Leaves of Podozamites and Pseudotorellia from the Early Cretaceous of Mongolia: stomatal patterns and implications for relationships
Leaves of Podozamites and Pseudotorellia from the Early Cretaceous of Mongolia: stomatal patterns and implications for relationships
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DOI：
10.1080/14772019.2016.1274343
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发表时间：
2018-01
影响因子：
2.6
通讯作者：
G. Shi;Fabiany Herrera;P. Herendeen;A. Leslie;N. Ichinnorov;Masamichi Takahashi;P. Crane
中科院分区：
文献类型：
--
作者：
G. Shi;Fabiany Herrera;P. Herendeen;A. Leslie;N. Ichinnorov;Masamichi Takahashi;P. Crane
Podozamites和Pseudotorellia的带状平行脉叶是北方半球晚三叠世至早白垩世植物群中最常见的化石之一。Podozamites被认为是voltzian针叶树的叶子，但其角质层知之甚少，而具有厚角质层和单唇气孔的Pseudotorellia通常被认为是银杏的叶子。本文根据蒙古中部早白垩世保存良好的材料，描述了Podozamites和Pseudotorellia的叶形态、角质层和气孔。具横向排列的平列型（可能为合唇型）气孔，气孔呈纵列规则排列。新种Pseudotorellia resinosa sp. nov.和Pseudotorellia palustris sp. nov.气孔分布分散，具纵向排列，两个保卫细胞凹陷，被2-5个特化的侧附属细胞和1-3个非特化的极细胞包围。相关证据和表皮结构的相似性表明，Podozamites harrisii是由相同的植物产生的种子锥Krassilovia。Podozamites harrisii和Krassilovia的独特气孔模式也出现在Swedenborgia和Cycadocarpidium的一些物种中，这表明这些植物可能都属于同一个自然群。Cycadocarpidium、Krassilovia和Swedenborgia以前被认为是针叶树，但它们的横向排列的平列气孔暗示了它们与Bennettitales和Gnetales的可能关系。
Strap-shaped, parallel-veined leaves of Podozamites and Pseudotorellia are among the most common fossils in Late Triassic to Early Cretaceous floras from the Northern Hemisphere. Podozamites is considered to be the leaf of a voltzian conifer, but its cuticle is poorly known, whereas Pseudotorellia, with a thick cuticle and haplocheilic stomata, is commonly considered to be the leaf of a ginkgoalean. Here we describe the leaf morphology, cuticle and stomata of Podozamites and Pseudotorellia based on excellently preserved material from the Early Cretaceous of central Mongolia. Podozamites harrisii sp. nov. has transversely oriented, paracytic (probably syndetocheilic) stomata that are regularly arranged in longitudinal files. Pseudotorellia resinosa sp. nov. and Pseudotorellia palustris sp. nov. have scattered, longitudinally oriented stomata in which the two guard cells are sunken and surrounded by 2–5 specialized lateral subsidiary cells and 1–3 unspecialized polar cells. Association evidence and similarities in cuticular structure suggest that Podozamites harrisii was produced by the same plant as the seed cone Krassilovia. The distinctive stomatal pattern of Podozamites harrisii and Krassilovia is also seen in some species of Swedenborgia and Cycadocarpidium, suggesting these plants may all belong to the same natural group. Cycadocarpidium, Krassilovia and Swedenborgia have previously been treated as conifers, but their transversely oriented, paracytic stomata hint instead at a possible relationship with Bennettitales and Gnetales.