Boronia

Duretto, Marco F., Heslewood, Margaret M. & Bayly, Michael J., 2023, A molecular phylogeny of Boronia (Rutaceae): placement of enigmatic taxa and a revised infrageneric classification, Australian Systematic Botany 36 (2), pp. 81-106 : 100-101

Relationships between the sections of Boronia and phylogenetic diversity

The resolution of relationships between the 10 sections of Boronia is not conclusive, apart from the close relationship of section Alatae with section Corynophyllae , and that of section Imbricatae with section Pedunculatae in all analyses ( Fig. 1, S1 , S 2). In the combined maximum-parsimony analysis, these two clades formed a polytomy with the remaining six sections. The Bayesian analysis contained more structure with sections resolving into two well-supported clades. The first contains sections Boronia and Ovatae sister with robust support (1.00 PP) and these sister to Boronella (1.00 PP). The second clade contains the remaining seven sections with little internal support except for the strongly supported Imbricatae + Pedunculatae and Alatae + Corynophyllae clades and the latter sister to section Inornatae with good support (0.98 PP).

Of the 10 sections recognised here, 6 contain 3 or fewer species. The three monotypic sections, Alatae , Corynophyllae and Imbricatae , along with section Ovatae (3 spp.), are confined to south-western Australia. Two sections contain two species, namely, Algidae sens. strict. from south-eastern Australia, and Inornatae from south-western Australia and South Australia. Sections Boronia (43 spp.) and Pedunculatae (11 spp.) are both found in south-eastern Australia (including Tas.) and south-western Australia. The largest section, Valvatae (66 spp.), is found in south-western Australia, eastern Australia (being absent from SA and Tas.) and northwestern Australia, and is the only section found in tropical

Australia. The final section, Boronella (4 or 5 spp.), is confined to New Caledonia.

South-western Australia contains significant phylogenetic diversity with 8 of the 10 sections present, 4 of which are endemic to the region. The two Australian sections with infrasectional classifications demonstrate contrasting patterns, with the phylogenetic diversity of section Boronia being higher in south-western Australia, whereas that for section Valvatae is higher in eastern and northern Australia.

Figures

Fig. 1. Bayesian 50% majority-rule consensus tree from the combined analysis of two nuclear (ITS, ETS) and three plastid markers (psbA–trnH, trnL–trnF and rbcL), with thick lines showing supported clades (≥0.95 PP). Jackknife percentages from MP analysis are indicated with symbols above branches: 100% JK (closed triangle); 90–99% JK (closed circle); 75–89% JK (open triangle); 50–74% JK (open circle). New or revised sectional assignments are indicated in bold. Section Boronia clade has been collapsed and is shown in detail in Fig. 2.