Leaf Structure of Microlicieae (Melastomataceae): Taxonomic and Adaptive Implications

Abstract

Abstract—Microlicieae is a Neotropical tribe of Melastomataceae, and most of its species are endemic to Brazil, especially in campo rupestre sites. The campo rupestre ecosystem occurs in areas with shallow soils deficient in water and nutrients, and elevations above 900 m. Foliar characters provide important structural features which are of taxonomic value for Melastomataceae. Due to the high degree of endemism, taxonomic issues, and variety of water economy strategies found in Melastomataceae, our objective was to evaluate the leaf structure in 25 species of Microlicieae, aiming to identify potentially taxonomically informative characters which may have favored the radiation and diversification of this tribe. According to our results, Lavoisiera seems to be homogeneous regarding leaf characters, while Microlicia and Trembleya are highly variable in leaf size and general structure of veins and mesophyll. The leaf xeromorphism was presumably a relevant factor in the diversification of this tribe. Rhynchantera exhibited mesomorphic leaf characters, suggesting that the emergence of these features occurred after the divergence of this group from the rest of the clade.