“…They are distinguished from other Bursera by their reddish peeling phellem (outer bark), compound leaves without wings on the rachis, ovate to broadly elliptic entire leaflets with mostly acuminate apices and brochidodromous venation, and three-valved fruits with reddish pseudarils covering the endocarp completely. Although the complex has long been recognized as distinct (McVaugh and Rzedowski, 1965;Rzedowski and Kruse, 1979), and is well supported in molecular phylogenies (Becerra, 2003;Becerra and Venable, 1999), species limits and relationships within the group have always been regarded as problematic (Daly, 1993;Rzedowski et al, 2005Rzedowski et al, , 2007. Molecular phylogenies have included only a few species of the complex and provide little resolution within the group (Becerra, 2003;Becerra and Venable, 1999).…”