A phylogenetic evaluation of Leandra (Miconieae, Melastomataceae): a polyphyletic genus where the seeds tell the story, not the petals

Abstract

Melastomataceae is a tropical family of 4500–5000 species divided into nine tribes. The largest tribe, Miconieae, is composed of approximately 2200 species in 30 genera and is found exclusively in the Neotropics. Previous phylogenetic analyses of the Miconieae have suggested that many of the genera are derived from a paraphyletic Miconia. However, these analyses only included six species of the large genus Leandra, so its phylogenetic affinities remained unclear. As currently defined Leandra is characterized by acute petals and terminal inflorescences, but some species of Miconia, Clidemia and Ossaea also have these characters. In this study, we present an analysis of nrITS sequence data for a sample of 63 species of Leandra. The genus is clearly resolved as polyphyletic, but some distinct and well‐supported clades exist. Some of these partially correspond to sections recognized in the nineteenth century by Cogniaux, or to geographic distribution. The distribution of seed structure characters is better correlated with the phylogeny than traditional characters, such as petal morphology. Seed appendages in Leandra have evolved independently at least four times. © The Willi Hennig Society 2007.

Taxonomic notes on Leandra (Melastomataceae, Miconieae)

“…The position of the inflorescence was considered diagnostic for these sections (terminal in Oxymeris and transitioning from terminal to lateral in Chaetodon), but this character is highly variable among some species and not always evident on herbarium sheets lacking either flowering or fruiting material. Phylogenetic analyses showed that these sections are not monophyletic as previously discussed (Martin et al 2008), confirming that this character is homoplastic. The types of L. nutans and L. urophylla share with L. acutiflora sparse, deciduous, minute dendritic trichomes, and leaves distinctly plinerved bearing white tufted domatia on the axils of the lateral nerves on the abaxial surface.…”

“…Inflorescence position is one of the two characters traditionally used to circumscribe genera in the tribe Miconieae and great taxonomic importance has historically been placed on this character. Nonetheless, it has been demonstrated to be either prone to miscoding (Judd & Skean 1991) or to be highly homoplastic (Michelangeli et al 2004, Martin et al 2008.…”

“…and Secundiflorae Cogn., while the third clade is mostly composed of species from the five remaining sections, the genus Pleiochiton A.Gray, and some species of Ossaea DC. and Clidemia D.Don (Martin et al 2008). This last clade (Leandra sensu stricto, following Goldenberg et al 2008) includes ca.…”

Two new species of <I>Leandra</I> s. str. (<I>Melastomataceae</I>) from the Atlantic Forest in Espírito Santo, Brazil

“…While the whole genus seems to be polyphyletic, most of the species fall into three distinct clades. One of them (Leandra 'sensu stricto') includes almost all species of the genus occurring in eastern Brazil, plus some species previously described in the genera Ossaea DC., Clidemia D.Don, and all Pleiochiton A.Gray, also from eastern Brazil (Michelangeli et al 2004, Martin et al 2008. The species in this group have shrubby habit, non-scorpioid inflorescences, narrow petals and unappendaged seeds.…”

“…Leandra Raddi is a genus with c. 250 species, all restricted to the Neotropics (Martin et al 2008). While the whole genus seems to be polyphyletic, most of the species fall into three distinct clades.…”