Background and Aims The three relict genera Pherosphaera, Microcachrys and Saxegothaea in Podocarpaceae produce quite distinct seed cone types in comparison with other genera and do not form a clade along with Acmopyle. The detailed seed cone morpho-anatomy of these three relict genera and affinities with other podocarps are poorly known. This study aims to understand the seed cone morpho-anatomy and affinities among these three disjunct relict genera and with other podocarps. Methods We comparatively analysed the seed cone morpho-anatomical traits of the three podocarps genera and used ancestral state reconstruction to understand the evolution of these traits. Key Results We described the seed cone morpho-anatomical structures of the three relict genera in detail. The three genera produce aggregated multiovulate cones. Both Microcachrys and Saxegothaea have an asymmetrical free cup-like epimatium. Both species of Pherosphaera lack an epimatium. The ancestral state reconstruction implies that the presence of an epimatium is an ancestral trait in podocarps and is independently lost in Pherosphaera and Phyllocladus. The seed cones are fleshy in Microcachrys and non-fleshy in Saxegothaea and Pherosphaera. The seed cone macrofossils of both extinct and living podocarps also show the presence of an epimatium and fleshiness in podocarps. Conclusions Altogether, the morpho-anatomy suggests that Pherosphaera, Microcachrys and Saxegothaea present affinities with each other and other podocarps, but the reconstruction of the ancestral seed cone in Podcarpaceae is quite complex due to multiple convergent evolutions of several structures. These structures (e.g. epimatium, aril and receptaculum) are of low taxonomic value but of great evolutionary and ecological significance, and are responsive adaptations to ever-changing environmental conditions.

中文翻译：

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基于籽锥性状的三个古特有罗汉松属的形态解剖亲缘关系和进化关系


背景和目的罗汉松科中的三个孑遗属Pherosphaera、Microcachrys 和Saxegothaea 与其他属相比产生了截然不同的种子球果类型，并且不与Acmopyle 一起形成分支。这三个孑遗属的详细种子锥形态解剖学以及与其他罗汉松的亲缘关系鲜为人知。本研究旨在了解这三个分离的孑遗属以及与其他罗汉松属之间的种子锥形态解剖结构和亲缘关系。方法比较分析三个罗汉松属的种子球形态解剖特征，并利用祖先状态重建来了解这些性状的演化。主要结果 我们详细描述了三个孑遗属的种子锥形态解剖结构。这三个属产生聚集的多卵球果。 Microcachrys 和 Saxegothaea 都有不对称的游离杯状外皮。两种Pherosphaera 物种均缺乏epimatium。祖先状态重建意味着，epimatium 的存在是罗汉松的祖先特征，并且在 Pherosphaera 和 Phyllocladus 中独立丢失。 Microcachrys 的球果是肉质的，而 Saxegothaea 和 Phorosphaera 的球果是非肉质的。已灭绝和现存罗汉松的种子锥大化石也显示出罗汉松中存在外皮和肉质。结论 总而言之，形态解剖学表明，Pherosphaera、Microcachrys 和 Saxegothaea 彼此之间以及其他罗汉松类植物之间存在亲缘关系，但由于几种结构的多重趋同进化，罗汉松科祖先种子锥的重建相当复杂。这些结构（例如 Epimatium、aril 和 receptaculum）的分类学价值较低，但具有重大的进化和生态意义，并且是对不断变化的环境条件的响应性适应。