The genus Podaxis in arid regions of Mexico: preliminary ITS phylogeny and ethnomycological use

Abstract

Identification of Podaxis species to species-level based on morphology alone is problematic. Thus, species of the genus Podaxis are in dire need of taxonomic and phylogenetic evaluations using molecular data to develop a consensus between morphological taxonomy and more robust molecular analyses. In Mexico, most of the collected specimens of Podaxis have been morphologically identified as Podaxis pistillaris sensu lato and are locally used for its culinary value. In this study, the internal transcribed spacer region of Podaxis specimens from the MEXU fungarium collected between 1948 and 2014 from arid regions of Mexico were sequenced and these collections placed into a molecular phylogenetic framework using Maximum Likelihood analysis. In addition, the ethnomycological use of Podaxis in Mexico (utility, traditional handling, economic importance, etc.) is described by observations, interviews, and sampling of Podaxis species with local people from three areas of the region of the Cañada of Oaxaca, which belongs to the Tehuacán-Cuicatlán Biosphere Reserve. These results indicate that the Mexican Podaxis were divided into two clades. Specimens collected in the northern region showed phylogenetic affinities to clade D, while specimens from the south of Mexico clustered within clade E. Morphological data, such as spore length and width, showed significant differences between the two phylogenetic clades, implying that these clades represent different species. None of the Mexican specimens were found in association with termite mounds, which might indicate an adaptation to desert-like regions. This study provides the first ethnomycological use of Podaxis from Mexico.