Abstract:Abstract: [Objective] Vairimorpha ceraces is a new microsporidium that isolated from the insect of Lepidoptera, Cerace Stipatana (Walker). We used 16S rDNA sequence to explore genetic status of Vairimorpha ceraces. [Methods] SSU rDNA (small subunit ribosomal RNA) of Vairimorpha ceraces was cloned and sequenced for constructing phylogenetic tree through Neighbor-joining. [Results] The core sequence of SSU rRNA of Vairimorpha ceraces with a length of 1228 nucleotides (GenBank EU267796) was successfully cloned and sequenced. Phylogenetic analysis showed that Vairimor-pha ceraces was closer to the species of Vairimorpha sp. Germany (GenBank AF124331) and Vairimorpha imperfecta (GenBank AJ131645), both isolated from Plutella xylostella. The three species of genera Vairimorpha included Vairi-morpha ceraces formed a clade with the Nosema spp. which from Lepidoptera host in phylogenetic tree. Conversely, other three Vairimorpha spp. from Lepidoptera (Vairimorpha necatrix, Vairimorpha sp. NISM12 and Vairimorpha lymantriae) were mixed with Nosema spp. from non-lepidopteran host in the other clade. [Conclusion] Combined with the biological characters, Vairimorpha ceraces was a member of genera Vairimorpha, Family Nosematidae.