Large indels obscure phylogeny in analysis of chloroplast DNA (trnL-F) sequence data: Pomaderreae (Rhamnaceae) revisited

Abstract

Phylogenetic analysis of 69 ingroup-taxa of Pomaderreae using trnL-F sequences confirm the monophyly of the tribe. The analysis was impeded by a paucity of informative characters and the presence of apparently homoplasious indel characters and base changes within the P8 region of the trnL intron: the strict consensus tree of the trnL-F analysis is less resolved and had fewer supported clades than in a previous ITS analysis (Kellermann et al. 2005). The backbone of the cladogram is not supported and relationships between genera/clades are somewhat uncertain. The genera Cryptandra, Stenanthemum and Polianthion are well supported. Pomaderris groups with Siegfriedia and Trymalium, but only individual clades within these genera receive support. Blackallia biloba is related to two atypical species of Stenanthemum and B. connata to Cryptandra, but this grouping depends on the exclusion of homoplasious indel characters. Species of Spyridium only group in one clade when these indels are excluded, otherwise they are located in a polytomy at the base of the cladogram. The results mostly agree with earlier findings using ITS sequence data. Two new genera containing atypical species of Stenanthemum are suggested. A synopsis of the Australian genera of Rhamnaceae is provided.