中国科学院南京地质古生物研究所机构知识库

The genus Asterotheca is a representative marattialean fern of reproductive organs associated with Pecopteris fronds in the Late Paleozoic. The species of Asterotheca orientalis (Schenk) Potonie has a wide distribution in East-ern Asia, and for a long time it has been regarded as an index fossil of the Early Permian floras in North China. However, the detailed structures of sporangia and in situ spores for A. orientalis were poorly understood. In this study, exceptionally well-preserved fertile specimens of A. orientalis from the Lower Permian Kaipaicileike For-mation in the Tarim Basin, Xinjiang, northwestern China, were investigated based on the studies on the material using light and scanning electron microscopies. Fertile pinnules are morphologically similar to sterile ones but bear Asterotheca-type synangia. Each synangium consists of a ring of 4-6 sporangia. The spores are trilete, with circular to subcircular amb, diameter of ca. 40 mu m, and granulate sculpture. Comparisons were made between A. orientalis spores and those of other related in situ spores, as well as dispersed spores based on morphological and microstructural evidence. The dispersed spore species of Cyclogranisporites minutus (Bharadwaj)share the closest similarities in both the shape and size with in situ spores of A. orientalis. The present observations on the fertile organs of A. orientalis enrich diversity of the Asterotheca in situ spores, and provide clues for further understanding on the systematics and evolution of marattialean plants fen linage.(c) 2022 Elsevier B.V. All rights reserved.