Gymnosphaera represents a minor lineage within the scaly tree-fern family Cyatheaceae. Tropical and subtropical mainland Asia is a main distribution area of Gymnosphaera. However, the species diversity of Gymnosphaera is currently incompletely known in mainland Asia due to lacking critical revision. Here we present new findings of species diversity and their relationships to mainland Asian Gymnosphaera based on field surveys, the examination of herbarium collections, and phylogenetic analyses of sequences of multiple chloroplast and nuclear regions. Two new species, G. saxicola from southwestern Yunnan and G. bachmaensis from central Vietnam, are established. Traditionally recognized G. podophylla is revealed to be a complex, from which G. bonii is reinstated as a distinct species. Our phylogenetic analyses identified four clades within Gymnosphaera in mainland Asia: G. denticulata clade, G. gigantea clade, G. podophylla clade, and G. salletii clade. The new species G. saxicola, which is special for its saxicolous habitat, was resolved as sister to G. austroyunnanensis in the G. salletii clade. The newly discovered G. bachmaensis, which is characterized specially by the spathulate frond, was positioned in the G. podophylla clade, being sister to G. bonii. The mountainous region from south-central Vietnam northwards to western Yunnan is a diverse center of Gymnosphaera and more species of this group are probably to be discovered there.

中文翻译：

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对亚洲大陆 Gymnosphaera (Cyatheaceae) 的贡献：两个新物种，Cyathea bonii 的恢复及其系统发育位置

Gymnosphaera代表有鳞的树蕨科 Cyatheaceae 中的一个次要谱系。亚洲热带和亚热带大陆是裸球藻的主要分布区。然而，由于缺乏批判性修订，目前亚洲大陆对Gymnosphaera的物种多样性并不完全了解。在这里，我们基于实地调查、植物标本馆藏品的检查以及多个叶绿体和核区域序列的系统发育分析，介绍了物种多样性及其与亚洲大陆裸球藻的关系的新发现。建立了两个新种，云南西南部的G. saxicola和越南中部的G. bachmaensis 。传统上认可G. podophylla被发现是一个复合体，从中G. bonii被恢复为一个独特的物种。我们的系统发育分析确定了亚洲大陆 Gymnosphaera 的四个进化枝： G . denticulata进化枝、G. gigantea进化枝、G. podophylla进化枝和G. salletii进化枝。新种G. saxicola因其栖息地的特殊性，在G. salletii进化枝中被确定为G. austroyunnanensis的姐妹。新发现的G. bachmaensis，其特征是具有特殊的匙形叶，位于G. podophylla进化枝，是G. bonii的姐妹。从越南中南部向北到云南西部的山区是一个多样化的裸球体中心，可能会在那里发现更多该组的物种。