Leaflet anatomy of the Dipterygeae clade (Faboideae: Fabaceae): evolutionary implications and systematics.

Dipterygeae traditionally comprised the genera Dipteryx (12 species), Pterodon (three species) and Taralea (seven species), but Monopteryx (three species; originally in tribe Sophoreae) emerged in recent molecular phylogenetic studies as sister to the clade comprising Dipteryx, Pterodon and Taralea. This study aimed to evaluate anatomical vegetative characters of leaflets in Dipterygeae to highlight (1) new synapomorphies for the clade, (2) characters supporting intergeneric relationships currently resolved by molecular data, (3) diagnostic characters for the taxonomy at the genus and species levels and (4) information about the morphology and histochemistry of secretory structures. Leaflets were studied using light and scanning electron microscopy. The presence of idioblasts in the main vein, loss of elongate secretory cavities and curved leaflet margin are shared features of Dipterygeae. Furthermore, leaflet anatomy in all genera investigated is taxonomically useful at both genus and species levels. Secretory cavities, idioblasts and glandular trichomes are reported, confirming Dipterygeae as a secretory clade. Lipids and phenols are present in spherical secretory cavities and in idioblasts, respectively. The dataset supported the relationships as currently resolved by molecular studies. Indeed, our data indicate that the leaflet anatomy of Monopteryx supports its inclusion in the Dipterygeae clade. [ABSTRACT FROM AUTHOR]