含亚洲、欧洲、北美洲山毛榉病害病原菌的Neonectria coccinea复合群的物种概念

Species delimitation for Neonectria coccinea group including the causal agents of beech bark disease in Asia,Europe,and North America

对包含亚洲、欧洲、北美洲山毛榉病害病原菌在内的Neonectria coccinea复合群中物种之间的系统演化关系以及物种概念进行了探讨。Neonectria faginata(曾处理为Neo.coccinea var.faginata)与狭义的Neo.coccinea和Neo.punicea有明显区别。系统树显示5个分支与Neo.coccinea群的关系较为接近,由于缺乏显著的形态差异,它们始终没有在物种的等级上区分。根据形态学、系统发育、寄主专化性和地理因素,采用多基因act、ITS、LSU、rpb1、tef1和tub序列分析的方法,对亚洲、欧洲、北美洲的相关材料进行了研究,结果表明,它们代表4个独立的物种,即Neo.coccinea,Neo.faginata,Neo.microconidia和Neo.punicea,对每个种进行了详尽的描述和图示。并为Sphaeria coccinea和Neonectria coccinea var.faginata指定了附加模式。

Neonectria coccinea has historically been known as a serious pathogen of beech trees in North America and Europe. Phylogenetic relationships of this species and its relatives have been determined. Neonectria faginata, previously referred to as Neo. coccinea var. faginata has been delimited from Neo. coccinea sensu stricto and Neo. punicea. Five additional lineages supported by relatively high phylogenetic values are allied with Neo. coccinea and its relatives. Until now, these lineages have not been recognized as species because no significant morphological differences among them were found. Although each phylogenetic species appeared to be unique in host specificity and geography, relatively few specimens of these species existed. We re-evaluated these species using newly obtained specimens and isolates from Asia, Europe, and North America. Based on sequences of multiple loci, specifically act, ITS, LSU, rpb1, tef1 and tub, our results indicate that these isolates represent four phylogenetic species, Neo. coccinea, Neo. faginata, Neo. microconidia, and Neo. punicea. In our phylogeny, each species is well supported by high BI PP, MP BP, and ML BP values. The single-locus analyses of ITS and LSU did not correlate with our species recognition criteria. Based on morphology, phylogeny, host specificity and geographical traits, these four species are conclusively delimited. Each of them is re-described and illustrated. Epitype specimens for Sphaeria coccinea and Neonectria coccinea var. faginata are designated. Because no type specimen of Neo. punicea was found, this name is neotypified. Within Neo. coccinea, Neo. microconidia, and Neo. punicea, some sublineages were supported by high phylogenetic values. In the future these may warrant recognition as distinct species.