A molecular phylogeny and a revised classification of Ornithogaloideae (Hyacinthaceae) based on an analysis of four plastid DNA regions

Abstract

AbstractThe most recent classification of Hyacinthaceae subsumes all members of Ornithogaloideae into the single large genus Ornithogalum comprising 250–300 spp. A combined molecular phylogenetic analysis of matK, trnL intron, trnL‐F spacer and rbcL plastid DNA sequence data was carried out to assess possible alternative treatments. The study includes 70 taxa, representing all segregate genera that have been recognised in the subfamily and over 20% of the species. The resulting phylogeny identifies three, well‐supported primary clades. Clade A comprises a grade constituting the majority of species of Stellarioides plus the Madagascan Igidia, in which is nested a strongly supported clade comprising Albuca and Coilonox; Clade B comprises Dipcadi sister to Pseudogaltonia; and Clade C comprises Eliokarmos, Cathissa, Galtonia, Honorius, Loncomelos, Melomphis, Neopatersonia, Ornithogalum, Zahariadia and two species of Stellarioides. The Madagascan Avonsera convallarioides is weakly supported as sister to the rest of clade C. Several of the segregate genera of Ornithogalum are shown not to be monophyletic although many of the lineages identified by the analysis correspond to lower level taxa that have been recognised in the group. Each of the three primary clades has morphological integrity and could be recognised taxonomically, either at the level of tribe or genus. Within these clades, however, many lineages are poorly defined morphologically and thus their recognition at the level of genus is problematical. Alternative taxonomic treatments are assessed but considerations of nomenclatural stability and taxonomic utility predicate that these lineages are best recognised at infrageneric level. We accordingly prefer to define the genera more broadly. Clade A is recognised as genus Albuca, clade B as comprising the genera Dipcadi and Pseudogaltonia, and clade C as the genus Ornithogalum. Monophyletic, morphologically diagnosable lineages within the genera Albuca and Ornithogalum are treated as subgenera and sections. A revised classification is presented, with necessary new combinations and complete listings of all currently accepted sub‐Saharan species.