Roets Francois, de Beer Z Wilhelm, Wingfield Michael J, Crous Pedro W, Dreyer Léanne L
Department of Botany and Zoology, Stellenbosch University, Stellenbosch 7600, South Africa.
Mycologia. 2008 May-Jun;100(3):496-510. doi: 10.3852/07-181r.
Ophiostoma (Ophiostomatales) represents a large genus of fungi mainly known from associations with bark beetles (Curculionidae: Scolytinae) infesting conifers in the northern hemisphere. Few southern hemisphere native species are known, and the five species that consistently occur in the infructescences of Protea spp. in South Africa are ecologically unusual. Little is known about the vectors of Ophiostoma spp. from Protea infructescences, however recent studies have considered the possible role of insects and mites in the distribution of these exceptional fungi. In this study we describe a new species of Ophiostoma and a new Sporothrix spp. with affinities to Ophiostoma, both initially isolated from mites associated with Protea spp. They are described as Ophiostoma gemellus sp. nov. and Sporothrix variecibatus sp. nov. based on their morphology and comparisons of DNA sequence data of the 28S ribosomal, beta-tubulin and internal transcribed spacer (ITS1, 5.8S, ITS2) regions. DNA sequences of S. variecibatus were identical to those of a Sporothrix isolate obtained from Eucalyptus leaf litter in the same area in which S. variecibatus occurs in Protea infructescences. Results of this study add evidence to the view that mites are the vectors of Ophiostoma spp. that colonize Protea infructescences. They also show that DNA sequence comparisons are likely to reveal additional cryptic species of Ophiostoma in this unusual niche.
长喙壳属(长喙壳目)是一类大型真菌,主要存在于与北半球侵害针叶树的树皮甲虫(象甲科:小蠹亚科)的共生关系中。已知的南半球本土物种很少,而在南非山龙眼属植物的果序中持续出现的五个物种在生态上并不寻常。关于山龙眼属果序上长喙壳属物种的传播媒介知之甚少,不过最近的研究考虑了昆虫和螨类在这些特殊真菌分布中的可能作用。在本研究中,我们描述了一种新的长喙壳属物种和一种与长喙壳属有亲缘关系的新的孢子丝菌属物种,它们最初都是从与山龙眼属植物相关的螨类中分离出来的。根据它们的形态以及28S核糖体、β-微管蛋白和内部转录间隔区(ITS1、5.8S、ITS2)区域的DNA序列数据比较,将它们分别描述为新种双生长喙壳菌(Ophiostoma gemellus sp. nov.)和新种杂色孢子丝菌(Sporothrix variecibatus sp. nov.)。杂色孢子丝菌的DNA序列与在同一地区从桉树叶凋落物中获得的一种孢子丝菌分离株的序列相同,该地区也是杂色孢子丝菌在山龙眼属果序中出现的地方。本研究结果为螨类是在山龙眼属果序上定殖生长的长喙壳属物种的传播媒介这一观点提供了证据。它们还表明,DNA序列比较可能会揭示出这个特殊生态位中更多未被发现的长喙壳属隐性物种。