arrenurus)crassicaudatus Kramer,1875.(3)About the subgenus Rhomborificias: Arrenurus(Rhomborificias)lincangensis Jin & Li,1993 was regarded as the female of Arrenurus(Arrenurus)xini Jin & Wiles,1993.The original Arrenuridae was removed,and the subgenus established according to the mite was also removed accordingly.(4)Homonym: Arrenurus(Arrenurus)bilobatus Jin & Li,1996 was preoccupied by Arrenurus(Megaluracarus)bilobatus Viets,1925,and renamed as Arrenurus(Arrenurus)leishanus nom.nov.after Leishan where it was collected;Arrenurus(Micruracarus)bipetiolatus Jin & Wiles,1996 was preoccupied by Arrenurus(Megaluracarus)bipetiolatus Viets,1954,and renamed as Arrenurus(Micruracarus)yibinus nom.nov.after the place where it was found.(5)Arrenurus aculcatiprons Piersig,1906 syn.nov.is synonym of Arrenurus(Megaluracarus)rostratus Daday,1898;and Arrenurus palemkangensis Piersig,1906 syn.nov.is synonym of Arrenurus(Micruracarus)madaraszi Daday,1898.2.Geometric morphometricsGeometric morphometrics was used to analyze the gland position of dorsoglandularia 1-4 of 128 arrenurid samples and the caudal structure morphology of156 arrenurid samples,and the variation trend of both characteristics was clarified.The analysis method of typical variables was used to evaluate the differences between subgenera and species,and the results showed that the samples in the same group were clustered together,and the analysis method of typical variables could correctly distribute the samples to their respective groups.At the same time,the results of Mahalanobis distance comparison showed that the differences between subgenera and species were significant(P < 0.05).Geometric morphometrics methods were also used to identify three similar species of the subgenus Arrenurus(A.acoralis,A.affinis,A.pseudoaffinis).In the scatterplot and Mahalanobis distance comparison analysis based on typical variable analysis,the difference between the two features was significant(P < 0.05).From this,geometric morphometric methods can be used for species identification in the family Arrenuridae.In summary,this study showed that the geometric morphometric method can quickly and effectively distinguish between subgenera and between species of Arrenuridae.At the same time,it was further confirmed that the cauda morphology and the position characteristics of the gland position of dorsoglandularia 1-4 could be used as the taxonomic features of Arrenuridae.3.Characteristics Analysis of Chinese faunaThe unitary pattern and accumulated patterns of analysis methods were used to analyze the Chinese faunal characteristics of the family Arrenuridae,including 52 species in 1 genus,5 subgenera.The results showed that there were 29 species belonging to the Oriental pattern,accounting for 55.8%;the number of species with the pure Oriental pattern and trans-regional patterns containing the Oriental pattern reached to38 species,accounting for 73.1%,which shows that the Oriental species are in a dominant position at specific level,and have a strong connection with the Palaearctic Realm(40.3%),followed by the Nearctic Realm(3.8%),African Realm(1.9%)and Neotropical Realm(1.9%),and Australian Realm.While in the zoogeographic division of China,the number of Central China pattern was the largest(12 species),accounting for about 23.1% of the total,while the species number belonging to pure Central China pattern and trans-regional patterns containing Central China was 25 species,accounting for 48.1% of the total,which shows that the species of Central China are in a dominant position at specific level,and have a strong connection with Southwest Region and Southern China Region,followed by the North China Region,and there is only weak lineage with Northeast Region,Inner MongoliaXinjiang Region and Qinghai-Tibet Region.