Molecular and morphological data support the recognition of a new species of Otatea (Poaceae: Bambusoideae: Guaduinae) from Durango, Mexico

Otatea is the second-largest genus in subtribe Guaduinae, Bambuseae tribe of subfamily Bambusoideae (Poaceae) and has its geographical distribution in Mexico, El Salvador and Colombia. Ten of its 12 species are endemic to Mexico. The species with the most widespread geographical distribution in Mexico is Otatea acuminata. Recent fieldwork in the Mexican state of Durango found a flowering population of Otatea aff. acuminata, which sparked further investigation of the species. Previous molecular and morphological analyses indicated that O. acuminata is a polyphyletic species. Our aim was to delimit the species of the Otatea acuminata species complex using molecular and morphological data in a phylogenetic framework and applying parametric species delimitation methods. To this end we used both chloroplast and nuclear sequence data in combination with morphological characters to conduct phylogenetic and species delimitation analyses. Our phylogenetic and species delimitation results indicate that the former O. acuminata population of Durango is a distinct species. Collected flowering plants allowed us to prepare a complete description of the new species, which we have named O. odam. With the description of this new species, the number of Otatea species endemic to Mexico increases to 11. Otatea odam sp. nov. inhabits the ecotone between tropical dry forest and xerophilous scrub of the Madrean, Madrean Xerophilous and Tropical ecoregions of the Sierra Madre Occidental, suggesting that this species is a drought-tolerant woody bamboo.