Latest Permian acritarchs from South China and the Micrhystridium/Veryhachium complex revisited

Abstract

Diverse and well-preserved latest Permian phytoplankton assemblages are described from four sections of the Yangtze Block, South China from localities in Zhongzhai (Guizhou Province), Shangsi (Sichuan Province), Xiakou (Hubei Province) and Dongpan (Guangxi Province). Most of the species have been reported previously from other upper Permian sections worldwide. The South Chinese phytoplankton taxa are generally very small in size, usually displaying diameters of about 20 μm and commonly include the genera Micrhystridium, Veryhachium and Leiosphaeridia. However, larger taxa with vesicles often exceeding 80 μm in diameter, such as Dictyotidium, are also abundant in the Shangsi section. Due to the presence of large populations of Micrhystridium and Veryhachium, a simple classification scheme for the Micrhystridium/Veryhachium complex is proposed, based on the geometrical shape of the vesicle. We propose dividing the complex into five groups: the Veryhachium cylindricum group, representing all ellipsoidal specimens; the Veryhachium trispinosum group, all with triangular-shaped vesicles; the Veryhachium lairdii group, all with rectangular forms; the Micrhystridium pentagonale group, all with pentagonal specimens; and the Micrhystridium breve group, which includes all spherical forms.

Keywords:

• phytoplankton
• Micrhystridium/Veryhachium complex
• Late Permian
• Yangtze Block
• China

Acknowledgements

We express sincere thanks to Hu Qing, Zhang Lei, Liu Guichun, Shen Jun, Xiang Yu, and Miss Xu Guozhen and Nie Xiaomei for their help with the fieldwork. We acknowledge the two referees (Reed Wicander, Central Michigan University, USA, and Clinton Foster, Geoscience Australia) for their detailed reviews and helpful comments, and the Editor of the journal, Jim Riding (British Geological Survey), for his help and advice. This work was supported by National Science Foundation of China (NSFC) Project numbers 40839903, 40921062, the Chinese 973 (2011CB808800), and 111 programmes (B08030), the Ministry of Education of China (NCET-10-0712), the Fundamental Funds for the Central Universities (CUGL100504), the Foundation of the Geological Survey of China (1212011220529), and by grants of the University of Lille1 (‘Allocation Présidentielle’ and ‘Bonus Qualité Recherche’) and the Conseil Régional du Nord (France).