ANATOMIA COMPARATIVA DE FOLÍOLOS DE Machaerium Pers. (LEGUMINOSAE – PAPILIONOIDEAE – DALBERGIEAE): CONTRIBUIÇÕES À SISTEMÁTICA

Abstract

Machaerium, a predominantly Neotropical genus, aggregates 130 species, with 44 of them endemic to Brazil. Several taxonomic and phylogenetic studies have been conducted on the infrageneric circumscription of Machaerium, verifying overlaps in the morphological characters that delimit each section and proposing the dismemberment of the sections traditionally recognized in Machaerium, prompting further investigations on its morphological delimitation. Our objectives were to realize a comparative analysis of morphological and anatomical features from the leaflets of Machaerium relevant to systematics, to assess the occurrence of secretory structures, evaluating their type, location and nature of their exudates, and to evaluate the monophyletism and potential synapomorphies for the Lineata clade. We performed internal and external morphological investigations on leaflets of 20% of the species of Machaerium using light microscopy and scanning electron microscopy techniques. We performed phylogenetic analyses with matK marker and evolution of characters in phylogenetic analyses. Characters such as secondary venation pattern, types of stomata, presence of hypodermis, trichome morphology, and type and location of mucilaginous idioblasts are relevant at the specific level. Secretory structures such as secretory base trichomes, mucilaginous idioblasts, and phenolic idioblasts are found in the leaflets of representatives of the genus. We reinforce the monophyletism of the Lineata clade, with craspedodromous pattern as a possible synapomorphy. Our data indicate new characters useful for the taxonomy of the genus, possible synapomorphies, and support future studies on the systematics of Machaerium.