Analysis Of Mitochondrial Gene And Feeding Habit Of The Dominant Species And Molecular Classification Of The Larvae In The Genus Unionicola(Acari:Unionicolidae)in China

In this research, the complete sequence of mitochondrial genome was amplified by Standard PCR and Long PCR for Unionicola arcuata, and its whole sequence was14574bp in length. In the complete sequence of mitochondrial genome for U. arcuata, the percentages of A+T apparently higher than G+C, high content of A+T for mitochondrial genome from mites was commonly phenomenon. The complete sequence of mitochondrial COI gene for U. arcuata was1539bp in length, which totally encodes512amino acids with ATG as start codon, TAA as stop codon, TGA as encoding Trp instead of a termination codon, and the content of Leu is the highest, while Cys is the lowest. Using mitochondrial COI gene sequence to analyzed phylogenetic relationships between U. arcuata and other unionicolid mites, we found that the U. agilex might be the first separated from ancestral species, and U. arcuata, U. foili and U. ypsilophora might originate in the same ancestor.Be analyzed sequence divergences and phylogenetic relationships of the mitochondrial12S rRNA gene among groups of U. arcuata, we found that the12S genetic divergence among groups of U. arcuata from the same host species never exceeded0.5%, whereas the divergence among groups of U. arcuata from different host species was6.7%or higher. The groups of U. arcuata from different molluscan hosts may actually represent cryptic species of Unionicola. The biogeographic separation among groups of U. arcuata from the same species of host had little impact on divergence in12S. However, host selection and utilization resulted in a high degree of genetic differentiation among U. arcuata from different freshwater mussels.Using mitochondrial16S rRNA gene partial sequence to analyzed alimental composition of U. arcuata and U. ypsilophora, the result shows that utilized DNA of Cristaria plicata, DNA of entire individual and splanchnic tissues for U. arcuata and U. ypsilophora as templates were amplified the same sequence, and the length was587bp; Containing undigested DNA of C. plicata in splanchnic tissues for U. arcuata and U. ypsilophora. U. arcuata and U. ypsilophora were collected from the gills and feeding on the tissues of C. plicata. U. arcuata and U. ypsilophora might be parasitic association with C. plicata.Using mitochondrial12S rRNA gene partial sequence as a molecular marker to succeed on classified four species of unionicolid larval mites from China, these larval mites were U. ypsilophora, U. arcuata, U. chelata and U. agilex. Morphological description of these four species of unionicolid larval mites from China, and the key to the larval mites was listed. The larval mites show some the same morphological characters:humeral seta in dorsum of the larval mites was a widest and longest seta; excretory pore plate and excretory pore were oval in shape, and never seta grow in excretory pore; ventral seta4was a longest seta in excretory pore plate around; leg â…  for larval mites was the shortest leg, while leg â…¢ was the longest leg, the length of leg â…¡ was between leg â…  and leg â…¢; Only one seta Trl grow in trochanter of leg â…  from the larval mites, this seta was short and thick; tarsus in leg of the larval mites was a longest segment.