Abstract：
The family Criconematidae is a remarkable group of nematodes, containing roughly 600 nominal root-ectoparasitic species, of which many species are known to be significant agricultural pests. Strikingly, our phylogenetic analyses based on 18S, D2-D3 of 28S rRNA, and COI mtDNA sequences of criconematid species, supported by tree topology tests (SH and AU tests), revealed that almost all studied genera, including Criconema, Ogma, Crossonema, Discocriconema, Hemicriconemoides, Criconemoides, Mesocriconema, and Lobocriconema, are not monophyletic groups, a finding that is partly contrary to those of previous studies on these groups. Our results suggest that key morphological characters used in the classification of Criconematidae are the consequence of convergent evolution. It is clear from our studies that the species status of at least 40 sequences of criconematid species from GenBank must be either revised or reconsidered, with analyses based on a polyphasic approach that includes different tree- and distance-based molecular species-delimitation methods (bPTP, GMYC, ABGD1, and ABGD2). Our studies found the ABGD2 output of the automatic barcode method to agree remarkably well with established species delimitations, while in general, the four species-delimitation results corresponding to three barcode regions forwarded significantly more putative species compared to those originally considered. This study also characterised for the first time the populations of Criconemoides myungsugae and Discocriconemella hensungica associated with Vietnamese ginseng, one of the most precious and rare ginseng varieties in the world. Although these populations are morphologically in agreement with the original descriptions of C. myungsugae and D. hengsungica, their molecular data display notable variations compared to the sequences deposited in GenBank. These species demonstrate clearly the immense molecular variations that can be observed in several species of the family Criconematidae.
摘要：
龙舌兰科是一个了不起的线虫群，含有大约600种标称根外寄生物种，其中许多物种被认为是重要的农业害虫。引人注目的是，我们基于18S的系统发育分析，28SrRNA的D2-D3，和Croponematid物种的COImtDNA序列，树拓扑测试（SH和AU测试）支持，透露几乎所有研究过的属，包括Criconema,Ogma,Crossonema,盘形,Hemicrconemoides,Crucoemoides,中胚层，和Lobocriconema,不是单系群体，这一发现与以前对这些群体的研究部分相反。我们的结果表明，用于龟裂科分类的关键形态特征是趋同进化的结果。从我们的研究中可以清楚地看出，必须修改或重新考虑来自GenBank的至少40个共生体物种序列的物种状况，基于多相方法的分析，包括不同的基于树和距离的分子物种定界方法(bPTP，GMYC,ABGD1和ABGD2)。我们的研究发现，自动条形码方法的ABGD2输出与已建立的物种定界非常吻合，而在一般情况下,与最初考虑的物种相比，对应于三个条形码区域的四个物种划界结果提出的推定物种明显更多。这项研究还首次描述了与越南人参相关的刺五加虫和恒阳盘菌的种群，世界上最珍贵、最稀有的人参品种之一。尽管这些种群在形态上与木耳和恒松加的原始描述一致，与存放在GenBank中的序列相比，它们的分子数据显示出明显的差异。这些物种清楚地证明了在Criconematidae家族的几种物种中可以观察到的巨大分子变异。
