Paisia, an Early Cretaceous eudicot angiosperm flower with pantoporate pollen from Portugal
Paisia, an Early Cretaceous eudicot angiosperm flower with pantoporate pollen from Portugal
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DOI：
10.1080/00173134.2017.1310292
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发表时间：
2018-01-01
期刊：
影响因子：
0.9
通讯作者：
Pedersen, Kaj Raunsgaard
中科院分区：
文献类型：
--
作者：
Friis, Else Marie;Mendes, Mario Miguel;Pedersen, Kaj Raunsgaard
本文描述了采自葡萄牙早白垩世Catefica中化石植物群的一种新被子植物--Paisia pantoporata。花辐射对称，结构两性，单轮有五个肉质花被片，单轮有五个雄蕊，单轮有五个心皮。花被片、雄蕊和心皮对生，排列在相同的半径上，花被片基部内卷，包住雄蕊。雄蕊有一个巨大的花丝，没有关节进入花药。花药二囊，四囊，小花粉囊之间有广泛的药隔组织。花粉粒具泛孔和多刺。心皮离生，表面上是扁平的，许多胚珠沿着腹面边缘着生两排。Paisia pantoporata是已知的最古老的花与pantoporate花粉。类似pantoporate花粉也被确认在相关的分散palynoflora。Paisia被解释为可能是昆虫授粉的草本植物，具有低花粉产生和低花粉传播潜力。Paisia的系统位置不确定，Paisia pantoporata很可能属于一个灭绝的谱系。泛孔花粉分散在被子植物的所有主要类群中，与化石的密切匹配尚未确定。五瓣花的组织与雄蕊，花粉和心皮的结构一起建议系统发育的位置接近早期分歧的真双子叶植物谱系，可能在毛茛目。
A new fossil angiosperm, Paisia pantoporata, is described from the Early Cretaceous Catefica mesofossil flora, Portugal, based on coalified floral buds, flowers and isolated floral structures. The flowers are actinomorphic and structurally bisexual with a single whorl of five fleshy tepals, a single whorl of five stamens and a single whorl of five carpels. Tepals, stamens and carpels are opposite, arranged on the same radii and tepals are involute at the base clasping the stamens. Stamens have a massive filament that grades without a joint into the anther. The anthers are dithecate and tetrasporangiate with extensive connective tissue between the tiny pollen sacs. Pollen grains are pantoporate and spiny. The carpels are free, apparently plicate, with many ovules borne in two rows along the ventral margins. Paisia pantoporata is the oldest known flower with pantoporate pollen. Similar pantoporate pollen was also recognised in the associated dispersed palynoflora. Paisia is interpreted as a possibly insect pollinated, herbaceous plant with low pollen production and low dispersal potential of the pollen. The systematic position of Paisia is uncertain and Paisia pantoporata most likely belongs to an extinct lineage. Pantoporate pollen occurs scattered among all major groups of angiosperms and a close match to the fossils has not been identified. The pentamerous floral organisation together with structure of stamen, pollen and carpel suggests a phylogenetic position close to the early diverging eudicot lineages, probably in the Ranunculales.