Premise of research. The Puddledock mesofossil flora from Virginia is the richest source for studying structurally preserved plant fossils in the Early Cretaceous Potomac Group sequence. Together with other mesofossil floras from the Potomac Group and also from Portugal, it is key for direct assessment of the structure, relationships, and reproductive biology of early angiosperms. In this study, a new multiparted floral structure from the Puddledock locality is analyzed, and its phylogenetic relationships are discussed. Methodology. The fossil was extracted from unconsolidated clays and sands through sieving in water. Adhering sediment was removed using HF and HCl followed by rinsing in water. External and internal features were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy. Phylogenetic analyses were carried out by adding the features of the fossil flower to an existing morphological data set for extant angiosperms. Pivotal results. A new taxon, Melloniflora virginiensis gen. et sp. nov., is established on the basis of a small multiparted floral structure that has several series of free stamens (ca. 50) and carpels (21) borne on a flattened receptacle. Stamens have a broad, short base, and dehiscence is introrse. Ovules are borne in two rows on either side of the ventral suture of the carpels. Abundant secretory cells occur in all tissues. Melloniflora is related to extant early-diverging members of the Magnoliales but also has features found among extant taxa of other early-diverging angiosperm lineages such as Austrobaileyales. Conclusions. Melloniflora adds to the knowledge of plants related to extinct magnoliids from the Early Cretaceous. It shows a combination of features not seen in any extant taxon. Melloniflora contributes to the evidence of considerable extinct diversity at an early stage in angiosperm evolution, especially among clades that today are represented by only a few relatively species-poor lineages.

中文翻译：

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Melloniflora，一种来自美国弗吉尼亚州早白垩世的已灭绝的新多裂花

研究的前提。来自弗吉尼亚州的 Puddledock 中化石植物群是研究早白垩世波托马克群序列中结构保存的植物化石的最丰富的来源。与来自波托马克集团和葡萄牙的其他中化石群一起，它是直接评估早期被子植物的结构、关系和生殖生物学的关键。在这项研究中，分析了来自 Puddledock 地区的一种新的多部分花结构，并讨论了其系统发育关系。方法。化石是通过在水中筛分从松散的粘土和沙子中提取的。使用 HF 和 HCl 去除粘附的沉积物，然后用水冲洗。使用扫描电子显微镜和同步辐射 X 射线断层扫描显微镜研究外部和内部特征。通过将化石花的特征添加到现存被子植物的现有形态学数据集中进行系统发育分析。关键结果。一个新的分类群， Melloniflora virginiensis gen。等 sp. 11 月，建立在一个小的多部分花结构的基础上，该结构具有几个系列的游离雄蕊（约 50）和心皮（21），位于扁平的花托上。雄蕊具有宽而短的基部，开裂是内向的。胚珠在心皮腹缝的两侧生出两排。丰富的分泌细胞存在于所有组织中。Melloniflora 与 Magnoliales 现存的早期分化成员有关，但也具有在其他早期分化的被子植物谱系（如 Austrobaileyales）的现存分类群中发现的特征。结论。Melloniflora 增加了与早白垩世灭绝木兰科植物相关的知识。它显示了在任何现存分类群中都没有看到的特征组合。Melloniflora 在被子植物进化的早期阶段提供了相当多的灭绝多样性的证据，特别是在今天仅由少数物种相对贫乏的谱系代表的进化枝中。