Phylogenetics and Evolution of Epacrids: a Molecular Analysis Using the Plastid Gene rbcL with a Reappraisal of the Position of Lebetanthus

Abstract

An expanded rbcL sequence dataset has been assembled forall capsular-fruited genera and a majority of fleshy-fruited genera inEpacridaceae sensu Powell et al.(1996), including a new accession of the South American monotypicLebetanthus Endl. Parsimony and maximum likelihoodanalyses strongly support an epacrid clade which includes bothLebetanthus and Prionotes R.Br.These two taxa are robustly grouped and placed sister to the rest of thefamily. Most of the remaining epacrids fall into several well-supportedgroups, some of which correspond to previously recognised infrafamilial taxa:the Cosmelia, Epacris,Richea and Styphelia groups.Needhamiella L.Watson andOligarrhena R.Br. form a clade that is distant from theStyphelia group, to which they have traditionally beenallied on the basis of their fleshy fruit and uniovulate locules.Archeria Hook.f., a small genus found in New Zealand andTasmania, is distant from all of these well-supported groups, including itstraditional ally, the Epacris group. Several novelgeneric relationships are evident on the rbcL tree.Epacris Cav. is paraphyletic; one of the includedspecies clusters robustly with Budawangia Telford andRupicola Maiden & E.Betche. Strong evidence is alsoadvanced for the position of Pentachondra R.Br. assister to the remainder of the Styphelia group. Beyondthis, however, relationships within the Styphelia groupare poorly supported. On the basis of these results, a new taxonomy of theepacrids, comprising seven tribes, is proposed. Six of these correspond topreviously recognised taxa; one new tribe, Archerieae, is recognised. A key tothe tribes is provided. Character evolution within the family is discussed andreinterpreted in the light of the rbcL tree.