Phylogenetic analysis of the Sonneratiaceae and its relationship to Lythraceae based on ITS sequences of nrDNA

Phylogenetic analyses were conducted using seven species in two genera of S onneratiaceae, seven species in five genera of the related Lythraceae and 2 outgroups based on DNA sequences of the internal transcribed spacer (ITS) and the 5.8S coding region of the nuclear ribosomal DNA to determine the pr oper systematic placement of the Sonneratiaceae. Paraphyly of the tradition al Lythraceae was shown with the genus Lagerstroemia nested within the Sonn eratiaceae. The Sonneratiaceae occurred within the Lythraceae with high boo tstrap value support(96%). The two traditional genera constituting Sonnerat iaceae were in different well-supported clades. Duabanga (Sonneratiaceae) i s sister to the clade of Lagerstroemia (Lythraceae) (82%). The mangrove gen us Sonneratia (100%)formed the other monophyletic group. It was located ter minally within the Lythraceae clade and comprised two clades: one consistin g of S. apetala, S. alba, S. ovata, and S. hainanensis; the other including S. caseolaris and S. paracaseolaris. The results indicated that species pr eviously placed in two different sections (Sect. Sonneratia and Sect. Pseud osonneratia) of Sonneratia occurred within the same clade, and the taxonomi c classification was not supported by the molecular analysis of the TTS reg ion sequences. Based on the phylogenetic analyses of the TTS regions, the S onneratiaceae were shown to be nested within the family Lythraceae. Therefo re, the sequence data presented here do not support the recognition of the Sonneratiaceae as a distinct family, but instead support the inclusion of S onneratiaceae in the Lythraceae proposed by other authors.