Can leaf morphology and anatomy contribute to species delimitation? A case in the Campomanesia xanthocarpa complex (Myrtaceae)

Campomanesia Ruiz & Pavon is a South American genus with species delimitation problems similar to those of other genera of the Myrtaceae. We studied the C. xanthocarpa complex to evaluate the morphological and anatomical characters of the leaves and their potential use to the taxonomy of the group. We analyzed 13 morphotypes corresponding to three species of this complex (C. adamantium, C. eugenioides, and C. xanthocarpa) and three related to it (C. cavalcantina, C. costata, and C. rhombea) using light and scanning electron microscopy. Differences in the bases and margins of the leaf blades, domatia, and cuticular ornamentations on the abaxial surface of the leaf supported the recognition of nine taxa. The presence of fibers surrounding the vascular bundles of the leaf blade and the types of vascular arch endings characterize two groups supported by lineages previously recovered after phylogenetic studies. Leaf morphology and anatomy proved to be useful to better delimitations within the C. xanthocarpa complex, including the reestablishment of C. caerulea, C. littoralis, and C. repanda (species related to C. adamantium, C. xanthocarpa, and C. eugenioides, respectively).