Molecular phylogeny of the genus Philodendron (Araceae): delimitation and infrageneric classification

Abstract

The genus Philodendron (Araceae) is a large neotropical group whose classification remains unclear. Previous classifications are based on morphological characters, mainly from the inflorescence, flower and leaf shape. The classification by Krause, with few modifications, is still the most commonly used system. To examine phylogenetic relationships in the genus, two ribosomal DNA nuclear markers, internal transcribed spacer (ITS) and external transcribed spacer (ETS), and the chloroplast intron rpl16, were sequenced and analysed for more than 80 species of Philodendron and its close relative Homalomena. According to the resulting phylogeny, the genus Homalomena may be paraphyletic to the genus Philodendron. The inclusion of the American Homalomena species within the genus Philodendron might resolve this taxonomic problem. All three subgenera of Philodendron were revealed as monophyletic. Below the subgeneric level, the groups obtained in our phylogeny globally correspond to sections recognized in previous classifications. Among the morphological characters used by previous taxonomists to build their classifications, and which we optimized onto one of the most parsimonious trees, most characters were found to be homoplasious. However, leaf shape, characteristics of the sterile zone on the spadix and venation patterns are useful for delimiting subgenera and sections within the genus.

A new species of <i>Philodendron</i> (Araceae) and a key to Brazilian Atlantic Forest species of <i>P.</i> subgenus <i>Pteromischum</i>

“…in Krause 1913), can be morphologically characterized by the well-developed foliar sheath and anisophyllous sympodial growth, bearing many leaves per article (Grayum 1996). Mayo (1989), based on anatomical investigations, elevated Pteromischum to the status of subgenus, a decision that was later supported by a molecular phylogenetic study (Gauthier et al 2008), which indicated that the other two subgenera were also monophyletic.…”

A bibliographic review on the family Araceae with foccus on the generaPistia, Philodendron and Montrichardia: botanical, phytochemical and biological activity aspects

“…A sua elevação a subgênero se apoiou em estudos anatômicos (Mayo, 1989) e filogenéticos (Gauthier, Barabé e Bruneau, 2008). Este subgênero ocorre na América Central e na Amazônia Ocidental (Grayum, 1996).…”

Flora of Guaramacal (Venezuela): Monocotyledons

“…The three subgenera of Philodendron (see generic description above) originally recognized on morphological criteria alone are supported as monophyletic by molecular data (Gauthier et al, 2008). However, this classification could change with resolution of the larger problem concerning generic boundaries.…”

“…The relationship between Philodendron and Homalomena Schott, a genus found in tropical America and Asia, is unresolved (Cabrera et al, 2008;Gauthier et al, 2008). Nonetheless, these two genera and several smaller ones form a strongly supported clade (Philodendron clade) that is united synapomorphically by a pistillate-sterile-staminate pattern of spadix floral zonation (Cusimano et al, 2011).…”