Palaeobiogeology-Palaeobotany-Palaeopalynology, UR Geology, University of Liège, Liège, Belgium.
CNRS, University of Lille, UMR 8198 - Evo-Eco-Paleo, Lille, France.
PLoS One. 2018 Jul 11;13(7):e0198287. doi: 10.1371/journal.pone.0198287. eCollection 2018.
Lycopsids are a minor component of current terrestrial herbaceous floras. However, lycopsid fossil diversity shows a great diversity and disparity including heterosporous woody plants, e.g. the giant isoetaleans that populated the extensive Pennsylvanian wetlands. The earliest known isoetaleans come from late Devonian localities from China. Here, we describe Lilingostrobus chaloneri gen. et sp. nov., a new isoetalean lycopsid from the Upper Devonian (Famennian) Xikuangshan Formation of China (Hunan Province, South China), which adds to the already impressive diversity of the Devonian lycopsids from China. Lilingostrobus shows an unusual combination of characters. This new plant is pseudoherbaceous, with a possible tufted habit, and consists of narrow axes with rare isotomies. The stem includes small quantities of secondary xylem. Each fertile axis bears one terminal strobilus comprising sporophylls ending in a very long upturned lamina. Microspores and putative megaspores have been found, but whether the plant has mono- or bisporangiate strobili is unknown. Importantly, our cladistic analysis identifies Lilingostrobus as a direct precursor of Isoetales, which provides new insights into the early evolution of lycopsids.
木贼类植物是现代陆生草本植物区系的一个小组成部分。然而，木贼类植物化石的多样性显示出极大的多样性和差异，包括异孢木质植物，例如在广泛的宾夕法尼亚纪湿地中繁衍生息的巨型工蕨类植物。最早为人所知的工蕨类植物来自中国晚泥盆世的地方。在这里，我们描述了一种新的异孢木质木贼类植物——来自中国上泥盆统（法门阶）锡矿山组的笠鳞木属（Lilingostrobus chaloneri），这增加了中国泥盆纪木贼类植物已经令人印象深刻的多样性。笠鳞木显示出一种不寻常的组合特征。这种新植物是拟草本植物，可能具有丛生习性，由狭窄的轴组成，很少有等二歧。茎包括少量的次生木质部。每个可育轴都有一个终端的球果，由末端具长而向上弯曲的叶的孢子叶组成。已经发现了小孢子和可能的大孢子，但该植物是否具有单或双孢子囊的球果尚不清楚。重要的是，我们的系统发育分析将笠鳞木鉴定为工蕨类的直接祖先，这为木贼类植物的早期进化提供了新的见解。
