Sequence Analysis To Mitochondrial12S RRNA Gene And Molecular Identification To Parasitic Mites In Mussels

Water mites belong to one genus, Unionicola only, are common parasites of freshwater mussels. It is questionable subgeneric classification is based on characters of the adult, but comparative to characters of larvae, could accurate to determinant the phylogenetic position of adult, the Larvaes of water mite are small, Subgeneric classification is very difficult to rely upon morphological characters. Here, a portion of the mitochondrial12S rRNA gene from egg of water mite which was parasitic on Cristaria plicata was amplified by molecular biological technology, sequenced and comparative sequence analysis with mite water of GenBank. Identifying the species of eggs, describing the larvae and nymphan hatched from eggs. The result showed that the nucleotide homology of the mitochondrial12S rRNA gene of egg compared with Unionicola sp. was94.8%, the genetic distances was the lowerst, belonged to interspecific genetic differences. The eggs were the subgeneration of Unionicola sp. Comparative Parasitic water mite. Unionicola sp. and U. arcuata, the genetic differences of12S rRNA gene and morphological characteristics, the results of this study was suggested that Unionicola sp. was a cryptic species of U.arcuata.On the other hand,12S rRNA gene complete sequences of U. brevipedalis sp. which were parasites in Cristaria plicata was amplified, sequenced and analyzed. To acquire12S rRNA gene complete sequences of U. brevipedalis sp.648bp, the nucleotide distances with other mite water was0.987(with U. chelata)～1.073(with U. formosa), gnerally higher. Molecular tree showed that U. brevipedalis sp. formed one clade alone, closed to U. imamurai, acording to the Special morphological characteristics of acetabular plates, we inferred that U. brevipedalis sp. was the relatively ancient water mite.