ABSTRACT Acrospermum is a poorly known genus of epibiotic and saprophytic species with a subcosmopolitan distribution. Here, we investigate the intriguing relationship between Acrospermum and its host plants in the fern family Polypodiaceae, where it occurs upon approximately 45 neotropical species. We conducted phylogenetic analyses using an eight-marker comprehensive ascomycete data set comprising 719 species representing all major lineages along with 23 new Acrospermum specimens sampled from ferns. We ask whether fern-dwelling Acrospermum are monophyletic, whether epibiotic Acrospermum have evolved independently from saprophytic ancestors, and identify anamorphic phases by incorporating sequences for all suspected taxa. Our results corroborate the placement of Acrospermales within the Dothideomycetes with strong support. However, the order remains incertae sedis due to weak support along the branches subtending the clade that includes the Acrospermales plus Dyfrolomycetales. Our results show a strong phylogenetic pattern in lifestyles but do not clearly identify an ancestral life history state. The first divergence in Acrospermaceae splits fungicolous taxa from taxa that inhabit plants; saprophytes and anamorphic phases found on angiosperms occur in both clades. Fungicolous species are monophyletic, whereas species with an epibiotic or necrotic life history upon plants are nonmonophyletic due to the position of the saprophyte A. longisporium. Previously, all Acrospermum collected from ferns were identified as A. maxonii. Our results indicate that this is not monophyletic due to the inclusion of Gonatophragmium triuniae. Two species are described herein as A. gorditum, sp. nov., and A. leucocephalum, sp. nov. We find no instances of co-cladogenesis; however, our ability to detect this is limited by the lack of resolution in the A. maxonii clade. Rather, we see that that the distribution of epibiotic Acrospermum is explained by the overlap between the ecological niche of the Acrospermum species and its host.

中文翻译：

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天顶花科的多位点系统发育：新的外生物种和生殖器、假处女座和无定形褐指菌的位置

摘要 Acrospermum 是一种鲜为人知的附生和腐生物种，具有亚世界性分布。在这里，我们调查了顶叶植物与其宿主植物在蕨类植物 Polypodiaceae 之间的有趣关系，它发生在大约 45 种新热带物种上。我们使用包含代表所有主要谱系的 719 个物种以及从蕨类植物中取样的 23 个新的顶叶植物标本的八标记综合子囊菌数据集进行系统发育分析。我们询问生活在蕨类植物中的 Acrospermum 是否是单系的，附生的 Acrospermum 是否独立于腐生祖先进化而来，并通过整合所有可疑分类群的序列来识别变形阶段。我们的结果证实了在 Dothideomycetes 中的 Acrospermales 的位置，并得到了强有力的支持。然而，由于沿着分支对着包括 Acrospermales 和 Dyfrolomycetales 的进化枝的弱支持，该目仍然是 incertae sedis。我们的结果显示了生活方式的强烈系统发育模式，但没有清楚地确定祖先的生活史状态。Acrospermaceae 的第一次分化是将真菌类群与植物中的类群分开；在被子植物上发现的腐生植物和变形相出现在两个进化枝中。真菌物种是单系的，而在植物上具有附生或坏死生活史的物种是非单系的，这是由于腐生 A. longisporium 的位置。以前，从蕨类植物中收集的所有 Acrospermum 都被确定为 A. maxonii。我们的结果表明，由于包含 Gonatophragmium triuniae，这不是单系的。两个物种在本文中被描述为 A. gorditum, sp。11 月，和 A. leucocephalum，sp。十一月 我们没有发现共枝发生的实例；然而，我们检测到这一点的能力受到 A. maxonii 进化枝缺乏分辨率的限制。相反，我们看到附生顶叶植物的分布是由顶叶植物物种的生态位与其宿主之间的重叠所解释的。