Abstract: Objective To identify the taxonomy for Ascaridia galli by investigating its morphological and molecular characteristics and phylogenetic analysis. Methods The Ascaridia galli was isolated from the small intestines of chickens collected in Huangshan area, Anhui Province, and observed under light microscope and scanning electron microscope for the morphology. Then genes ITS and COⅠ of Ascaridia galli were amplified, cloned and analyzed for homology and phylogeny. Results Morphological observation showed that the Ascaridia galli was milky white after fixing the dead body. The tail was straight for the female, curly for the male. Three lips, measuring equally in size, arose at the head, and 10 pairs of papillae were seen at the tail of male. The length of COⅠ and ITS genes were 655 bp and 1 034 bp, respectively. Phylogenetic trees based on COⅠ and ITS genes revealed that Ascaridia galli isolates from Huangshan area had the highest homology with those from other countries or regions, with COⅠ and ITS identity being up to 100% and 99. 9% respectively. This nematode Ascaridia galli was clustered in one clade. Conclusion Analysis of the morphological and molecular characteristics for Ascaridia galli can lay a foundation for identification, prevention and control of this species.

Key words: Ascaridia galli , Morphological characteristics, Molecular characteristics, Phylogenetic analysis