Two populations of Xiphinema persicum n. sp. belonging to the X. americanum-group, were recovered from Semnan province, and described and illustrated based upon morphological, morphometric and molecular data. The type population of the new species is characterized by 2233–2736 μm long females, offset lip region, anteriorly flat to slightly rounded and separated from the rest body by constriction, 82–87 μm long odontostyle, two equally developed genital branches with visible endosymbiont bacteria in ovaries under light microscope, vulva at 52.8–55.5%, 27–32 μm long dorsally convex and ventrally straight to slightly convex tail with a rounded tip, or having a wide mucro-like differentiation, rare male with six ventromedian supplements and four juvenile developmental stages. The new species was morphologically compared with six similar species, X. bricolense, X. californicum, X. incertum, X. pachtaicum, X. santos and X. simile. The latter species has closest morphology and phylogenetic affinities to the new species in both large subunit and internal transcribed spacer 1 (LSU and ITS1 rDNA) trees; but X. persicum n. sp. has four juvenile developmental stages (vs. three), longer odontostyle, and posteriorly located guiding ring compared to it. The phylogenetic relationships of the endosymbiont bacterium of the new species with other isolates was reconstructed using the partial sequences of 16S rDNA.

百日草属的两个种群。sp。属于美洲X.-组，从Semnan省回收，并根据形态学，形态计量学和分子数据进行描述和说明。新物种的类型种群的特征是长2233–2736μm的雌性，唇部偏移，前部平坦至略圆，并通过收缩与其余身体分开，长82–87μm的齿形，两个同样发达的生殖器分支，带有共生菌光学显微镜下卵巢中的细菌，外阴位于52.8–55.5％，长27–32μm，背侧凸，腹侧笔直至稍凸起，尾巴呈圆形，或具有宽的粘液样分化，雄性稀少，有六种腹膜补充剂和四种青少年发展阶段。在形态上将新物种与六个相似物种X. bricolense进行了比较。X. californicum，X. incertum，X. pachtaicum，十桑托斯和X.比喻。后者在大型亚基和内部转录间隔区1（LSU和ITS1 rDNA）树中具有与新物种最接近的形态和系统亲和力。但是X. persicum n。sp。与它相比，它具有四个青少年发育阶段（相对于三个），更长的齿形和位于后方的导向环。利用16S rDNA的部分序列重建了新物种内共生细菌与其他分离株的系统发育关系。