Original paper

Siliceous microfossils (Bacillariophyceae, Chrysophyceae) from the Upper Lerma Basin, Mexico

Valadez, Francisco; Caballero, Margarita; Rodríguez-Vargas, DeníClaudia Sugiura-Yamamoto

Abstract

Siliceous remains (diatoms and Chrysophyte stomatocysts) from the lacustrine sediments of lake Chignahuapan, Upper Lerma Basin, are illustrated and briefly described. The diatom record from these sediments has been used for palaeolimnological reconstruction (published in earlier papers) of the evolution of this lake during the last ca. 22,000 yrs and, particularly, of the correlation of lake level fluctuations with human occupation during the late Classic and Epiclassic periods (AD 600-900). The diatom flora present in these sediments is rich in terms of species and varieties, with a total of 44 identified taxa. Genera such as Fragilaria Lynbye, Achnanthes Bory, Navicula Bory, Nitzschia Hassall, Cymbella C. A. Agardh, Pinnularia Ehrenberg, Eunotia Ehrenberg and Gomphonema Ehrenberg showed the highest species diversity. Chrysophyte cysts were present in low numbers and five types are described and illustrated.

Keywords

mexicodiatomchrysophycean cyst