<i>Fusarium</i> species associated with <i>Euwallacea xanthopus</i> in South Africa, including two novel species
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Ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are small wood-boring insects that live in an obligate symbiosis with fungi, which serve as their primary food source. Beetles residing in the genus <i>Euwallacea</i> have evolved a unique association with a clade of <i>Fusarium</i> that falls within the aptly named Ambrosia <i>Fusarium</i> Clade (AFC). The discovery of the invasive polyphagous shot hole borer, <i>E. fornicatus</i>, in South Africa, has heightened awareness of ambrosia beetles and their symbionts in the country. In this study, we investigated the <i>Fusarium</i> symbionts of three species of <i>Euwallacea</i> in South Africa, with a specific focus on those associated with <i>E. xanthopus</i>. Isolations of <i>Fusarium</i> strains from both living and dissected beetles yielded nearly 100 isolates. Using multigene phylogenetic analyses, these isolates were identified as six different <i>Fusarium</i> species. <i>Fusarium hypothenemi</i> and <i>F. euwallaceae</i> have previously been reported from South Africa. <i>Fusarium pseudensiforme</i> and <i>Fusarium</i> AF-6 are new records for the country. The remaining two species are new to science and are described here as <i>F. rufum</i> sp. nov. and <i>F. floriferum</i> sp. nov. Targeted fungal isolation from specific beetle body parts revealed that the AFC species collected were typically associated with the dissected beetle heads and helped us identify the likely nutritional symbiont of <i>E. xanthopus</i>. This study highlights the understudied diversity of fungal associates of ambrosia beetles present in South Africa.
食菌小蠹（Ambrosia beetles）是一类小型蛀木昆虫，隶属于鞘翅目（Coleoptera）、象甲科（Curculionidae）、小蠹亚科（Scolytinae），与真菌形成专性共生关系，真菌为其主要食物来源。Euwallacea属（Euwallacea）昆虫与隶属于食菌镰刀菌演化支（Ambrosia Fusarium Clade，AFC）下的镰刀菌属（Fusarium）类群形成了独特的共生关系。入侵性多食性射孔小蠹（Euwallacea fornicatus，E. fornicatus）在南非被发现后，提升了该国对食菌小蠹及其共生体的关注度。本研究针对南非的3种Euwallacea属（Euwallacea）昆虫的镰刀菌属（Fusarium）共生体，重点关注与E. xanthopus相关的共生体。从活虫及解剖后的小蠹虫体内分离得到的镰刀菌菌株共计近100株。通过多基因系统发育分析，这些分离株被鉴定为6个不同的镰刀菌属（Fusarium）物种。Fusarium hypothenemi（Fusarium hypothenemi）和F. euwallaceae（F. euwallaceae）此前已在南非有报道。Fusarium pseudensiforme（Fusarium pseudensiforme）和Fusarium AF-6（Fusarium AF-6）为南非新记录物种。其余2个物种为科学界新发现物种，本文将其正式描述为F. rufum sp. nov.和F. floriferum sp. nov.（均为新种）。针对小蠹虫特定身体部位的靶向真菌分离实验显示，所采集的AFC类群真菌通常与解剖后的小蠹虫头部相关联，并帮助我们确定了E. xanthopus潜在的营养共生体。本研究凸显了南非境内食菌小蠹真菌共生伙伴多样性的研究不足现状。
