Cuticular morphology of <i>Schinus</i> L. and related genera

Abstract The Anacardiaceae are a characteristic angiosperm family of the Neotropics where they comprise ~32 genera and 200 species (~80 genera and 800 species globally). Among Neotropical Anacardiaceae genera, Schinus has the greatest species richness with 42 species distributed from tropical latitudes of Brazil and Peru south to the temperate steppe, matorral, and Valdivian temperate forest communities of Patagonia. Previous studies have found some anatomical and morphological leaf traits (e.g. simple vs. compound leaf organization) useful in characterizing lineages within Schinus, but also document traits that are homoplastic within the genus (e.g. stomatal distribution) and convergent among Schinus and its close relatives Lithrea and Mauria (e.g. mesophyll arrangement). Here, we present a survey of leaf cuticular traits in 53 species of Schinus and its closest relatives Lithrea, Mauria, and Euroschinus based on characters observed with scanning electron and optical light microscopy. We use ordinated Bray–Curtis distances based on 18 characters and 2D nonmetric multidimensional scaling to show that cuticular morphology resolves the three most diverse genera, Euroschinus, Mauria, and Schinus, but does not resolve intrageneric sections of Schinus. We propose that a distinctive acuminate gland type occurring only within Euroschinus may constitute a potential synapomorphy for this genus. Within Schinus, we find inconsistency in stomatal distribution among specimens of a single species, among species of a single section, and between sections of the genus, and suggest that current evidence is insufficient to implicate either phenotypic plasticity or homoplasy as the causative mechanism of this variation.