Phylogenetic relationships of Rhododendron section Azaleastrum (Ericaceae) based on ITS sequences

The subgenus Azaleastrum Planch. of Rhododendron L. (Ericaceae) was traditionally divided into two sections, i. e. sect. Azaleastrum ( Planch.) Maxim. and sect. Choniastrum Planch. The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA from seven species and one variety of subg. Azaleastrum were sequenced. The ITS sequences of these taxa, together with those of two species of sect. Choniastrum and two related monotypic subgenera, subg. Mumeazalea Maxim. and subg. Candidastrum (Sleumer) Philip. & Philip., were analyzed to reconstruct the phylogeny of the sect. Azaleastrum using PAUP4.0b8, with R. redowskianum Maxim. of subg. Therorhodion (Maxim.) Gray as outgroup. Six most parsimonious trees with a length = 60, a CI = 0.917, and an RI = 0.898 were obtained by the maximum parsimony analysis when the gaps were treated as missing. The topology of the strict consensus tree was identical with that of the maximum likelihood analysis with slightly different bootstrap values. Subg. Candidastrum was nested in the basal position. Subg. Azaleastrum was not monophyletic, but both sect. Azaleastrum and sect. Choniastrum were monophyletic groups with bootstrap values of 81% and 100% respectively. Sect. Azaleastrum was divided into two clades with bootstrap values of 93% and 62% respectively. Subg. Mumeazalea was resolved as sister to sect. Azaleastrum.