Montserrath Medina-Acosta,^1,* Rosaura Grether,^1,**,*** Angélica Martínez-Bernal,^1,**** Elia Ramírez-Arriaga<sup>2,*****

1</sup>aLaboratorio de Biosistemática de Leguminosas, Departamento de Biología, División de C.B.S., Univers
²bLaboratorio de Palinología: Paleopalinología y Actuopalinología, Instituto de Geología, Universidad

^*MONTSERRATH MEDINA ACOSTA holds a bachelor's degree and a master's degree in biology issued by the Universidad Autónoma Metropolitana (UAM-Iztapalapa), Mexico. She specialises in palynology of the genus Mimosa and light microscopy, in addition to scanning (SEM) and transmission (TEM) electron microscopy techniques.
^**CONTACT Rosaura Grether rogg@xanum.uam.mx
^***ROSAURA GRETHER, a professor in the Department of Biology, Universidad Autónoma Metropolitana (UAM-Iztapalapa) since 1976, holds a PhD in scienc (biology) from the Faculty of Sciences, UNAM. She founded the Herbario Metropolitano (UAMIZ) and served as its curator from 1981 to 1986. Dr Grether is the founder of a research group on the biosystematics of legumes and her research is focused on the systematics of the legume family, especially in the taxonomy of the genus Mimosa. She has worked on phylogenetic studies of the genus Mimosa and related groups of mimosoids in recent years and also directs comparative studies on wood anatomy and studies of the pollen-stigma relationship and the reproductive biology of the genus Mimosa.
^****ANGÉLICA MARTÍNEZ BERNAL, a professor and researcher in the Universidad Autónoma Metropolitana-Iztapalapa's Department of Biolgy since 1990, completed her master's at the Faculty of Sciences, UNAM. As a member of the research group on the biosystematics of legumes, her lines of research are taxonomy, floristics, systematics and palynology of legumes, particularly of the genus Mimosa. In recent years, she has worked on the vegetation of both semiarid and dry ecosystems.
^*****ELIA RAMÍREZ ARRIAGA is a researcher at the Instituto de Geología, Universidad Nacional Autónoma de México (UNAM). She was awarded a bachelor's degree in biology from UNAM in 1989, has been working at the UNAM since 1992, and earned her PhD in biological sciences (UNAM) in 2005 for research concerning Cenozoic palynostratigraphy. Dr Ramírez currently teaches palynolgy in the UNAM Biological Sciences Postgraduate Program and conducts research on both Cenozoic palynology and actuopalynology. Experienced in working with Paleogene and Neogene palynofloras recovered from south-central continental Mexican palaeobasins and from marine palaeobasins in Baja California Sur, she contributes to the systematic taxonomy of Cenozoic pollen grains and spores, as well as to the study of the Cenozoic evolution of Mexican plant communities, with particular emphasis on semiarid vegetation.