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During a survey for Longidorids from natural vegetation in China, 8 populations of Xiphinema brevicollum Lordello & da Costa, 1961 were detected;morphometric data derived from females showed that Shanxi and Anhui populations are comparatively longer in body size (1.8 ~ 2.2μm), tail length longer in Zhejiang and Shandong populations (26 ~ 34 μm), and length of odontostyle is longer in Beijing population (88 ~ 95 μm) while position of vulva are almost constant among populations.Phylogenetic analysis using rDNA D2/D3 region and 18S yields 99.8% and 98.7% similar identity to populations from Japan (AB675667) and Taiwan (AY359856),respectively.In contrary, mtDNA COI sequence analysis by Maximum Likelihood method revealed 3 divergent groups (Group Ⅰ: Beijing population, Group Ⅱ: Shandong, Shanxi, Anhui populations, Group Ⅲ: Zhejiang populations) among the 8 sequence variants.Differences within each group (<0.22% ~ 0.33%) are regarded as intra-population variations while between COI groups (6.09%~ 6.65%) are regarded as inter-population variations.Finally, analyses using nuclear 18S and 28S rDNA expansion segments were of little use to clarify the relationship between populations of Xiphinema americanum group.Thereby mitochondrial COI multiple sequence alignments is suggested to get more adequate discriminative information to embark a thorough understanding to overcome the challenging setback of X.americanum group taxonomy.