Unraveling the taxonomic knot of the monospecific Manihot anomala (Euphorbiaceae, Crotonoideae) complex through an integrative systematic approach

Abstract This work aims to review the monospecific Manihot anomala complex through an integrative approach that involves leaf morphometry, descriptive taxonomy, and ecological analysis. Four subspecies, as well as M. warmingii , are here synonymized under M. anomala as result of overlapping diagnostic characters and geographic distribution. Two leaf morphotypes stood out in the complex, but these could not be recognized at the species or subspecies level, as their morphological differences can likely be attributed to hybridization and recent adaptation to contrasting environmental conditions. Among the three tested environmental variables, precipitation was the most relevant, with statistically significant values for six of 12 morphological characters. We also found that the reproductive characters traditionally used to delimit subspecies of M. anomala are unreliable and of limited taxonomic value for infraspecific delimitation, due to their high variability, developmental instability, and extensive overlap among taxa. Finally, a treatment for M. anomala is provided, containing descriptive analysis, taxonomic decisions, and occurrence update, in addition to six lectotypifications. The present work helps to resolve the status of M. anomala , while providing tools for future studies involving both Manihot and other plant groups known for their high foliar plasticity.