The fragments of 350 bp in 28S rRNA from the closely related monogenea of trematoda, Neobenedenia girellaeand N. melleni are obtained by polymerase chain reaction (PCR) amplified using a couple of special primers andthen sequenced. The results show that the comparison of 28S rRNA sequences, with only a base varying in 337bp accounting for 0.3% genetic difference, from the relative species N. girellae and N. melleni parasitized on thedifferent fishes in different farms displays that they possess a very high genetic similarity of 99.7%, higher thanthat of 99.41% for the single species N. melleni sampled in different areas, and the intraspecific divergence of N.melleni is 0.59%. Meanwhile, the interspecific differences between the two Neobenedenia and three Benedenia (i.e., B. lutjani, B. rohdei and B. seriolae) range from 2.08% to11.73%. In addition, UPGMA and MP molecularphylogenetic trees are constructed and proved to be consistent with each other. Though the morphologicalcharacteristics and the results of genetic diversity for the two Neobenedenia show a high similarity, whether theybelong to a single species or not are still undefined, and the more genes of them should be further investigated, incombination with the systematical and detailed morphological study.
展开▼
